Tropical Fruit Forum - International Tropical Fruit Growers

Citrus => Cold Hardy Citrus => Topic started by: kumin on January 25, 2019, 08:04:22 AM

Title: F2 citrange winter hardiness trial
Post by: kumin on January 25, 2019, 08:04:22 AM
I'm trialing a population of F2 Citrange seedlings this winter in zone 6b in SE PA. There is considerable variability in the resistance to low temperatures, with some dying in November and others still viable at this point. The population is a mixture of nucellar  F1 and zygotic F2 seedlings. The F1 are freezing out at present, but a number of the F2 are surpassing the F1 in hardiness and a few appear to be surviving the winter. My hope is that several will approach the hardiness of P. trifoliata.

Any survivors would then be evaluated for palatability. My focus is centered on hardiness, with palatability being secondary.

I've grown poncirus since 1980 and lost everything above the snowdrifts in Jan of 1994. This was after 2 consecutive nights at -24 F. The trees resprouted below the snow height and haven't been injured since.
Title: Re: F2 citrange winter hardiness trial
Post by: hardyvermont on January 25, 2019, 01:10:14 PM

I've grown poncirus since 1980 and lost everything above the snowdrifts in Jan of 1994. This was after 2 consecutive nights at -24 F. The trees resprouted below the snow height and haven't been injured since.

kumin, Thanks for this information.  Where are you growing poncirus?  Full sun, partial shade, protected from the wind?  Have you noticed any difference between poncirus plants? 
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 25, 2019, 01:42:38 PM
hardyvermont, I have Poncirus plantings at three locations on the same property. All are in clay soil, one location  is well drained , the remaining two are poorly drained. The trees growing in full sun have the the most vigor. Last winter I removed a M. Grandiflora tree that was shading the largest Poncirus tree and upon release the Poncirus  tree responded positively. Most of my trees are fairly close to buildings which could block or concentrate the wind. I haven't recently germinated  Poncirus seedlings on large scale. When I did in the past, I saw the occasional seedling I suspected of being tetraploid. Due to generally having rather high % of nucellar (clonal copies) seedlings, one usually sees a lot of uniformity.

The citranges by contrast have no wind protection other than the density at which they're planted. They are planted at about 20 seedlings per sq. ft.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 25, 2019, 01:58:21 PM
hardyvermont, I lost a planting of first year Poncirus a few decades ago by planting them into loosely cultivated soil and not allowing the soil to solidify during the growing season. During the winter 500-600 succumbed to late winter frost heave. In early April I could very easily pull the dead trees out by hand. They were approximately a foot tall at that time. There were no survivors. Mulching the soil might have saved them all.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on January 25, 2019, 03:04:53 PM
What  is your source of citrange seeds?
I'm glad to know someone else in the USA is growing F2 citrus x trifoliate hybrids. But mine are still at the tiny seedling stage, certainly not ready to face zone 6 winter.  In fact,  I assume I'll need at least one backcross to trifoliate, maybe two.  I would love it if you proved me wrong.
Keep us up to date on your results
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 25, 2019, 07:53:36 PM
Walt, being of similar age as you, I am using brute force (large populations) in an attempt to increase the odds of obtaining very hardy F2 segentranges in a short time span. After planting a number of putative " cold hardy " cultivars that failed, I am seeking plants with nearly the full hardiness of Poncirus.  I began with an initial population of 20,000+ seedlings. The seedlings are 85% nucellar and 15% zygotic, so the effective population under trial  is 3,000 plants.

The seeds were germinated in April of 2018 and planted outdoors in June, 2018. These plants are not protected against the cold in any way. Survivors, if any, will be protected going forward, knowing they have the necessary genetics. At this point the population will be very small and easier to protect.

Googling  "citrus tree seed California" will give you 2 hits that sell seed by liter or quart. If you need details on how to germinate large quantities of Citrus seed I can't make a recommendation, but I can tell you how I did mine.
(https://i.postimg.cc/LqvM71Vm/IMG-20180508-133913-1.jpg) (https://postimg.cc/LqvM71Vm)

(https://i.postimg.cc/hhXqyhQq/IMG-20180602-064120-1.jpg) (https://postimg.cc/hhXqyhQq)

(https://i.postimg.cc/sQ8bd9GC/IMG-20181224-112926.jpg) (https://postimg.cc/sQ8bd9GC)
Title: Re: F2 citrange winter hardiness trial
Post by: Florian on January 26, 2019, 04:45:45 AM
Check out the Hamlin x FD: http://tropicalfruitforum.com/index.php?topic=28270.msg321750#msg321750. (http://tropicalfruitforum.com/index.php?topic=28270.msg321750#msg321750.)
It appears to be rather coldhardy.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on January 26, 2019, 02:33:55 PM
Kumin
3,000 is a number I can respect.  I stated in long term cold hardy thread why I think F2 citranges will be less cold hardy than than F1.  But 3,000 trys?  If I'm wrong about even one of them, you win.  This is a real effort.
I think your chances would be better with older trees.  But you are doing a big job, so do it your way and I hope you succeed.
Thanks for the information about seed source.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on January 26, 2019, 02:48:24 PM
HamlinxFD is certainly not hardy in zone 6.

I wonder if citrandarins like US852 are  better choice for such large scale testings. I guess 5-10 mother plants will give sufficient quantities of starting seeds.

For the germination, from my experience, the best method is perlite/buggy approach used for palm seeds.
Seeds are germinated in zip locked plastic bag in moist, but not wet perlite at 25C. After germination seedlings can be transplanted in common pots to grow under artificial light and transplanted in  spring in the open ground.
I am germinating each season around thousand of seeds  by this method (my record is 3000), selection to discard nucellar seedlings  and plants with poncirus aftertaste in leaves can be done very early, before open ground planting.
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on January 26, 2019, 02:56:35 PM
I wonder if citrandarins like US852 are  better choice for such large scale testings. I guess 5-10 mother plants will give sufficient quantities of starting seeds.
I just looked at my germinating US852 seeds. Four of them had begun sprouting, and of those 2 of them were polyembryonic and 2 only had single sprouts.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 26, 2019, 02:59:03 PM
3,000 is a little less impressive than it sounds, approximately half are genetically dwarf which is not unusual for F2 zygotic citranges. Many of them are too lacking in vigor to hold much promise. Long story short- I did a status survey today and believe 100 to 150 plants are relatively unscathed, but February can be brutal to plants. Some winter cold damage is accumulative, as any individual cold event can be. The best looking plants phenotypically favor Poncirus rather strongly. However, they are not identical to one another in appearance. Hopefully they will carry some Citrus genes.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 26, 2019, 04:32:51 PM
The germination technique I used, was placing the seeds in mesh bags, then using a repurposed dishwasher with thermostatic control of water temperature, aerated/soaked them for 24 hours at 86 degrees F. I then removed them and scarified the seed coat for 30 minutes, followed by neutralizing the solution and rinsing them thoroughly. They were then returned to another 24 hrs of soaking, followed by planting immediately into a germination bed, again at 86 degrees F. They were planted 1.8 - 2 millimeters deep. Areas cooler than 86 degrees had a bit of seed decay. Seeds planted too shallow lifted out of the soil. Seeds planted too deep had delayed emergence. Emergence began at 7 days and continued a little over a week.

 The seed soaking procedure was used, as the seed was stored, dry seed. This would be unnecessary with fresh seed. Soaking the seed helps to synchronize the germination and subsequent emergence of seedlings.

The water used in the soak was slightly chlorinated to prevent decay. The water was drained and replaced every 6 hours. As the seedlings grew larger and May weather became warmer the bed temperature was dropped to 75 deg. F. The seedlings were field planted on June 12, 2018. By end of September the tallest seedlings were 48" tall. The average was closer to 30" - 36 " tall.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 26, 2019, 06:42:50 PM
Ilya 11 Thanks for your suggestion of a leaf taste test. During field planting I noticed some plants were pleasantly sweetly aromatic, but I didn't trust that there was a definitive correlation between plant sap taste and fruit taste. Relying on such a test could dramatically reduce the time, labor, space, etc. required to plant seedlings.
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on January 27, 2019, 01:18:28 AM
I wonder if citrandarins like US852 are  better choice for such large scale testings. I guess 5-10 mother plants will give sufficient quantities of starting seeds.
Yes, US 852 is a hybrid between Changsha mandarin (already pretty hardy) and trifoliate, and can survive well into zone 7.

Apparently their flavor isn't too terrible. There's a video where one guy is managing to enjoy eating them.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on January 27, 2019, 01:35:39 AM
I've been away from my computer a few hours, but this hasn't been out of my mind.  Kumin. your results so far alreadyshow  that I was wrong that all the F2 would be less hardy than the F1.  You said ALL your F1s are dead, but some of your F2s live.  I really didn't expect that.
You made my day.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 27, 2019, 03:26:06 AM
Photos taken yesterday of one plant lacking hardiness and one showing little damage.

(https://i.postimg.cc/HVQRjd07/IMG-20190126-123936.jpg) (https://postimg.cc/HVQRjd07)

(https://i.postimg.cc/kRSZQdkz/IMG-20190126-124019.jpg) (https://postimg.cc/kRSZQdkz)


Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on January 27, 2019, 03:54:43 AM
I then removed them and stratified the seed coat for 30 minutes, followed by neutralizing the solution and rinsing them thoroughly.
Kumin,
I do not understand what do you mean by stratification? Certainly not cold treatment, may be washing soda incubation?
Your brute force approach is very impressive, hopefully it will produce some hybrids as resistant as poncirus. Still, most of the freeze damage occurs in spring when small stem cracks begin to be infected.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 27, 2019, 04:56:13 AM
Ilya11, Yes, it was a strictly controlled alkali treatment followed by water flushing, again followed by weak acid rinse. then flushed repeatedly. At this point the final 24 hour soak was begun. I've just noticed I referred to the process as "stratification" my intent was to say "scarification".
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on January 27, 2019, 05:19:14 AM
kumin, you are doing impressive work!
Just a notification there is a Citrandarin F2 (but it could be F3 too) in Germany fully hardy and very similiar to Poncirus but not zone 6 more like zone 7.
It is a HRS 899 (or offspring of it) but unknown which one. There are (or were) HRS 899 a to k . All HRS 899 are offspring of US852 or another hybrid with Changsha x Poncirus parentage.
(https://farm8.staticflickr.com/7819/39926758763_9fe2644d06_z.jpg) (https://flic.kr/p/23Qc5mt)

on the left HRS 899 to the right Poncirus

 (https://flic.kr/p/23Qc5mt)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 27, 2019, 05:38:31 AM
Thanks, Mikkel the reversal of the hybrid retaining the fruit while dropping the leaves is interesting. One aspect of Poncirus fruit is the rapid dropping of the fruit followed by short storage life. I have no experience with the variability of Poncirus hybrids fruit storage life.
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on January 27, 2019, 02:42:50 PM
@Mikkel I can confirm your observation. Fruits of HRS89 (Poncirus x Changsa F2) stay much longer on the tree than the fruits of Poncirus trifoliata. See also my other post with photo here: http://tropicalfruitforum.com/index.php?topic=30863.0 (http://tropicalfruitforum.com/index.php?topic=30863.0)
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on January 27, 2019, 06:02:12 PM
@usirius
I have the feeling this picture might be yours? Is it?
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on January 28, 2019, 03:16:15 AM
Yes mikkel, the picture above including the text has been done by myself some years ago ;-)
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on January 28, 2019, 05:43:43 AM
I knew it :) We had some contact then.
Shall I put your name under the picture?
Is this 899 above the same as the pear shaped one you posted in the other thread?
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on January 28, 2019, 05:59:04 AM
Concerning the picture all is okay! On the first view I think it is the same HRA 899 selection. If helpful can check this in my garden to a later time. -  But which selection is it? The foliage is mostly trifoliate. Thank you also for the hint to find the description of Bernhard Voss- I catched the direct link to this descritption: https://web.archive.org/web/20130106094639fw_/http://www.agrumi-voss.de/hrs.htm (https://web.archive.org/web/20130106094639fw_/http://www.agrumi-voss.de/hrs.htm)    ->   This description is very old and it is related to the habitus of relatively young plants. It is possible that shape and size of foliage varies during aging. So a more actual description including fruits would be very interesting. Do you know if Bernhard Voss has done any newer documentation of the HRS899 selections - may be he published a book about those or has written something about them in an article in a garden journal?
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on January 28, 2019, 06:30:57 AM
I spoke several times with him. As far as I know he has no plants left. Some years ago he gave most of his plants away. I picked what seemed to be interesting but there were only 899 J and A among the plants.
Meeder, Eugen Schleipfner and CitrusBali might have some other varieties. But it seems many have lost the letter so it is often only HRS 899.

Yes I think the mature plants might have different leaves now. In his description only O and Q are fully trifoliate .
Here  (https://web.archive.org/web/20110906153931fw_/http://www.agrumi-voss.de/frosttab.htm) you can find some results from the cold tests.

How many HRS 899 do you have?
Could you check your plant again I am very interested.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 28, 2019, 08:08:51 AM
Mikkel, thanks for the winter hardiness information. It's apparent there's a great deal of variation between individual cultivars.
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on January 28, 2019, 02:05:28 PM
@ Mikkel: I started with about 8 selections of HRS899. Only the selections survived after the first winter. Another selection died next winter, and for many years I had only two selections left. I'm not sure, maybe three or four years ago one of the two remaining selections died. After all these years only this one has survived and this selection is as robust in my opinion as Poncirus trifoliata. It showed no damage in all winters in the past. Even an early warm-up in the spring with subsequent freezing is no problem for this selection. This is often a big problem for most "robust" citrus hybrids and selection. The only negative feature is that the fruits are inedible - smaller and a worse taste like poncirus fruits ;-)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on January 29, 2019, 09:46:09 AM
Kumin,
I wonder if you observed the seedlings with  tendency of autumn leaf yellowing/falling ?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 29, 2019, 11:59:46 AM
Ilya11, There is considerable variation in leaf color, some are very dark green, some are showing a bronzing response to the cold. Others show a reddish tint where the leaflets join the petioles. The F1 seedlings are uniformly dark green and shriveling as they desiccate. There are a number that have a yellowish cast, but most leaves have not dropped at this point.

One thing to keep in mind is that straight Poncirus often isn't reliably deciduous until the third year. I'm attaching a photo of self seeded 2-year old pure Poncirus that have changed color somewhat, but still haven't dropped their leaves.

(https://i.postimg.cc/XXNxW2x5/IMG-20190128-120620.jpg) (https://postimg.cc/XXNxW2x5)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on January 29, 2019, 12:06:52 PM
Thank you, I am quite convinced that for the robust hardiness beyond zone7, the citrus hybrid should drop its leaves in autumn. Among my F1xcitrus seedlings such plants are extremely rare.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on January 29, 2019, 12:40:52 PM
Ilya11, I agree with you. It's very likely that being evergreen puts too much stress and demands on the plants. There are a few plants that have dropped their leaves. I am not certain if this is from stress or preparation for winter. The trees I favor at present may not be the best in the next several months.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 01, 2019, 01:45:57 PM
The present low temperature event has struck the local area. Recent daytime highs are approximately +15 deg. F., today is expected to reach +20 F. Local lows have been +3 F,   -11.8 F, +2 F and tonight + 10 F. The - 11.8 F reading was considerably lower than the forecast. These midwinter temperatures aren't a problem for Poncirus. Concerning the F2 citranges, however, this is a severe test. I will survey the plants again once we get a prolonged thaw .  Survival is obviously not assured. A thaw is forecast to begin tomorrow. If any manage to survive they will be protected in subsequent winters.

(https://i.postimg.cc/w3v69CCs/IMG-20190131-071746.jpg) (https://postimg.cc/w3v69CCs)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on February 01, 2019, 06:26:06 PM
At least  all your C35 nucellar seedlings will be dead, C35 is probably the least hardy of all citranges.
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on February 02, 2019, 12:24:02 AM
Citranges are not as hardy as citrandarins or citrumelos because oranges are not as hardy as mandarins or the vigorous grapefruit varieties that citrumelos were bred from. (Though I don't think the difference is huge)

However, I predict we'll see a lot more hardiness manifest in the F2 generation, at least in 25 percent of the seedlings.
That's because another cross has the chance to eleminate dominant genes that may carry cold vulnerability, or manifest recessive genes that would carry cold hardiness.
When you have an F1 cross, you're pretty much guranteed that 50 percent of the genes are going to come from poncirus and 50 percent from orange, but when you take that hybrid and cross it again, even if it's with itself, there are a lot more possibilities.
You might (though exceedingly unlikely) even be able to manifest all the good genes from the edible orange parent with all the beneficial cold hardiness genes from the poncirus parent.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on February 02, 2019, 05:18:54 AM
Poncirus contains several gene regions responsible for its freeze resistance and its genome is highly heterozygous. That is why  F1 hybrids with citrus are showing a large variation for winter hardiness.
Three hundreds of its F1 hybrids with very frost sensitive pummelo show a wide distribution of freeze damage.

 article (http://journal.ashspublications.org/content/128/4/508.full.pdf)

(https://b.radikal.ru/b13/1902/bb/5a2a6f76c8cf.jpg) (https://radikal.ru)

Quite possible that C35 citrange inherited a rather unfavorable set of gene alleles from its poncirus parent explaining its poor winter performance.
Title: Re: F2 citrange winter hardiness trial
Post by: Millet on February 02, 2019, 02:06:25 PM
For forum members reading through this post, that are not familiar with what the variety HRS 899 is see below:

Newly bred variety, the tests havent been finalized yet. It is a cross of tangerine variety 'Changsha' and Poncirus. It grows well and fast, has only simple leaves and is significantly hardier than the citranges 'Rusk' and 'Morton'. Its flowers are small, comparable to those of tangerines. B. Voss says about 15 clones labeled HRS and a capital letter, of which the clone 'HRS-899 J' is supposedly hardy to -15C and the clone 'US 899 F' has much more vigorous growth. Its leaves mono-, di- and trifoliate and its a little bit hardier.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 03, 2019, 03:30:55 PM
Today's high temperature is 45deg. F. I've taken a few photos to see how the best plants have fared. Most look similar, but a little worse for wear and tear. The best ones look to be in similar condition to my Poncirus of similar size. These may have a chance at survival.

This is after almost a week of temperatures below freezing, the lows ranged from +3 deg. F. to -11.8 deg F., there were several days of high temperature +/-  +15 deg F. I am pleased with the results thus far, but percentages of plants looking this good are low.
Of special interest to me is plant # 3 having a mixture of unifoliate and trifoliate leaves.


(https://i.postimg.cc/yDD5Z7BM/IMG-20190203-145004-1.jpg) (https://postimg.cc/yDD5Z7BM)

(https://i.postimg.cc/yW7bTmsX/IMG-20190203-144804-3.jpg) (https://postimg.cc/yW7bTmsX)

(https://i.postimg.cc/BXXNhNyD/IMG-20190203-144536-1.jpg) (https://postimg.cc/BXXNhNyD)

(https://i.postimg.cc/V5HWbn6N/IMG-20190203-144403.jpg) (https://postimg.cc/V5HWbn6N)
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on February 03, 2019, 05:47:57 PM
This is after almost a week of temperatures below freezing, the lows ranged from +3 deg. F. to -11.8 deg F.,
It's surprising that anything that's not pure poncirus could survive -10 F.
I'd view this as a success.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 03, 2019, 05:58:59 PM
At this point I'm debating protecting a few of the most promising specimens for the rest of the winter, in order to preserve their genetics. It would be a deviation from my original plan, but I already have $2,000.0 in this project and it might be prudent.

Although I can be certain that the seed parent is F1 C-35 citrange, there is no definitive proof that the pollen parent is the same. Depending on blooming time and seed grove layout, the pollen parent could be  potentially be a citrumelo, or different citrange.
Title: Re: F2 citrange winter hardiness trial
Post by: Citradia on February 03, 2019, 07:11:51 PM
The damage wont show right away. The leaves and green in the branches will slowly turn brown starting at tips and the dead brown tissue works its way down to the trunk and then to the ground. Ive had trees stay green until spring and then die. Look for cracks in trunks near the ground. If cracks form in trunks, probably gonna die. -15 degrees F and below freezing for a week, unprotected seedling poncirus hybrids, no. Miracle if some make it, and I would love to buy a specimen from you. I wish you the best in your endeavors.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on February 04, 2019, 03:15:35 AM
At least some of them will sprout from the roots. For me, the most promising is  the last plant, for the first three the stems are already damaged.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 06, 2019, 08:04:37 AM
Here are 2 photos showing responses of:

 # 1: F2  citrange seedlings and  the variability in cold resistance after a cold week with a low of -11.8 F. at the lowest.

 # 2: Poncirus  that hadn't dropped it's leaves.  Observed on a plant not fully hardened off.

(https://i.postimg.cc/WDnJH8ZX/IMG-32.jpg) (https://postimg.cc/WDnJH8ZX)

(https://i.postimg.cc/sGgmNbqf/IMG-20190206-065345.jpg) (https://postimg.cc/sGgmNbqf)
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on February 06, 2019, 08:33:31 AM
wow, if it stays like that you found your hardy F2 hybrid.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 06, 2019, 09:11:25 AM
Thanks, I am hopeful. Both photos were taken today and both plants were exposed to the same temperatures. I realized that there are still many weeks until April 1. when I consider all danger to be past.

I have noticed that the slight red color where the leaflets join is not an indication of cold adaptation, but rather an indication of tissue damage.

Poncirus indication of cold damage closely parallels that of the citranges. A few of the citranges appear to have hardier leaves than the Poncirus progenitor, this may only be because Poncirus would have dropped it's leaves at that degree of maturity on that position of the stem.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 08, 2019, 04:34:39 PM
This continues to be an educational experience. The local cold weather has been followed up by warmer temperatures and rain.
 A few observations:
1. Poncirus leaves and twigs that appeared to be wilted and dying have re-hydrated remarkably quickly.
2. The combination of direct sunlight and frozen soil is very dehydrating.
3. Subzero temperatures with no wind on a clear night allows a super-chilled  layer of air to form directly on top of the snow, which is very harmful, this layer was about 6" deep. I don't have record of the actual temperature of this layer, as the reading of -11.8 F. was about 30" above the snow.
4. The section of the stems above the bottom 6 inches showed considerable less damage than the lower 6".
5. The rather quick warming trend allowed some damage to be visible within days.
6. Some bark splitting is becoming apparent.
7. There will likely be additional observations over the next 6-7 weeks, perhaps longer.
8. Photos of Poncirus before warm up and after warmup and rain. This should be the same twig.
9. This Poncirus tree was planted in the early 90's.

(https://i.postimg.cc/Mf2M5R5y/IMG-20190206-065345.jpg) (https://postimg.cc/Mf2M5R5y)

(https://i.postimg.cc/fJnK8qR0/IMG-20190208-162702.jpg) (https://postimg.cc/fJnK8qR0)
Title: Re: F2 citrange winter hardiness trial
Post by: Millet on February 09, 2019, 11:34:17 AM
Kumin, excellent post, very detailed.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 15, 2019, 12:10:08 PM
After a new survey of the F2 citranges, I remain cautiously optimistic. The best looking plants remain quite consistent, although a portion of previous candidates look less promising. The best contenders are likely well under 1 percent of total plants.

One factor in their favor is the fact that our area has had record high moisture levels since July of 2018. The plants should have been well hydrated at any time the soil hasn't been frozen. An other unanticipated factor may be the black plastic film used for weed control. I suspect this will lessen the freeze/thaw effects to some degree.

There's an attached photo of a Southern Magnolia cv. 24 Below. This is included to gauge the impact our cold event had on other plants with hardiness similar to Poncirus. All cold damaged leaves will be shed during the May flush of new growth.

(https://i.postimg.cc/hXngK6sk/IMG-20190215-114205.jpg) (https://postimg.cc/hXngK6sk)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on February 22, 2019, 02:46:10 PM
Updated status of best looking F2 citranges. Some are belatedly dropping their leaves rather than shriveling on the plant. I'm edging closer to believing there will be survivors, but very few, perhaps 10 - 20 or so. March will bring it's own challenges, but the chance of getting sub-zero temperatures is decreasing.

(https://i.postimg.cc/xNz3sKQc/FEB-21-2019.jpg) (https://postimg.cc/xNz3sKQc)

(https://i.postimg.cc/8J3bBZq2/FEB-21-2019-B.jpg) (https://postimg.cc/8J3bBZq2)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 09, 2019, 05:44:12 PM
An update as winter is just starting to ease up. All photos were taken today. All plants are in ground except the first, which I potted up to allow for better protection and mobility. This plant went through all the cold  -11.8 F, etc. the rest did except for the last several nights when it had been potted.

One of the better survivors, I expect this plant to survive with stem intact. I potted the plant to allow movement to a permanent secure location. (F2 citrange)
Conestoga # 001
(https://i.postimg.cc/s1R452sM/IMG-20190309-113440-1.jpg) (https://postimg.cc/s1R452sM)

A deciduous plant I believe to be a survivor. although an F2  citrange, it resembles a vigorous Poncirus. (F2 citrange) Conestoga # 010
(https://i.postimg.cc/vxQnkcZX/IMG-20190309-064558.jpg) (https://postimg.cc/vxQnkcZX)

A cold injured Poncirus seedling,  looks worse than the very best F2 plants. (Poncirus)
(https://i.postimg.cc/30BRv17F/IMG-20190309-065014.jpg) (https://postimg.cc/30BRv17F)

20,000 - 21,000 mostly dead citrange plants. Very few of these plants are alive. (citranges)
(https://i.postimg.cc/YGDDCKL6/IMG-20190309-063621.jpg) (https://postimg.cc/YGDDCKL6)
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on March 09, 2019, 06:06:42 PM
Great! Congrats!
Mass selection always works :)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on March 10, 2019, 06:16:16 PM
Good news.
Let's hope that spring will not bring  infection at the frostbites.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 14, 2019, 12:20:03 PM
I've been monitoring both the Poncirus and Segentrange as they respond to warmer temperatures. Obviously neither one is pushing buds at present. Except for vulnerable late season growth, the Poncirus have no visible changes, just waiting on warmer temperatures in a few weeks to break dormancy. The great majority of the F2s are showing various indications of cambium failure. The outer layer of bark (rind) can be green as well as leaves. As warmer temps act on these plants the rind turns either brown in the upper portions of the stems, or splits in the lower parts of the stem. the underlying cause appears to be the same, cambium failure due to cell rupture due to freezing.

I then checked the cambium on healthy Poncirus twigs and saw the cambium was green, tight , and drier. The F2s had more succulent cambium, likely more susceptible to cell rupture under freezing conditions. 

There appear to still be a very few surviving F2s, perhaps as few as 10 plants. I am monitoring these intensely, my hope is there will be signs of growth within the coming month. In a sense there may be a race between delayed tissue failure and new invigorating growth.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on March 14, 2019, 03:06:11 PM
If you have 10 still alive, that is 10 more than I expected.  I hope so.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 14, 2019, 03:13:49 PM
This is the most impressive I've found so far, there are potentially more, but I'll probably wait until nature takes it's course a bit further.

I can't find any bark or stem defects on this one.

Conestoga # 001

(https://i.postimg.cc/CZrFDMpM/IMG-20190314-144830.jpg)

 (https://postimg.cc/CZrFDMpM)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 16, 2019, 11:42:06 AM
Here are photos showing Poncirus bud scales followed by several F2 citrange buds showing variation from citrus-like to Poncirus-like.

Poncirus bud with scales
(https://i.postimg.cc/N9ZBJ3hc/Poncirus-bud.jpg) (https://postimg.cc/N9ZBJ3hc)

F2 buds resembling Citrus

(https://i.postimg.cc/BjnkFmyc/Segentrange-bud.jpg) (https://postimg.cc/BjnkFmyc)

F2 buds on deciduous plant resembling Poncirus buds.
Conestoga # 010

(https://i.postimg.cc/vg7Dn8gK/Poncirus-like-bud-scales-on-F2-Segentrange.jpg) (https://postimg.cc/vg7Dn8gK)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on March 16, 2019, 01:36:25 PM
Looks like you have something extremely hardy. I would graft it on poncirus in order not to lose due to potential bark infection.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 16, 2019, 02:04:51 PM
Ilya, I plan on keeping reserve stock for all of the hardy specimens I find. I don't want to lose any of the hardiest genetic material. If the best specimens aren't good enough for consumption they may serve as parents in breeding more advanced individuals.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on March 18, 2019, 06:41:12 PM
I think there is also a high potential for the hardy decorative citrus with fragrant flowers and shiny autumn fruits.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 18, 2019, 06:57:49 PM
Ilya, I've considered aesthetic use, especially if the deep orange coloration might be inherited from its blood orange grandparent. There are at least another 6 trees that appear to be hardy. There are also a number of very dwarfed plants that appear unharmed. These were likely under snow cover during the coldest periods. Perhaps a purpose could be found for these also.   
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 23, 2019, 03:13:43 PM
By now the F1 seedling's lower trunk bark has turned into mush, easily pinched and slid off the underlying wood. The few remaining hardy F2 seedlings still have intact bark. .
This F2 specimen is deciduous, showed some dehydration, but no bark destruction due to freezing.
(https://i.postimg.cc/c646CKVD/pseudoponcirus.jpg) (https://postimg.cc/c646CKVD)
 this plant has a long taproot.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on March 23, 2019, 07:20:30 PM
Three nucellar F1 , one resistant zygotic F2?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 23, 2019, 07:33:30 PM
Seedling # 4 could be a non-hardy F2, or an F1. At this point the fact that a few hardy F2 specimens surpass the F1 hardiness has become very certain. The majority of the F2s were no more hardy than the F1. The partial hardiness of the F1 population was very uniform as expected.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 27, 2019, 05:14:06 PM
I apologize, this is not a very clear photo. This is another deciduous F2 citrange I found today. It doesn't show any damage at the top of the snow line. If this one isn't as hardy as Poncirus, it approaches it very closely from what I can determine. Now to find how much it differs in fruiting aspects! I hope it's not an exact replica of Poncirus.
(https://i.postimg.cc/3WYNj4jz/F2-Mar-27-2019.jpg) (https://postimg.cc/3WYNj4jz)
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on March 27, 2019, 05:34:02 PM
Now to find how much it differs in fruiting aspects! I hope it's not an exact replica of Poncirus.
(https://i.postimg.cc/3WYNj4jz/F2-Mar-27-2019.jpg) (https://postimg.cc/3WYNj4jz)
But if so offspring could be still interesting. In many years from now :)
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on March 28, 2019, 02:29:44 AM
Congratulations!  I admired the effort, but didn't think it would work.  Still a long way to go to get good hardy citrus, but you made a huge step.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 28, 2019, 05:25:10 AM
Walt, yes, it may in essence be a modified Poncirus. Which is a good approach for me, as I will need all of Poncirus's hardiness. This location is fairly near the limit for Poncirus, so introducing a bit of hardiness into conventional Citrus will not work. A better approach here is to tweak Poncirus to improve edibility.

As I stated initially, the goal is to encounter a selection that can fend for itself, if the intent were to coddle the plants, I could simply plant and protect subtropical cultivars.
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on March 28, 2019, 12:45:44 PM
What about working to design a microclimate. If you have a lot of land this may be possible. I saw one video where a guy in Montana excavated a small valley, made a lake at the bottom, with big boulders to help absorb and hold the heat, and then he could plant things on the South-facing terrace on the slope of the valley. The valley offered protection from wind, and being sunken into the earth created somewhat of a heat bank. The reflection of the sun's rays off the surface of the water also helped focus heat on the South-facing slope. This was in zone 5, but he said the temperatures at the bottom correlated to zone 7 or 8.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 28, 2019, 01:01:41 PM
I don't have the deep pockets required, but if a naturally occurring site as you describe were glazed it should definitely be possible. It probably could work on either a small, or large scale.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 30, 2019, 11:55:06 AM
Here are some somewhat clearer photos of 2 hardy F2 citranges. Most of the rows have been inspected and there will not be many more normal sized findings. There are numerous dwarf plants that don't show much damage. These F2 plants are surrounded by dead F1 plants.

Bottom focused photo.
(https://i.postimg.cc/JstGKwqF/Mar-30-2019-F2.jpg) (https://postimg.cc/JstGKwqF)
Top focus
(https://i.postimg.cc/njNy8mb7/Mar-30-2019-B.jpg) (https://postimg.cc/njNy8mb7)
Bottom focus
(https://i.postimg.cc/v1fq1Np1/Mar-30-2019-C.jpg) (https://postimg.cc/v1fq1Np1)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on March 30, 2019, 07:15:23 PM
I wonder what is a  number of F2 that are still green now?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 30, 2019, 07:32:04 PM
Ilya, there are perhaps a bit over 20 hardy dwarfs, which have limited potential. In regards to the normal sized plants, there are realistically only about 10. There are several that are brown on top and green at the bottom. At present there should be no additional new damage occurring, however I'm reluctant to give a solid number until new growth begins.
Poncirus flower buds are beginning expansion, vegetative buds are still not showing any expansion. I suspect the F2s will begin growth approximately when the Poncirus does.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on March 31, 2019, 04:02:14 AM
Ilya, there are perhaps a bit over 20 hardy dwarfs, which have limited potential. In regards to the normal sized plants, there are realistically only about 10. There are several that are brown on top and green at the bottom. At present there should be no additional new damage occurring, however I'm reluctant to give a solid number until new growth begins.
Poncirus flower buds are beginning expansion, vegetative buds are still not showing any expansion. I suspect the F2s will begin growth approximately when the Poncirus does.

I began with an initial population of 20,000+ seedlings. The seedlings are 85% nucellar and 15% zygotic, so the effective population under trial  is 3,000 plants.
[/url]
Thank you, I guess even dwarfs are worth to keep and later graft on poncirus. I have several hybrids that are growing much better on strong roots.
Have you started with 20000 seeds or 20000+ is an estimated number of seedlings?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 31, 2019, 04:14:48 AM
It's an estimate, I simply took 4,200 seeds per liter mutiplied by 5 liters of seed. I didn't physically count the trees.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on March 31, 2019, 03:04:09 PM
I'm wondering what you have against the dwarfs.  Dwarfs of many fruits are popular.  To me, surviving a winter would make them treasures.  Do dwarfs in citrus not do well?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on March 31, 2019, 03:19:49 PM
Walt, I assume they will take longer to get to the point of fruiting, and be slower to replace any growth lost to cold damage. Perhaps the fruit might be miniaturized. Once mature, they may be fine. I guess I have a preference for strong, vigorous growth.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on April 01, 2019, 02:13:23 AM
If they are dwarf because they just grow slower, then I can agree, though I repeat that having survived your winter they are worth having and breeding them.  But if they are dwarf because their internodes are shorter thyn may not be slow maturing.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 02, 2019, 08:06:54 AM
Good point, Walt. I am obviously not going to discard any of the surviving plants. I'm evaluationg what I assume they could contribute toward the goal of extreme cold hardy citrus. And I agree that their genetics should be valuable, as their progeny likely will carry hardiness when crossed with full sized specimens.
Poncirus vegetative buds have just started to swell the least bit and I expect the surviving hybrids to follow suit shortly. That will bring a moment of truth to this venture.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on April 02, 2019, 10:57:34 AM
Poncirus leaf buds have just started to swell the least bit and I expect the surviving hybrids to follow suit shortly. That will bring a moment of truth to this venture.

So the hybrids are breaking dormancy later than P. trifoliata.  That would be a good trait here, where late spring freezes are common.
Unless the hybrids are breaking late due to some cold damage.
 I am learning a lot from your experiment.  Thank you for sharing all this.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 02, 2019, 11:54:01 AM
This is an educational experience. I am impressed by the broad range of characteristics the F2 .progeny are displaying. I don't regret the large population grown. If there is ultimately one hardy seedling per two thousand plants, it should be roughly reproducible on a repeat test under similar conditions.
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on April 02, 2019, 12:03:37 PM
"it should be roughly reproducible on a repeat test under similar conditions."

If done in a zone 7 environment there should be even more survivors.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on April 02, 2019, 12:14:36 PM
Mikkel,
I wonder if you can share your experience if any  on ~500 N1tri seeds that I sent you last autumn?
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on April 02, 2019, 02:03:03 PM
I will. By now the tallest are around 10 cm high. There are others beside still just germinating.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on April 02, 2019, 02:16:43 PM
Using US 852 seedlings, with 60-70% zygotic seedlings would be good.  I might try to buy Stans whole crop next year.  From 14 fruit this year I got only 50 seedlings,  If I had sterilized the seeds, I might have had over 288.  As Ilya said, this has been a learning experience.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 02, 2019, 07:02:52 PM
Walt, I am becoming suspicious that emerging and newly emerged seedlings exposed to low temperatures can develop leaf yellowing and stunting. I had a batch of TaiTri seedlings that had a late emerging seedling among more mature seedlings. This plant developed yellow leaves, has a green stem, therefore is likely stunted at least temporarily, but not an albino. Albinos will have the same stem and leaf color.
This may be related to SoCal's experience of exposing young seedlings to low temperatures and having the seedlings develop yellowing leaves. It is possible to cold -injure immature plants without downright freezing them. I have no concerns with introducing even recently emerged seedlings outdoors if the temperatures are high enough.

When the seedlings achieve 3"-3 1/2" in height I've put them outside in the 60's F., providing it's sunny and calm.


Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on April 02, 2019, 09:27:25 PM
Where I am (Olympia, WA zone 8a) I've found that it is not really safe to bring citrus seedlings outside (even hardy varieties that have been growing inside) until the second half of March.
It is different in different places. Places like Minnesota and Massachusetts can have later Spring frosts.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on April 02, 2019, 11:10:20 PM
I expect to have to carry my plants inside a few times.  Yjey won;'t be safe for another 5 weeks.  But they need to get used to the sun gradually.  Wind too.  Basicly I'll treat them like tomatoes.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 03, 2019, 02:07:52 AM
Walt, I am becoming suspicious that emerging and newly emerged seedlings exposed to low temperatures can develop leaf yellowing and stunting. I had a batch of TaiTri seedlings that had a late emerging seedling among more mature seedlings. This plant developed yellow leaves, has a green stem, therefore is likely stunted at least temporarily, but not an albino. Albinos will have the same stem and leaf color.
This may be related to SoCal's experience of exposing young seedlings to low temperatures and having the seedlings develop yellowing leaves. It is possible to cold -injure immature plants without downright freezing them. I have no concerns with introducing even recently emerged seedlings outdoors if the temperatures are high enough.

When the seedlings achieve 3"-3 1/2" in height I've put them outside in the 60's F., providing it's sunny and calm.

60degree F. sunny calm weather (5 hours)
(https://i.postimg.cc/hhnL0swq/Tai-Tri-seedlings-April-2019.jpg) (https://postimg.cc/hhnL0swq)

Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 06, 2019, 04:42:40 PM
Some of the F2 seedlings have just begun to push buds today. It's barely noticeable, should become more obvious over the next 3 days as warm weather is in the forecast. I'll attach a photo, the expanding bud is on the upper right side of the stem. Now it becomes a wait and see game to see how many will grow.
(https://i.postimg.cc/2VpQvG0L/April-6-2019.jpg) (https://postimg.cc/2VpQvG0L)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 08, 2019, 03:52:03 PM
Photos showing the impact -11.8 deg F. had on Poncirus at this 6b location. Mature growth is fine, immature growth is being sorted out between tip die back and new growth stimulus from the roots. The damaged fall growth demonstrates the result of the sub-zero temperatures suffered at the end of Jan - beginning of Feb.

 The remainder of the photos are examples of hardy dwarf F2 citranges.
I'm favorably impressed by the cold resistance performance of a very few of the F2 population in comparison with Poncirus. Granted, there is a very low percentage, but the concept appears to be valid. Fruit edibility of the hardy specimens is quite another hurdle indeed!

Poncirus winter damage
(https://i.postimg.cc/wyw62kQS/Apr-8-2019-G.jpg) (https://postimg.cc/wyw62kQS)

(https://i.postimg.cc/njSJBhHx/Apr-8-2019-H.jpg) (https://postimg.cc/njSJBhHx)


Various dwarf F2 Citrange survivors
(https://i.postimg.cc/Nypqvj2X/Apr-8-2019-I.jpg) (https://postimg.cc/Nypqvj2X)

(https://i.postimg.cc/dDzMYX35/Apr-8-2019-A.jpg) (https://postimg.cc/dDzMYX35)

(https://i.postimg.cc/nXJ6sDv7/Apr-8-2019-B.jpg) (https://postimg.cc/nXJ6sDv7)

(https://i.postimg.cc/TprsX3ZP/Apr-8-2019-C.jpg) (https://postimg.cc/TprsX3ZP)

(https://i.postimg.cc/HrdhWCg9/Apr-8-2019-D.jpg) (https://postimg.cc/HrdhWCg9)

(https://i.postimg.cc/5YhsZhgv/Apr-8-2019-E.jpg) (https://postimg.cc/5YhsZhgv)

(https://i.postimg.cc/tYtBMmxZ/Apr-8-2019-F.jpg) (https://postimg.cc/tYtBMmxZ)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 12, 2019, 12:06:42 PM
After cutting the plants down low to the ground I was able to get a better count on the number of survivors. There should be 12 normal sized survivors, they are not all equals, some lost more stem than others. Counting even the smallest dwarfs, there are about 66 dwarf survivors. Many of these are not very impressive due to low vigor. The flags were used last summer to identify zygotic seedlings, they're no longer of much value.

(https://i.postimg.cc/t7NVSMf7/cut-plants-Apr-12-2019.jpg) (https://postimg.cc/t7NVSMf7)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 13, 2019, 09:45:06 AM
Due to the fact that the dead citrange tops have been cut off, I was able to weed the 4 rows of plants this morning. Ilya had mentioned that some of the plants would regrow from the roots. I had dismissed that possibility as each time I canvassed the plants their condition had declined further. That's no longer the case, as some plants I had dismissed as doomed are growing from a lower stem point.

So, I need to categorize the remaining plants into at least 3 categories: normal sized and stem hardy above the snow line, dwarf and hardy (likely under the snow), and normal sized, but only stem hardy under the snow during our sub-zero temperatures. As they grow out, the stem position where the new growth originates will show how stem hardy the plant was.

Unless the plants regrowing from low positions are unique in some way (monofoliate, etc.) they might not be included in the elite group of super hardy specimens for further breeding. They do warrant preservation and further evaluation, however. They might be better suited to zone 7 growing conditions.

I assume that the F1 hybrids are dead, and the under-snow hardy plants are F2 plants.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on April 13, 2019, 07:46:36 PM
As soon as your trees have leaves, you might taste them as Ilya does.  It would be great if even one lacks the Poncirus taste.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 13, 2019, 08:05:38 PM
Great idea Walt, even a second tier hardiness specimen would be of value if it had improved taste.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 17, 2019, 12:55:23 PM
A few monofoliate dwarf F2 plants. Low vigor, hardy under snow.
(https://i.postimg.cc/Dm2Fd2PZ/Monofoliate-dwarf-1.jpg) (https://postimg.cc/Dm2Fd2PZ)

(https://i.postimg.cc/PpdG44Zc/Monofoliate-dwarf-2.jpg) (https://postimg.cc/PpdG44Zc)

(https://i.postimg.cc/0rWgY7NW/Monofoliate-dwarf-3.jpg) (https://postimg.cc/0rWgY7NW)
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on April 20, 2019, 04:12:09 PM
Today I cross-pollinated my HRS 899 Variety which I got from Bernhard Vosss years ago (letter I don't know) with pollen of Citrus Lemonade, a vareity of New Zealand which tastes like sweet  Lemon imonade ;-) I will see what will happen.
(https://i.postimg.cc/9wBXnJqW/DSC00324.jpg) (https://postimg.cc/9wBXnJqW)

(https://i.postimg.cc/mzfbZ0YL/DSC00325.jpg) (https://postimg.cc/mzfbZ0YL)

(https://i.postimg.cc/4nRv7Psn/DSC00326.jpg) (https://postimg.cc/4nRv7Psn)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 20, 2019, 04:30:52 PM
Usirius, It's impressive how strongly the phenotype in the flowering branches resemble Poncirus! How hardy have you experienced it to be?
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on April 22, 2019, 01:16:53 AM
Kumin, yes if one do not know that  this is a HRS 899 F2 and would see an not flowering twig one would surely say that this is surely no poncirus hybrid....Only th flowers Show a Little difference to poncirus flowers, - one is the bigger stalk between flower and twig and another is that flowers can also accur on Little fresh growing twigs and not also directly at a brunch bud. My experiences of hardiness is -17C nin plein air without any damages. I did not have colder winters therefore I cannot say if it is also more hardy. But my hope is, if you take this instead of Poncirus as hybridization partner, on the one hand the good frost-hardness predisposition and on the other hand instead of a few bad poncirus genes a few genes of the Changsa mandarins, which are also included in the new hybrid....
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on April 22, 2019, 04:10:42 AM
Usirius,
Are you sure that it is not a poncirus rootstock that took over the HRS graft?
As I remember all HRS899 seedlings of B.Voss are evergreen.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 22, 2019, 01:21:58 PM
Usirius I couldn't remember if Poncirus flowers had a flower stalk. Since mine are in full bloom at present, I took a look at them and was surprised to see them vary from almost no stalk to a short stalk. The flowers with a stalk had fuzzy hairs on the stalks (pubescense). If your tree is a hybrid indeed, it appears to have retained many Poncirus characteristics. This should prove helpful in achieving winter hardiness. My cellphone doesn't take very good macro shots, or I'd attach several.
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on April 22, 2019, 04:29:57 PM
Kumin, interesting that your Poncirus varies from almost no stalk to a short stalk. My poncirus Show on all flowers nearly no stalk. My HRS 899 is indeed a hybrod which includes many viewable poncirus characteristics. Also the fruit show also haurs on its skin, but the shape is more like a pear, see my post of Januray this year: http://tropicalfruitforum.com/index.php?topic=30863.0 (http://tropicalfruitforum.com/index.php?topic=30863.0)  Tomorow I will smell at the flowers whether they smell otherwise than poncirus flowers do.
Title: Re: F2 citrange winter hardiness trial
Post by: Zitrusgaertner on April 22, 2019, 04:37:19 PM
Don't think this is 899. Ihave four of them and none of them has flowers like the ones you show. They look like PT-flowers. I had an early blooming PT "Kryder" that produced Flowers with pink stamens.
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on April 22, 2019, 05:16:41 PM
My one is one of several HRS 899 seedlings selections from Bernhard Voss.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 22, 2019, 05:42:42 PM
Usirius, the pink stamen color looks very similar to the pink leaf parts on your fruit photo. I have seen a bit of reddish color in autumn, but never such a distinct pink on my trees.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 22, 2019, 06:14:06 PM
The deep green F2 hybrids are breaking buds at present. All of them were later than Poncirus. Temperatures obviously play a role on timing, but overall they are 10-14 days after Poncirus. In both Poncirus and the F2 hybrids, any tissue that's olive-green rather than deep green is compromised and struggles to break buds and begin to grow. In most cases the upper stem may fail to bud out, but the lower stem will bud out. The winter we've just come through wasn't the coldest I've seen, but probably in the 75 percentile.

Olive green branches struggle to begin growth (Poncirus)
(https://i.postimg.cc/B8ZSZtpb/PT1.jpg) (https://postimg.cc/B8ZSZtpb)

(https://i.postimg.cc/Wtq21BGG/PT2.jpg) (https://postimg.cc/Wtq21BGG)

(https://i.postimg.cc/CB3p8KGj/PT3.jpg) (https://postimg.cc/CB3p8KGj)

It's amazing any segentranges survived, considering the extent of damage Poncirus shows.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 23, 2019, 07:18:48 AM
Here are 2 photos of plants I had potted up in March. These are advanced further than the ones that remain field planted. The new growth is fairly vigorous. Conestoga # 001

(https://i.postimg.cc/cgQ3Fkbg/a-April-22-2019.jpg) (https://postimg.cc/cgQ3Fkbg)

This plant doesn't appear to be particularly thorny. Photo was taken at sunrise. Conestoga # 002
(https://i.postimg.cc/F7FPJ0Yg/April-22-2019.jpg) (https://postimg.cc/F7FPJ0Yg)
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on April 23, 2019, 01:27:36 PM
Kumin,
thank you for sharing your experiences with Segentranges versus Poncirus trifoliata and also for the really impressing pictures.
I also have seen that segentranges show a longer period of winter rest than PT itself. Also Poncirus polyandra in plain air and also in greenhouse (!) stay for about 14 days longer in dormancy than Poncirus trifoliata  - can be compared with the Segentranges.
Today I put my nose to the flowers of my HRS 899 segentrange and I would sy it smells a little bit more than Poncirus trifoliata flowers do. The HRS 899 segentrange flowers are also larger than those of my Poncirus trifoliata. My Poncirus trifoliata does only show slightly pink coloured Stamens. The one HRS 899 Sgeentrange which I have is the only one which survived in 17 years. I had several phenotypes but one after the other died in the first winters. And this one which I described here survived without any damages for such a Long time. Also it survived more times early beginning of spring with  following night freezes - whew my poncirus got slightly damaged in some years. So I would propose ist hardiness is due to longer dormancy better than this of Ponirus trifoliata.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 24, 2019, 05:35:24 AM
It's interesting that Poncirus polyandra shows a bit of similarity to citranges. P. polyandra isn't considered to be a Citrus- Poncirus hybrid, but either a sister species to P. trifoliata, or perhaps ancestral to it. In some aspects it's apparently intermediate between Citrus and P. trifoliata, or perhaps closer to Citrus than P. trifoliata is.
Having suggested this, I have no experience with P. polyandra, and haven't seen it.
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on April 24, 2019, 07:03:53 AM
It is way less winter hardy than P.t.. I had diebacks at -6C at least it recovered. Usirius how is yours? Is hardy it in open ground for you?
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on April 24, 2019, 04:53:47 PM
kumin,

if I would not know that is really Poncirus Polyandra I would say that is a Citrange. The Habitus and the foliage is very similar most types of Citranges. I am still waiting for flowers and fruits. As far as I have seen there are two phenotypes....othe ne with larger foliage and the other with clearly smaller foliage.

mikkel,

I think it is more hardy than -6C. During longer enduring periods of frost I cover it with a rug - and if temperatures go down in the night below -10C I heat with a 5 W lamp. This is enough - may be this effort is more than necessary - because it did not show any damages accoridng this treatment through all the years.
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on April 25, 2019, 02:36:34 AM
@usirius okay. This encourages me to give it another try.
Do you have any picture of the two types you spoke of?
I know of a plant in a botanic garden in Germany and another one in a private collection which is already flowering. But I haven`t heared of fruits so far. No idea if these are the same plant.


Title: Re: F2 citrange winter hardiness trial
Post by: usirius on April 25, 2019, 03:18:09 AM
mikkel

I did not see the other plants you named. Maybe they all have the same origin.
By the way it is possible to post one or two photos which show the leaves of both phenotypes in the next days.
Title: Re: F2 citrange winter hardiness trial
Post by: Sylvain on April 25, 2019, 06:47:58 AM
Mine flowers every year but never gave a fruit.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 25, 2019, 12:57:00 PM
Here's a photo of the best citrandarin of a Clementine X Poncirus F1 hybrid I grew from pollination to fruiting several decades ago. I eventually left it exposed to low winter  temperatures and promptly lost it. I sent 2 scions to a cold hardy Citrus enthusiast, Major C. Collins in Tifton, GA, but doubt that he propagated it as he had health issues, including vision impairment. I strongly regret losing this tree. It's hardiness was not remarkable.

This fruit was tart, with mandarin flavor and excellent color. The peel had faint Poncirus scent, the fruit had almost no off flavors, but was as tart as an unripe mandarin.

(https://i.postimg.cc/CRbqrGG9/Citrandarin-a.jpg) (https://postimg.cc/CRbqrGG9)
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on April 25, 2019, 04:34:03 PM
kumin,

thank you so much for sharing this wonderful story with us. Although it is a pity that you have lost this particular hybrid, it encourages one to try your own crossbreeding attempts! - Years ago I read that it would be impossible to cross Poncirus trifoliata with Citrus ichangensis with Poncirus as mother. I thought, it doesn't work, it doesn't exist and had put it in my head to breed the citrus lucky clover leaf! And lo and behold, I have managed the pollination and the fruit has developed and from the few seeds has developed a clear hybrid, I have then almost the same mistake as you, I have planted the plant because it became too big for me and I thought it would immediately survive the next winter without protection. It came what had to come, it became a hard and very cold winter and the plant broke down, but before I had cut branches and made graftings, only these did not develop as beautifully as the mother plant! I didn't take care of it as much anymore...out of disappointment as it happened.  - Now I try to hybridize the HRS899 Segentrange with Citrus Lemonade. The Citrus Lemonade is a hybrid Citrus limon x reticulata and ist fruits  have a wonderful Aroma - it taste like a good tasting Lemonade. Here are some pictures of my HRS899 Segentrange - branches and flowers, I have cut it down last winter mercilessly this year because it is very vigorous and flowers relatively little. Here are some recent pictures of the leaves and flowers, also of the thorns. You can compare the habitus with your Poncirus varieties!
(https://i.postimg.cc/RqfYqcYH/DSC00617.jpg) (https://postimg.cc/RqfYqcYH)

(https://i.postimg.cc/vcsNn4RS/DSC00619.jpg) (https://postimg.cc/vcsNn4RS)

(https://i.postimg.cc/gwQM2Jqs/DSC00620.jpg) (https://postimg.cc/gwQM2Jqs)

(https://i.postimg.cc/sMfHnbgY/DSC00621.jpg) (https://postimg.cc/sMfHnbgY)

(https://i.postimg.cc/0Kqc7B4J/DSC00622.jpg) (https://postimg.cc/0Kqc7B4J)

(https://i.postimg.cc/PC630KCB/DSC00623.jpg) (https://postimg.cc/PC630KCB)

(https://i.postimg.cc/KkT0k202/DSC00624.jpg) (https://postimg.cc/KkT0k202)

(https://i.postimg.cc/T5qQ0c8N/DSC00625.jpg) (https://postimg.cc/T5qQ0c8N)
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on April 25, 2019, 04:51:42 PM
Sylvain,
interesting that also flowering is no sign for fruting! I never have seen fruits from it - also no pgotos from it. Enclosed there are some pictrues which show the two phenotypes that are existing according to my knowledge - the small leafed and the large leafed one. Which one do you have in culture?
(https://i.postimg.cc/xqBVkfgX/DSC00626.jpg) (https://postimg.cc/xqBVkfgX)

(https://i.postimg.cc/JtsW4D3w/DSC00627.jpg) (https://postimg.cc/JtsW4D3w)

(https://i.postimg.cc/dk1cCDzy/DSC00628.jpg) (https://postimg.cc/dk1cCDzy)

(https://i.postimg.cc/k2QC30QB/DSC00629.jpg) (https://postimg.cc/k2QC30QB)

(https://i.postimg.cc/s1Lsp9fD/DSC00630.jpg) (https://postimg.cc/s1Lsp9fD)

(https://i.postimg.cc/625thMGT/DSC00631.jpg) (https://postimg.cc/625thMGT)

(https://i.postimg.cc/GHsrz89P/DSC00632.jpg) (https://postimg.cc/GHsrz89P)

(https://i.postimg.cc/SnCSQ2hQ/DSC00633.jpg) (https://postimg.cc/SnCSQ2hQ)

(https://i.postimg.cc/ZvWmG0HS/DSC00634.jpg) (https://postimg.cc/ZvWmG0HS)

(https://i.postimg.cc/gwGWYgs4/DSC00635.jpg) (https://postimg.cc/gwGWYgs4)

(https://i.postimg.cc/rdT8DVV1/DSC00636.jpg) (https://postimg.cc/rdT8DVV1)

(https://i.postimg.cc/G8rHnPT1/DSC00637.jpg) (https://postimg.cc/G8rHnPT1)
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on April 25, 2019, 05:09:51 PM
Mine looks like the one on the 4th picture. It comes originally from BG Darmstadt.
I just tried to find the pictures of the flowering plant  to see if it is different but I can not find the link. Maybe later...
usirius do you have both types?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on April 25, 2019, 07:31:19 PM
Beautiful pictures, the petioles are quite elongated. The entire leaf has a pointed, longer aspect. P.trifoliata has a shorter, blunter look to the leaves. One of my citranges superficially had some resemblance to these photos.
(https://i.postimg.cc/rzH4y70p/IMG-20180811-154404.jpg) (https://postimg.cc/rzH4y70p)
Title: Re: F2 citrange winter hardiness trial
Post by: Sylvain on April 26, 2019, 09:27:35 AM
Mine looks like the first and last picture. It comes from Horst.
The folioles are very thin.

(http://pafranceparamoteur.free.fr/datas/perso/Agrumes/Poncirus%20polyandra%20fleur3.jpg)

And this is a drawing of the original plant:

(http://pafranceparamoteur.free.fr/datas/perso/Agrumes/poncirusPolyandra.jpg)

We can see that the one with thin leaflet is the right one. The other could be a hybrid.
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on April 26, 2019, 10:17:22 AM
Found the link: This is the plant from Horst. The same as Sylvains.

http://yuccaundanderefreilandsukkulenten.xobor.de/t1071f9-Erstbluete.html (http://yuccaundanderefreilandsukkulenten.xobor.de/t1071f9-Erstbluete.html)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on April 26, 2019, 10:37:29 AM
Usirius,
- Years ago I read that it would be impossible to cross Poncirus trifoliata with Citrus ichangensis with Poncirus as mother.
Last year just out of fun I  pollinated 7 castrated  Swamp Lemon Poncirus flowers with C.ichangensis IVIA358 pollen. Five fruits yielded 178 seeds, giving 224 seedlings. At least 64 of them were clear hybrids, with shape of their leaves intermediate between those of poncirus and ichangesis.

Now I try to hybridize the HRS899 Segentrange with Citrus Lemonade.

Strictly saying HRS899 seedlings from B.Voss are segendarins (second generation citrandarins), not segentanges ;D
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on April 26, 2019, 11:22:34 AM
Ilya11,

that sounds interesting what you did with crossing Poncirus and ichangensis also with success. So it is possible - against the things what I have read in litertaure many years ago. Did yiu have been able to have plants which Show leafes with four similar large parts ?

Yes and you are right.....the F2 generation of HRS899 are Segendarins!


Sylvain,

thank you for sharing the Picture of you. You mentioned my Picture No. 5 (not 4) ? So this is the larger foliated phenotype. The smaller foliated phenotype seem to be more frost hardy. Both phentotypes have been discovered many years ago in the Yunnan Region in China by a friend of me - and buddhist Monks told him that both are species of P. Polyandra. So I believe that there are Minimum  two phenotpyes existing. My friend did only see one fruit in rather grat tree. One aother intersting Thing is that the origin great trees Show succers at their roots!


mikkel:

thanks for the link for the picture. It Shows the larger foliated phenotype which I also have.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on April 26, 2019, 11:56:22 AM
Did yiu have been able to have plants which Show leafes with four simalr large parts ?
Not really, most have the smaller back side leaflets like this:

(https://b.radikal.ru/b20/1904/a0/a9ff96052cfa.jpg) (https://radikal.ru)
Title: Re: F2 citrange winter hardiness trial
Post by: Sylvain on April 26, 2019, 12:16:16 PM
I said "first and last picture." that is #1 and #12.
#4 is ok too but not #5.

You can read more here:
http://www.agrumes-passion.com/poncirus-citranges-porte-greffes-rustiques-f67/topic123-15.html (http://www.agrumes-passion.com/poncirus-citranges-porte-greffes-rustiques-f67/topic123-15.html)
Title: Re: F2 citrange winter hardiness trial
Post by: Sylvain on April 26, 2019, 12:24:28 PM
Error, sorry.
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on April 26, 2019, 04:13:22 PM
Ilya11,

thank you for the picture of your crossing. I will show you a picture of mine shich has more narrow leafes. The young leafes seem to grow to 4 similar leafes but during growing the relation between the three leafes and the stalk gets different.

Sylvain,

thank you for clarifiying - sorry this has been my error.
Nevertheless I believe that yours seem to be the larger foliated phenotype?
Can you please measure on some typical leafes the length of  the middle leave and let me know?
Title: Re: F2 citrange winter hardiness trial
Post by: Sylvain on April 27, 2019, 08:52:04 AM
Here it is:

(http://pafranceparamoteur.free.fr/datas/perso/Agrumes/Poncirus_Polyandra_leaf.jpg)

Leave 8.7 cm, middle leaflet 6.3 cm, petiole 2.4 cm, lateral leaflets 2.6 cm and 4 cm.
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on May 02, 2019, 01:03:11 AM
Ilya11,

enclosed two pictures of young leafes and one picture of one adulte leafe of my crossing -  most other adulte leafes are lost during winter:

(https://i.postimg.cc/ZByhYqSp/DSC05785.jpg) (https://postimg.cc/ZByhYqSp)

(https://i.postimg.cc/Y4PHwWJt/DSC05786.jpg) (https://postimg.cc/Y4PHwWJt)

(https://i.postimg.cc/K1ZF7FPh/DSC05787.jpg) (https://postimg.cc/K1ZF7FPh)

sylvain,

thank you for picture, it seem so that you have the same large leafed P.P. I also have - you can see this on the following two pictures of my plant


(https://i.postimg.cc/wRHbKxT6/DSC05789.jpg) (https://postimg.cc/wRHbKxT6)

(https://i.postimg.cc/672Pn1mN/DSC05790.jpg) (https://postimg.cc/672Pn1mN)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on May 02, 2019, 04:16:41 AM
Usirius,
Your hybrid has very few  features from papeda. Petiole and the proportion of adult leaflets are very close to those of poncirus. What clone of C.ichangensis have you used?
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on May 03, 2019, 03:05:01 AM
Ilya11, I took the pollen from a Citrus ichangensis which I purchased ad nursery Otto Eisenhut in San Nazzaro (Suisse) many years ago. Otto Eisenhut propagated C. ichangensis from a ichangensis-tree of Dr. E. Frey. This tree of Dr. E. Frey survived planted decades of years in plein air without any protection in a garden in Ronco s/A close to Lago Magiore. So it is not a special cultivar but one which has shown a good frost resistance all the yeras in - I would say USDA zone is between 8 and 9.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on May 03, 2019, 04:31:07 AM
Thank you Usirius,
Eisenhut currently has three clones of C.ichangensis: Clone "Klock" (Z269), IVIA (Z189 ) and Z83 which is marked as exceptionally frost resistant.
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on May 03, 2019, 10:35:29 AM
Ilya11,
thank you for update concerning Eisnhut portfolio. I bought my C. ichangensis for about 25 years ago, in this time Eisenhut only had the one C. ichangensis variety from which I took the pollen for sale. I think that this one is the Z83. Klock did in this time no material exchange with EIsenhut. And the IVA Clone found its way to Einsehut earliest I would say 10-15  years ago.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on May 03, 2019, 11:43:47 AM
I bought my first C.ichangensis from B.Voss in 2001, it was listed as N2 (resistant to -12C) and originated from Florida arboretum. I believe O.Eisenhut and B.Voss exchanged many varieties at this time. I lost this plant after a warm winter followed by late spring frost of -9C.
Do you still have your original  Eisenhut ichangensis?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 04, 2019, 07:56:09 PM
Here are current photos of the F2 segentranges. A few are from plants potted in March, but most are from plants still in ground at present. Except for the small seedlings, the remainder have survived -11.8 deg F. in Jan/Feb of 2019. The shorter plants had some natural protection provided by snowfall.

A vigorous, deciduous specimen. No protection provided at any time. Conestoga # 011
(https://i.postimg.cc/0r8C1C5N/May-4-2019-a.jpg) (https://postimg.cc/0r8C1C5N)

A unique plant that had zero dieback, not especially vigorous (small leaves). This plant was clearly taller than the snow cover.
(https://i.postimg.cc/QVxcyxS9/May-4-2019-b.jpg) (https://postimg.cc/QVxcyxS9)

2 fairly vigorous specimens.
(https://i.postimg.cc/nMP9SKCg/May-4-2019-c.jpg) (https://postimg.cc/nMP9SKCg)

The large pots are F2 hybrids potted in March, the remainder are 2019 seedlings of several cold hardy selections.
(https://i.postimg.cc/JswDM13Q/May-4-2019-d.jpg) (https://postimg.cc/JswDM13Q)

A vigorous F2 unprotected specimen.
(https://i.postimg.cc/VSmJ0DVr/May-4-2019-e.jpg) (https://postimg.cc/VSmJ0DVr)

2 additional specimens.
(https://i.postimg.cc/k6hGZ9XK/May-4-2019-f.jpg) (https://postimg.cc/k6hGZ9XK)

There are quite a few more small surviving plants that are less photogenic. Within a month I hope to begin grafting some of most mature specimens unto P. trifoliata.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on May 05, 2019, 04:15:07 AM
Congratulations!
Actually you have been lucky to have such extreme winter for a rapid selection.
I am rather upset with the absence of real cold this season, too many seedlings are still alive ;D
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 05, 2019, 07:02:13 AM
It's interesting you mention having too many survivors due to inadequate cold to eliminate marginally hardy plants. As I explain my goals to people in my community, the majority tell me "what a shame so few survived" not realizing the objective is to eliminate all but the very hardiest specimens. Some get the long version, and others get the short version, in the explanation of the details.

I have a family member that lives 200 miles south of me in zone 7b. I may trial clones of some of the better F2 specimens to see the results in that area.

The winter has indeed been severe, affecting local Kaki persimmons severely, delaying leaf emergence, and, or actual killing established trees.
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on May 05, 2019, 10:54:34 AM
kimon,

thank you for sharing the result of the nseleciton. I agree fully to Ilya11 and you that main objective it to select only those specimens who survive properly also in very stron winter seasons. In the past I selected specimens of Citrange and Segentranges surviving some yeras with less to no damage and than they died in an more extreme winter - at -17C or at .20C which U already had here. And some died after surviving such an extreme winter after being awake by a slight night freeze....... So all thos specimens are worthless and as more early as one can find out this one is able to concentrate the work on few seedlings and onbe also has again room for testing new prduced hybrids. I can confirm your experience - that in winters which damaged my  kakis also many citrus selections of mine has been damaged, so I think that Kaki (also Trachycarpus, Olea, Pistacia....) damages can be used as well sign concerning finding out well surviving citrus specimens. Only Problem may be I think that those specimens have a grater part of poncirus - also regarding fruit properties.

Ilya11,
know the Problem you have....also here since I would say 5 years we did not have a very hard winter any more. Well on the one side...my kakis and other exoctic plants lile Trachycarpus, Pistacia. Olea ....show no damages so Long. Good for the development of the individual plants...bad for knowing more alate which specimens are not worthy to keep them in the future.

To your question concerning C. ichangensis....I did not keep itbecause of its weak fruit quality.
.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on May 05, 2019, 12:46:13 PM
Completely agree with Usirius that each winter presents different challenges for citrus resistance.
Basically still, there are two different scenarios: gradual late autumn cold acclimatization followed by either a dry freeze or a moist heavy snow.
The third challenge is a late winter/spring rise of temperatures broking dormancy  followed by an abrupt freeze.
Fully hardy hybrids other than having an ability to resist extremely low  temperatures and  burn by snow should have a very deep dormancy to avoid an abrupt winter return.
 
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on May 05, 2019, 02:34:46 PM
To your question concerning C. ichangensis....I did not keep it because of its weak fruit quality.
I think C. ichangensis may have much value for hybridization because it's the only fruit that does not have poncirus bitterness and is still fairly cold hardy. If you crossed it with something like citrange you might get something useful.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 05, 2019, 03:33:43 PM
SoCal, I have several years to plan where to go from this point. I've started TaiTri and Citrumelo seedlings and will evaluate their hardiness in the meantime. Any potential pairing of parents should offer either increased hardiness, or edibility. Hardiness is becoming apparent in the F2 survivals, but  palatability is unproven. I don't plan on re-introducing tender Citrus from this point forward. Therefore improvements in flavor would need to come from the very hardiest non-poncirus sources as you suggest, or from genes within hybrid populations. After the plants grow additional foliage, I will be able to taste-test them for Poncirus off-tastes as Ilya does.

If I'm very fortunate a few of the plants might have edible fruit. In the past when I created Citrandarin hybrids, there was one edible (albeit sour) individual in the first generation. My understanding is that having mandarin parentage dramatically reduces the Poncirus off-flavors. Ruby blood orange, as the Citrus component of these F2 citranges likely won't provide such a benefit.
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on May 05, 2019, 03:48:52 PM
If I'm very fortunate a few of the plants might have edible fruit.
Hybridizing very hardy citrus that is truly good eating quality is going to take a long time.
I would count yourself lucky if you are able to achieve a hybrid that can survive in your winters and doesn't have poncirus bitterness, even if it might not be good fruit quality.

Perhaps someone in the future could later take your achievement and use it to hybridize a better hybrid in the future.
Incremental progress. If you achieve a significant improvement, even if it might not be what you had hoped for, don't throw it away.
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on May 05, 2019, 04:05:34 PM
I've started TaiTri and Citrumelo seedlings and will evaluate their hardiness in the meantime.
There's no chance Citrumelo is going to survive for you in 6b. TaiTri might.

I do think Citrumelo is, generally, just a bit hardier than Citrange, but you are going to need a lot of seedlings to show any that exhibit exceptional hardiness, similar to the citrange trial you have already carried out.

Considering that you are in 6b, I could see the reluctance to use C. ichangensis in hybridization. Even C. ichangensis simply isn't hardy enough where you are.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 07, 2019, 09:04:05 AM
One of the surviving Segentranges has ragged edged central leaflets. They vary a bit, but are generally notched and have uneven leaf tips. This is one of the more vigorous plants, hopefully the asymmetrical leaves won't won't be matched with asymmetrical flowers. In my previous work on citrandarins there was some correlation between leaf and flower symmetry. A few had petaloid anthers in the flowers.
(https://i.postimg.cc/CB0X81fN/Notched-leaf.jpg) (https://postimg.cc/CB0X81fN)
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on May 12, 2019, 03:28:53 PM
If I'm very fortunate a few of the plants might have edible fruit.
Hybridizing very hardy citrus that is truly good eating quality is going to take a long time.
I would count yourself lucky if you are able to achieve a hybrid that can survive in your winters and doesn't have poncirus bitterness, even if it might not be good fruit quality.

Perhaps someone in the future could later take your achievement and use it to hybridize a better hybrid in the future.
Incremental progress. If you achieve a significant improvement, even if it might not be what you had hoped for, don't throw it away.


As always, we have similar goals but are using different methods.  So far you have guessed right more than I have.  I have learned much from your results and modified my plans for the better.  Many thanks.

That said, I will be bringing in new breeding stock of pure citrus. 

I'll use Flying Dragon X Seedless Kishu.  Flying Dragon as it is my oldest P. trifoliata that gives a good percentage of zygotic seeds.  Seedless Kishu for its dominant gene for seedless.

I want to use Flying Dragon X Blood oranges.  Blood oranges have been said ,elsewhere on this forum, to have no sourness.  While I want some sourness in my citrus  fruit, all my 1/2 and 1/4 Pt hybrid fruit are much too sour.  IF the "no sour" in blood oranges is due to a single gene, then F2 Flying Dragon x Blood might include no sour or less sour fruit.  I think that (Clem x tri) x Clem juice mixed with a no sour trifoliata hybrid juice might give a good drink.

Also, as I've said elsewhere, I'd like to remake all the citrus X P. trifoliata crosses using Laaz's precocious P. t and using P.t like Poncirus+.

If anyone has the trees to make any of these crosses, but no room to grow them out, make the crosses and I'll make room for the seedlings.  And I'll share budwood as soon as possible.
Title: Re: F2 citrange winter hardiness trial
Post by: Walt on May 12, 2019, 03:32:35 PM
SoCal, I have several years to plan where to go from this point. I've started TaiTri and Citrumelo seedlings and will evaluate their hardiness in the meantime. Any potential pairing of parents should offer either increased hardiness, or edibility. Hardiness is becoming apparent in the F2 survivals, but  palatability is unproven. I don't plan on re-introducing tender Citrus from this point forward. Therefore improvements in flavor would need to come from the very hardiest non-poncirus sources as you suggest, or from genes within hybrid populations. After the plants grow additional foliage, I will be able to taste-test them for Poncirus off-tastes as Ilya does.

If I'm very fortunate a few of the plants might have edible fruit. In the past when I created Citrandarin hybrids, there was one edible (albeit sour) individual in the first generation. My understanding is that having mandarin parentage dramatically reduces the Poncirus off-flavors. Ruby blood orange as the Citrus component of these F2 citranges likely won't provide such a benefit.


Sorry.  This was the quote that I meant to have in my post above.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 12, 2019, 04:46:07 PM
One thing to contemplate is if truly hardy edible Citrus is developed for climate zone 6b, the initial threshold for palatability may be set rather low. There will be no competing cultivars, that situation will likely change if the first cultivars can be utilized in further crosses to improve and refine flavors. Developing the initial cultivar with acceptable fresh eating quality could get the ball rolling in this respect. At this point the theoretical, as well as practical upper limit for cold hardiness is found in P. trifoliata. I don't think this upper limit is likely to change as there isn't any close relative that can offer greater hardiness. At best, advanced kumquat crosses might genetically contribute prolonged dormancy.

Ilya has stated that Poncirus shows heterozygosity for cold hardy genes. Perhaps, an improvement in hardiness could be made by selecting for homozygosity for these factors.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on May 12, 2019, 05:27:10 PM
If I will have the second wave of flowering of Poncirus+ trifoliata this summer, I could pollinate it with the pollen of acidless orange Gosset that I have.
Selection of hardy F1 citranges and crossing  between them  can  eventually give acidless hybrids without internal oils  closer to PT in winter resistance. It is a little bit out of my current goals so may be I can share the eventual  F1 seeds with you.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 12, 2019, 06:20:37 PM
Great idea, Ilya, Poncirus has plenty of acidity to contribute to it's progeny.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 12, 2019, 07:05:23 PM
I have been a bit less active in posting lately, as I have potted 130 Poncirus seedlings in preparation for propagation of the F2 seedlings.
One of the germinating seedlings planted several weeks ago snapped the stem off during emergence due to the cataphyllic leaves not releasing from the planting media.

The seedlings were in a humidity dome and the severed apical stem didn't desiccate. On an impulse I grafted it on a 6 year old Poncirus tree (fruiting for the first time). Due to chilly weather it hasn't grown much, but it's apparently succeeded. I have previously grafted newly emerged seedlings successfully. The less differentiated tissue appears to take rather well. These aren't grafts in the truest sense, the rootstock is prepared as for budding, the seedling scion is inserted as a thin sliver 1/16 - 1/8 inch (2.5mm). If I find time, I will try to take photos of the process at some point.

Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 15, 2019, 06:33:39 PM
Here is one of the hardiest plants in the group of survivors. Although not the most vigorous plant, it is unique for several reasons. This plant is growing out to the tip, with no dieback. The upper third of the plant is thornless, which is unusual considering it's hardiness. I will be propagating and monitoring this plant closely, despite it's flaws. Getting extreme hardiness combined with low thorniness is one step in the right direction. I'm interested in it's fruiting behavior and qualities. This plant also exibits prolonged dormancy/delayed spring leaf emergence.

(https://i.postimg.cc/d7TDjdV5/5-15-2019-c.jpg) (https://postimg.cc/d7TDjdV5)
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on May 15, 2019, 08:28:52 PM
You're probably already doing this, but I'd keep some extra cuttings in case an unusually harsh Winter kills everything outside.
The trial can move along a lot faster if spare cuttings are kept of each cultivar. One will be growing fast inside, while being simultaneously tested outside.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 15, 2019, 10:59:53 PM
There are 130 Poncirus seedlings prepared and waiting for budding/grafting in June. The more desirable plants will be cloned several times. I have a geodesic frame I plan on covering during the winter with film, using water as a heat sink. There should be no need for artificial heat, provided there's adequate insulation on the north side of the structure.

This building should serve as a repository for all the clones. There are a number of seedlings (TaiTri, citrumelos, etc. from this spring's new acquisitions,these need to be cold tested to earn a place among the F2 segentranges. My intention is to have secure backup of each clone on hand.
Title: Re: F2 citrange winter hardiness trial
Post by: lebmung on May 16, 2019, 04:32:53 PM
There are 130 Poncirus seedlings prepared and waiting for budding/grafting in June.

how old are your seedlings?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 16, 2019, 04:39:45 PM
1 to 3 years old. I planted a few thousand additional seeds again this spring . I don't want to be short when I need them.
Title: Re: F2 citrange winter hardiness trial
Post by: lebmung on May 17, 2019, 06:55:47 PM
That is a lot of planting. Why do you sow in November when you get the seeds then you have 90% germination rate. This year I am planning also to sow 1000 seeds.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 17, 2019, 08:52:40 PM
I used an easy method, in the end of March I gathered fruit that had fallen in the autumn/early winter. After soaking them in water and squeezing/manipulating the fruits, the seeds separated from the pulp. I disinfected the seeds with Sodium  hypochlorite, then rinsed them and planted immediately. Due to recent cool temperatures, seedling emergence has only been evident for the last week. Germination appears to be satisfactory.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 18, 2019, 12:02:25 PM
This is a newly emerged seedling grafted to a branch mature enough to fruit. This type of graft has worked well for me. The rootstock bark is cut downward about 3.5 cm long trying not to cut into the underlying wood. The scion is prepared by selecting a thin twig and slicing off the skin of the bark on both sides, trying to not remove more of the cambium than necessary(exposing, but not removing the cambium). (It could be phrased as shaving off the epidermis on the 2 sides at the contact points.) These grafts have performed very well for me, perhaps because of the extensive cambium contact. The parafilm doesn't serve any purpose at this point other than indicating the graft location. The actual graft is lower on the stem than the parafilm.
(https://i.postimg.cc/N9kYv2wx/IMG-20190518-115029.jpg) (https://postimg.cc/N9kYv2wx)

 Waiting until these stems are mature enough to use as scions. (https://i.postimg.cc/D4fhvfv3/IMG-20190518-115146.jpg) (https://postimg.cc/D4fhvfv3)

TaiTri seedlings growing nicely. (https://i.postimg.cc/Rqv4Qdcp/IMG-20190518-115210.jpg) (https://postimg.cc/Rqv4Qdcp)

Citrumelos coming along well. (https://i.postimg.cc/SJs4HK1W/IMG-20190518-115225.jpg) (https://postimg.cc/SJs4HK1W)

Surprise Magnolia grandiflora discovered growing under Poncirus. The first seedling in 22 years!  (https://i.postimg.cc/cr9xJ3t9/IMG-20190518-115256.jpg) (https://postimg.cc/cr9xJ3t9)
Title: Re: F2 citrange winter hardiness trial
Post by: lebmung on May 19, 2019, 04:11:43 PM
I used an easy method, in the end of March I gathered fruit that had fallen in the autumn/early winter. After soaking them in water and squeezing/manipulating the fruits, the seeds separated from the pulp. I disinfected the seeds with Sodium  hypochlorite, then rinsed them and planted immediately. Due to recent cool temperatures, seedling emergence has only been evident for the last week. Germination appears to be satisfactory.

I prefer sow them in the fall, by the time spring comes they are 8-10 inches high, this way you extend the season to one year more, because PT stops growing at the end of September. A hormone mechanisms tell him to go dormant. Sodium hypochlorite is toxic and might kill some seeds I use peroxide.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 20, 2019, 05:40:02 PM
Here is a clearer photo of the 40 cm tall F2 Segentrange with no dieback after a low temperature of -11.8 deg. F. (-24.3 C) in the end of January of 2019. This plant is slow to break buds. It has a number of faults, such as low vigor and very slender growth. I'm not finding much correlation between vigor and hardiness, perhaps the reverse. One benefit of vigor is quicker recovery from cold injury, but vigor doesn't appear to provide much initial protection. Although this plant has short thorns near the base, the upper level is thornless.

I may try to use this plant in further breeding, if it matures and flowers in a timely manner. The partner should probably be one of the most vigorous specimens available.
(https://i.postimg.cc/0b0yYzNB/No-dieback.jpg) (https://postimg.cc/0b0yYzNB)
Title: Re: F2 citrange winter hardiness trial
Post by: hardyvermont on May 20, 2019, 09:28:42 PM
"Surprise Magnolia grandiflora discovered growing under Poncirus. The first seedling in 22 years!"

What variety is the parent?
Title: Re: F2 citrange winter hardiness trial
Post by: Zitrusgaertner on May 21, 2019, 03:31:37 AM
Usirius, no, Bernhard has been a little bit out of Citrus in the last years. He has lost most of hir plants after a storm had damaged his greenhouse. I have spent some time with him last summer and last weekend I met him in Vienna at the "Wiener Zitrustage". I wonder what 899-variety you have. The rather hairy fruits look strange to me. I have 4 899-F2-hybrids but only with 2 of them I am sure about the correct marking. I have (for sure) 899A and 899J and (quite sure) 899F and (don't know) 899E or H. All are blooming. 899A has sweet, mandarin-like fruits. 899J did not bear fruits yet and the fruits of the rest are not edible.
899A is monofoliate, 899J aswell, F and H Show trifoliate leaves, but very few with the years.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 21, 2019, 04:24:08 AM
Hardyvermont, Edith Bogue is the seed parent. It's likely also the pollen parent, but there's a 24 Below tree nearby, that could be the pollen parent.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 25, 2019, 04:32:06 PM
I compare the severity of winter cold by the affect on various cold sensitive woody plant species. I have already mentioned this winter's damage on Kaki persimmons (2 severely injured back to the trunk and major branches, 2 killed outright) Bamboo, cold injured  to the ground , Mimosa, delayed growth, but not killed. Today, I cut down  my dead Crape Myrtle that hadn't suffered much injury in the past 12 years, or so.
These 4 trunks were killed to the soil level. These trees had winter top-killed in the past, but not in the last decade.
I previously mentioned the need to classify the F2 survivors into 3 categories:

1. Stem survival above snow level,

2. Stem survival within snow height.

3. Stem survival within snow height-dwarf.

I now need to add a 4th category: survival from roots below soil level. These are obviously less hardy, and will be observed for unusual or outstanding characteristics.

2018-2019 was the most injurious winter in at least a decade, as these crape myrtles were killed to the ground.

My oldest Poncirus tree and offspring are in the background.


(https://i.postimg.cc/vggVKhdg/Crape-Myrtle-dead-to-ground.jpg) (https://postimg.cc/vggVKhdg)
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on May 25, 2019, 07:22:38 PM
I wonder what 899-variety you have. The rather hairy fruits look strange to me. I have 4 899-F2-hybrids but only with 2 of them I am sure about the correct marking. I have (for sure) 899A and 899J and (quite sure) 899F and (don't know) 899E or H. All are blooming. 899A has sweet, mandarin-like fruits. 899J did not bear fruits yet and the fruits of the rest are not edible.
I have a few seedlings of US 852 as well, so I'm assuming that would be in the same category. (They're just small right now)
They were grown from fruit from Stan's farm, so I'm hoping there may be a chance one or two of them could turn out to be some sort of hybrids. (Thought I think that's probably wishful thinking)

US 852 is probably the only hybrid that's fully hardy well into zone 7 (might possibly even be able to survive borderline 6b as long as it's not too far north).
Title: Re: F2 citrange winter hardiness trial
Post by: lavender87 on May 27, 2019, 04:13:43 PM
  All effort would be meaningless if we fail to accelerate the ripening time, so their fruits can be harvested before the first frost of winter arrival. Even in zone 8a where I live, people growing Thomasville citrangequat had problems with ripening time of the year. Some versions of citrangequat trees do offer good taste of fruits when fully riped. I know some stubborn folks would upset to hear about unknown hybrid of citrangequat because of their outdated knowledge that citrangequat is a genetic dead end. If someone have questions about whether or not citrangequat could have some zygotic seedling, they can contact Stan Mckenzie to ask about its seedlessness.

   The original Thomasville Citrangequat fruit was described as being seedy and very tart, with mainly trifoliate leaves and thorny, but some of Thomasville citrangequat tree from Stan offered nearly seedless fruits and some have mix foliate with very few trifoliate leaves, some trees even thornless, eventhough they were all come from Stan Mckenzie.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on May 27, 2019, 04:45:54 PM
Thomasville is flowering several times in my climate. Spring bloom is giving seeds when cross pollinated by other hybrids in the garden, while during the early July flowering there is usually no other citrus to pollinate it.
This gives seedless fruits. Thomasville seeds are giving only  nucellar seedlings, cross pollination is just necessary to induce  them.
Stamens of Thomasville flowers contain some fertile pollen grains, especially during hot weather. I managed to produce several dozens of its hybrids with 5star citrumelo.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 27, 2019, 05:57:01 PM
Ilya, when is 5* ripening in your location? Are your 5* X Thomasville seedlings vigorous?
Title: Re: F2 citrange winter hardiness trial
Post by: eyeckr on May 27, 2019, 10:57:04 PM
Amazing graft Kumin and good luck with all your trials.

Lavender87 you mention ripening of Thomasvilles. As long as they are sized up and juicy I've always used them like a lemon or lime substitute while they are green and they taste fine. Are you trying to get them to ripen until they are totally orange and eat them whole like a kumquat?
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on May 28, 2019, 03:12:54 AM
Ilya, when is 5* ripening in your location? Are your 5* X Thomasville seedlings vigorous?
Usually 5star starts to bloom at the end of April, fruits are yellow by November 10. But  if you keep them after  the harvest until January they are much less acid.

5starXThomasville seedlings are very variable, from the first batch of 20, only three are still alive after two years in the ground.
Last year pollination gave 40 zygotes, only three are as vigorous as nucellar 5stars

(https://a.radikal.ru/a30/1905/36/06752395b19a.jpg) (https://radikal.ru) 
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on May 29, 2019, 02:16:34 PM
Ilya, I believe you have referred to 5*'s impressive storage life previously. What storage temperature has worked best for you? I haven't been very impressed by Poncirus storage duration in the past. It appears 5* is considerable better.
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on May 29, 2019, 02:30:58 PM
I stored its fruits both in a basement with temperatures around +12C as well as at room temperature. Even in March they are mostly undamaged, juice is less sour and actually more abundant than just after a harvest in November, since the flesh is loosing its hardness.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 08, 2019, 07:18:43 PM
Presently I am preparing Poncirus seedlings to be used as rootstock under segentrange scions. As soon as the larger seedlings begin new growth they have overcome transplanting shock sufficiently to use as rootstock. The smallest need to grow a good bit in size before use.

There are maybe 800 seedlings not potted at present. 300 + small ones are potted and 130 larger ones are potted of which about 12 have been grafted.

There's a lot of work to be done by autumn of this year.

300 plus recently potted Poncirus seedlings.
(https://i.postimg.cc/SnMf0WKb/IMG-20190607-131613.jpg) (https://postimg.cc/SnMf0WKb)


Several hundreds of this year's Poncirus seedlings - not potted. Sand used as weed control.
(https://i.postimg.cc/67xLBy72/IMG-20190607-131634.jpg) (https://postimg.cc/67xLBy72)

1-3 year old Poncirus seedlings. As they flush new growth, they should be ready to graft.
(https://i.postimg.cc/xc73FsnP/IMG-20190607-131702.jpg) (https://postimg.cc/xc73FsnP)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 08, 2019, 07:39:00 PM
Poncirus contains several gene regions responsible for its freeze resistance and its genome is highly heterozygous. That is why  F1 hybrids with citrus are showing a large variation for winter hardiness.
Three hundreds of its F1 hybrids with very frost sensitive pummelo show a wide distribution of freeze damage.

 article ([url]http://journal.ashspublications.org/content/128/4/508.full.pdf[/url])

([url]https://b.radikal.ru/b13/1902/bb/5a2a6f76c8cf.jpg[/url]) ([url]https://radikal.ru[/url])

Quite possible that C35 citrange inherited a rather unfavorable set of gene alleles from its poncirus parent explaining its poor winter performance.


Ilya, considering that C-35 citrange may not include all of the genes providing cold hardiness found in Poncirus, I plan on not only sampling and testing within the segentrange progeny that have survived, but also crossing with the hardiest Poncirus hybrids approaching edibility that are available. I will be winter testing 5* Citrumelo and TaiTri this winter. If their hardiness approaches that of my survivors, they will be considered as parents.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 08, 2019, 07:52:10 PM
The good and the bad:
This clone is the only one to show zero dieback after a low temperature reading of -11.8 deg. F in late January of 2019.
A defect of this clone is the failure to green up properly this spring. There is also overall low vigor. Regular foliar nutrient feeding has been started. This plant may not do well on it's own roots.

If it is possible to overcome it's defects, this plant may be used for breeding purposes, due to it's excellent cold hardiness.
(https://i.postimg.cc/gwqcnkDB/IMG-20190608-062358.jpg) (https://postimg.cc/gwqcnkDB)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 14, 2019, 07:13:25 AM
A few current photos:

69 survivors selected for further evaluation - some have serious defects and may not be used for further breeding.
(https://i.postimg.cc/2VLxwHMW/69-Selected-Survivors.jpg) (https://postimg.cc/2VLxwHMW)

Conestoga # 011
One of the hardiest specimens - all but 1 twig removed as scions for grafting.
(https://i.postimg.cc/cKh7HPgp/011.jpg) (https://postimg.cc/cKh7HPgp)

2 Monofoliate survivors - appear rather Citrus - like. Conestoga # 058 and Conestoga # 064
 (https://i.postimg.cc/r0z4psL4/Monofoliate-June-14-2019.jpg) (https://postimg.cc/r0z4psL4)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 14, 2019, 10:09:20 AM
A variegated Citrange I found recently.
(https://i.postimg.cc/WhKH6Ppg/IMG-20190612-192333.jpg) (https://postimg.cc/WhKH6Ppg)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on June 14, 2019, 12:30:03 PM
Does not look like albino chimera, probably either some root deficiency or a viral infection.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 14, 2019, 02:48:24 PM
I tend to agree with you, Ilya. It lacks the layered look of chimeras. Several plants display yellow new growth that improves with foliar nutritional sprays. We have experienced a wet, chilly, prolonged spring to this point and there may be problems getting nutrients to the foliage.

Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 14, 2019, 05:06:05 PM
An example of defects: these two plants suffered bark freezing that healed and the plants recovered, but still are likely to carry the susceptibility.
Conestoga # 003
(https://i.postimg.cc/wRs0Zvgh/IMG-20190614-170042.jpg) (https://postimg.cc/wRs0Zvgh)

(https://i.postimg.cc/1g97XsrQ/IMG-20190614-170141.jpg) (https://postimg.cc/1g97XsrQ)
Title: Re: F2 citrange winter hardiness trial
Post by: Laaz on June 15, 2019, 07:43:51 AM
A variegated Citrange I found recently.
(https://i.postimg.cc/WhKH6Ppg/IMG-20190612-192333.jpg) (https://postimg.cc/WhKH6Ppg)

That's not variegation. Ilya is correct.
Title: Re: F2 citrange winter hardiness trial
Post by: hardyvermont on June 19, 2019, 04:23:50 PM
A variegated Citrange I found recently.
(https://i.postimg.cc/WhKH6Ppg/IMG-20190612-192333.jpg) (https://postimg.cc/WhKH6Ppg)

Does anyone know what causes this?  It seems to be showing up on the new growth of Poncirus crosses. 
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on June 19, 2019, 05:02:26 PM
I have additional plants with chlorotic growth. I haven't definitively determined the cause, hopefully it's nutritional rather than viral. In the worst cases apical growth is stunted and there is branching from a lower position on the stem.
(https://i.postimg.cc/06kcsdV7/yellow-1.jpg) (https://postimg.cc/06kcsdV7)

(https://i.postimg.cc/3yxC6rwB/yellow-2.jpg) (https://postimg.cc/3yxC6rwB)

Apical growth arrested, with unusual branching from a lower position.
(https://i.postimg.cc/2bqdkHhL/yellow-3.jpg) (https://postimg.cc/2bqdkHhL)

(https://i.postimg.cc/RN17ZJ6d/yellow-4.jpg) (https://postimg.cc/RN17ZJ6d)

(https://i.postimg.cc/FdJc5YXj/yellow-5.jpg) (https://postimg.cc/FdJc5YXj)

(https://i.postimg.cc/dL9CYMpS/yellow-6.jpg) (https://postimg.cc/dL9CYMpS)

(https://i.postimg.cc/HrZ7rwpw/yellow-7.jpg) (https://postimg.cc/HrZ7rwpw)
Title: Re: F2 citrange winter hardiness trial
Post by: Millet on June 19, 2019, 08:16:20 PM
It looks like just new growth.  I assume you have a nutrient plan for your trees.  The yellow should turn green as the growth matures.
Title: Re: F2 citrange winter hardiness trial
Post by: Delvi83 on June 28, 2019, 11:36:41 AM
Congratulation, it's a very good job !!!
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on July 23, 2019, 02:20:17 PM
Here are some photos from today showing the Segentrange survivors before being planted into the soil in preparation for winter. These will be slightly protected in mid-December to mid-March.

These are the hardiest survivors, many which are making good growth through the summer.
(https://i.postimg.cc/NyL7BCWc/Segentranges-July-23-2019.jpg) (https://postimg.cc/NyL7BCWc)


This plant is a monofoliate Segentrange sibling to the rest of the plants. The spines are very slender and rather long. Conestoga # 058
(https://i.postimg.cc/r07LQbLF/Monofoliate-Segentrange-July-23-2019.jpg) (https://postimg.cc/r07LQbLF)


# 010 Segentrange, one of the hardier, deciduous plants.
(https://i.postimg.cc/xkWs7Sq7/Segentrange-010-July-23-2019.jpg) (https://postimg.cc/xkWs7Sq7)


#002 Segentrange, an evergreen Segentrange showing good hardiness. This plant is not particularly thorny.
(https://i.postimg.cc/F7RB7GtT/Segentrange-002-July-23-2019.jpg) (https://postimg.cc/F7RB7GtT)


A TaiTri seedling making vigorous growth, having been planted from seed in late winter of 2019.
(https://i.postimg.cc/3y7jDJ43/Tai-Tri-July-23-2019.jpg) (https://postimg.cc/3y7jDJ43)


A Citrumelo also having been grown from seed in late winter of 2019.
(https://i.postimg.cc/XXFvtK1D/Citrumelo-July-23-2019.jpg) (https://postimg.cc/XXFvtK1D)
Title: Re: F2 citrange winter hardiness trial
Post by: mikkel on July 24, 2019, 05:31:41 AM
I might have missed a post but do you have backups of the survivours? I just wonder if these survivours are already reliable hardy enough for slightly warmer climates than yours.
I have several seedlings here to test but my ground in the field is so bad that Poncirus shows literally no growth in years. Will be the same with hybrids.
So I need to do small scale tests here in my house garden with better ground.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on July 24, 2019, 07:43:41 AM
Mikkel, I don't have backups for all the survivors at this point. I have multiple backups for the best survivors. My intention is to have a lot of flowers blooming for open cross-pollination as well as controlled pollination. The protection I reference is planting in ground, but within a structure that can be covered and insulated against record low temperatures. I find that nutritional needs are met more naturally in open soil. However, I want to maintain some control over extreme temperatures and precipitation. I selected the best drained location on the property and will begin planting very shortly, so the roots can establish before winter.

The trees won't be protected until December so the cold will remain steady until spring. In the event that there's an unusually warm period in the winter, the heat must be vented outdoors. The intent is not to provide warmth during winter, rather to protect during sub-zero temperatures.

In regards to soil fertility, this region of Pennsylvania has soils that range from mediocre to very fertile, with the limestone soils being especially fertile. The greatest challenge on my property is drainage, rather than fertility, due to the clay content in the soil.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on August 27, 2019, 08:02:26 AM
January low temperatures had no impact on the fruitfulness of Poncirus. This tree is full of fruit as usual.
(https://i.postimg.cc/1fCf9RQN/Poncirus-fruits-Aug-26-2019.jpg) (https://postimg.cc/1fCf9RQN)
Title: Re: F2 citrange winter hardiness trial
Post by: SoCal2warm on August 27, 2019, 10:19:09 AM
January low temperatures had no impact on the fruitfulness of Poncirus. This tree is full of fruit as usual.
That's very encouraging. Do they fully ripen where you are?
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on August 27, 2019, 10:43:43 AM
This is the same tree last year. The fruit ripens every year, but not before October.
(https://i.postimg.cc/njJc8tXs/IMG-20181005-072823.jpg) (https://postimg.cc/njJc8tXs)

(https://i.postimg.cc/JGP8Tk3B/IMG-20181005-072845.jpg) (https://postimg.cc/JGP8Tk3B)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on August 28, 2019, 07:28:00 PM
Many of the F2 Segentrange back ups have made good growth after being bark flap grafted onto Poncirus. These are smaller plants than the original survivors which have been field planted in preparation for winter. The plants are numbered and are labeled "Conestoga" a local river named for a Native American group that inhabited the area in the past. Early Swiss - German settlers subsequently carried the name to Ontario, Canada during the 1830's and named a river and town the same, albeit spelled the name slightly differently at times.

This scion made excellent growth in a short time.
(https://i.postimg.cc/V5ShWQwc/Scion-growth-Aug-28-2019.jpg) (https://postimg.cc/V5ShWQwc)


Conestoga #011 Deciduous
(https://i.postimg.cc/dhQmnrCT/Conestoga-011-b-Aug-28-2019.jpg) (https://postimg.cc/dhQmnrCT)


Conestoga #010 Deciduous
(https://i.postimg.cc/PpHmpDdx/Conestoga-010-Aug-28-2019.jpg) (https://postimg.cc/PpHmpDdx)


Conestoga #021
(https://i.postimg.cc/bSJSkHWz/Conestoga-021-Aug-28-2019.jpg) (https://postimg.cc/bSJSkHWz)


Conestoga #024
(https://i.postimg.cc/Q9NFZJXp/Conestoga-024-Aug-28-2019.jpg) (https://postimg.cc/Q9NFZJXp)


Conestoga #058 Monofoliate evergreen, this plant has pleasantly scented aromatic leaves when bruised.
(https://i.postimg.cc/ZWrn9Mn8/Conestoga-058-Aug-28-2019.jpg) (https://postimg.cc/ZWrn9Mn8)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on August 29, 2019, 03:38:35 AM
Nice looking plants.
Hope they will be able to harden before  frost.
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on September 13, 2019, 02:48:15 PM
2 photos of  # 011 F2 hybrid top worked on mature Poncirus trees for the upcoming winter test. This selection is one of the hardiest and multiple clones have been propagated as backups. The 3rd photo is the original survivor of these clones.
(https://i.postimg.cc/zyV67Vs7/Sept-13-2019-Conestoga-011-top-grafted.jpg) (https://postimg.cc/zyV67Vs7)

(https://i.postimg.cc/nsqdS704/Sept-13-2019-Conestoga-011-b.jpg) (https://postimg.cc/nsqdS704)


This is the original plant on May 04, 2019. This plant is deciduous and hopefully can serve as a parent in further breeding.
(https://i.postimg.cc/hJn8jY1m/May-4-2019-a.jpg) (https://postimg.cc/hJn8jY1m)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on October 13, 2019, 06:32:07 AM
The oldest Poncirus tree I have. The origin was from Major C Collins in Tifton, GA a cold hardy Citrus enthusiast. This selection has larger fruit than average and slightly more juice and pulp. Seediness is not less. The fruit size difference is not dramatic, but noticeable.


(https://i.postimg.cc/kBv7gtzF/Poncirus-October-2019b.jpg) (https://postimg.cc/kBv7gtzF)
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on October 15, 2019, 03:08:55 PM
Enclosed some actual Pictures of my Segendarin HRS899 (O or Q?) - it is surely different to poncirus - and also has some similarties - see photos enclosed. Some fruits show growths, which to my knowledge never occurs in Poncirus. The fruits also have a relatively long style and a small greenish tip, which I have observed does not occur in Poncirus fruits in this form. The smell of HRS899 fruits is a bit more pleasant than that of Poncirus fruits, and has a slight orange aroma. But look at the pictures that say more than 1000 words.

(https://i.postimg.cc/tnGkVjbx/DSC09203.jpg) (https://postimg.cc/tnGkVjbx)

(https://i.postimg.cc/8FVLHb32/DSC09208.jpg) (https://postimg.cc/8FVLHb32)

(https://i.postimg.cc/crgYGjNq/DSC09206.jpg) (https://postimg.cc/crgYGjNq)
Title: Re: F2 citrange winter hardiness trial
Post by: Bomand on October 15, 2019, 03:23:18 PM
A little diffrent from poncirus but one can see the similarities....hard to smell the picture.😁
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on October 15, 2019, 03:30:55 PM
I agree... but I could send you a fruit, then you can smell it! I don't know if sending and importing is allowed. Or someone invents (finally) I agree... but I could send you a fruit, then you can smell it! I don't know if sending and importing is allowed. Or somebody invents (finally) the transmission of smells and perhaps also of flavours - like of pictures, sounds, texts... I think he would get rich!
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on October 15, 2019, 03:38:41 PM
Great photos, do you have any photos of cut fruit? The fruit does look distinct from Poncirus. How does this tree's hardiness compare to Poncirus? I assume Poncirus has no hardiness issues in your location.

 I once transplanted a mature Poncirus tree with very pronounced nipples on the fruit. The stem end was also elongated a bit, giving a somewhat lemon-like appearance.  The tree trunk was 10 cm in diameter and did not survive transplantation. It would have been wiser to transplant a few of the small seedlings growing under the tree, or save some of the fruits.
Title: Re: F2 citrange winter hardiness trial
Post by: Bomand on October 15, 2019, 05:29:11 PM
I agree... but I could send you a fruit, then you can smell it! I don't know if sending and importing is allowed. Or someone invents (finally) I agree... but I could send you a fruit, then you can smell it! I don't know if sending and importing is allowed. Or somebody invents (finally) the transmission of smells and perhaps also of flavours - like of pictures, sounds, texts... I think he would get rich!  Yes I agree. Dont send me a fruit. I am too old to go to jail. I will just imagine😄.
Title: Re: F2 citrange winter hardiness trial
Post by: usirius on October 17, 2019, 03:35:29 AM
@Kumin:
 I cutted some years ago one and I remember they have some seeds and not much pulpe, which smelled like poncirus fruits, I did not taste them.l cut one or two after being dully ripe and droping down - I think in abut 4 weeks later. I will post phots than. Two fruits should contains seeds which are results of pollination with "Lemonade" - a sweet and very aromatic lemon like Citrus variety from New Zealand. I think the result of the hybridization will be a robust citrus hybrid with very aromatic fruits.

@Bomand:
;-)   But I don't think they'll put you in jail for a fruit. There was only once in human history a big problem because of a fruit..... that was back then in the Garden of Eden, also called Paradise!

Title: Re: F2 citrange winter hardiness trial
Post by: usirius on October 22, 2019, 02:58:22 PM
Please find my impressions and oictures from the first HRS899 seedling fruit I opened and tasted today in another thread here in the Forum:

http://tropicalfruitforum.com/index.php?topic=30863.msg369960#msg369960 (http://tropicalfruitforum.com/index.php?topic=30863.msg369960#msg369960)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 15, 2019, 12:16:13 PM
In preparation for winter, the open ground planted trees, as well as the potted trees have been enclosed in a cold frame shelter. This may not be needed in an average winter, but it provides a means for emergency protection if a 50 year Arctic cold event should occur. The very lowest temperature seen in this area in my lifetime was -24 deg F (-31.1 C) in January 1994. Such a temperature would wipe out all the pots and destroy all the other plants, at least to ground level.

This structure was hastily constructed as  we experienced a low temperature of 18 degrees (-7.77 C) earlier this week. The original plan was to cover in early December, but plans were changed due to forecasts. The plants easily coped with the 18 degrees. The plan is to protect the stems in order to  get flowering and fruiting in a few years.

There are no intentions of heating the structure, but in the event of temperatures lower than -10 deg F.(-23.3 C) it would be an option.

(https://i.postimg.cc/QH78F384/Nov-2019-cold-frame.jpg) (https://postimg.cc/QH78F384)

(https://i.postimg.cc/qN0Tg6Zq/Nov-2019-South-View.jpg) (https://postimg.cc/qN0Tg6Zq)

(https://i.postimg.cc/DWZRbrQv/Nov-2019-East-View.jpg) (https://postimg.cc/DWZRbrQv)

(https://i.postimg.cc/bSQ5j3PT/November-2019-West-View.jpg) (https://postimg.cc/bSQ5j3PT)
Title: Re: F2 citrange winter hardiness trial
Post by: Ilya11 on November 15, 2019, 01:49:50 PM
With first frost coming two out of five of my cicitrumelo seedlings (5star citrumelo pollinated by FD) are preparing to shed its leaves.

(https://d.radikal.ru/d02/1911/ac/0dc31d028a5f.jpg) (https://radikal.ru)
Title: Re: F2 citrange winter hardiness trial
Post by: kumin on November 15, 2019, 02:00:15 PM
Ilya, early dropping of leaves is a good indicator of winter preparedness. My area had warm weather until recently leaving some plants unprepared. The hardiest plants from last winter appear to be the most prepared again at this point.