The Tropical Fruit Forum

Widespread outside cultivation happens just in zone 9b, you can find folks that grows them outside in zone 9a in good/sheltered spots, but the plants are going to die eventually. Regarding the zone 8, there are basically no plants outside in winter, people grow them in pot and bring them inside. To be fair, most of the historical collection in central italy were grown in pot just because of that, rich people moved lemon in building made exactly for this reason called limonaie, and there they were kept and they could be also heated when needed.
There is an interesting exception to that. Well, the lemons weren't exceptionally cold hardy, but the place is microclimatically interesting: and those are the glacial lakes in nothern Italy, where in a couple of place they grew lemons due the warmer enviroment due the presence of the lake.
I wonder what kind of madman saw a glacial lake and said "i'm going to grow lemons here" but it did work!
I have been there last autumn. Keep in mind that place is 40 miles from Switzerland.  This is the landscape:





Amazing micro/nanoclimate in my opinion.
There's also a place there called "Limone sul garda" ( https://it.wikipedia.org/wiki/Limone_sul_Garda )which sounds pretty much like "Lemon over the Garda lake" wich coincidentally has a widespread lemon cultivation. Such structure you see in the pics were used to put some trellis on lemons in order to defend them by light frosts in windless nights. If i were to search for an hardy lemon that is a good place to start, i guess, even if i don't know how much of the original clones may be still alive there. AFAIK no especially hardy lemon is widely grown in italy.
USDA zones are not so good for evaluating italian climate because i'm under the impression that our winter days are darker and cooler compared to same USDA zone of the east coast, and our spring/autumn are longer and also on average cooler (in same usda zones i mean). 

Quote from: Pancrazio on May 22, 2019, 07:21:22 PM

I can't tell for any nursery in EU but i know for a fact that our phytosanitary service routinely inspect citrus nurseries for CTV, so if someone has it in catalogue, they should have been tested.

I do not think so.
https://corvigo.blogspot.com/2019/05/e-il-virus-della-tristeza-va-avanti.html?fbclid=IwAR1uSxI06sLQhL_vZbku8Ky0TD52nk-i60HlW9BvoBEslr1YigxYxEiC47E

I know it's hard to believe from outside, but what happens in Sicily (or southern italy) doesn't necessarily reflect the situation in Italy as whole (or in Tuscany for that matter). Moreso since our phytosanitary legislation has become a local matter; a senseless decision, which has created enormous damages (I think to xylella infection), but this how it works here now.

Quote from: Pancrazio on May 22, 2019, 07:21:22 PM

BTW, speaking of seeds, does anyone knows if in europe there's any kind of seedless yuzu?

In some private collections in France and Belgium, but there is a problem with CTV.

Oh. Too bad.

But as far as I know sudachi and yuko are not worth to grow for fruit, only as curiosity.

Hey Radoslav, care to elaborate? Are they insipid/wortless for lack of juice, and/or unpalatable?

Not sure why. What i know is that some guy on the Italian forum attempted to get this one and got declined. Either they had a minimum order unapproachable (like, say, 100 plants) or they don' seel directly to private custumers. If you are interested i may ask.

Lemox is patented, and apparently they don't sell to the public.

Interesting! I have a 1-year old valentine in the ground and just grafted cocktail, but not on the same tree... -8C is possible here, but very uncommon, I hope the trees grow big before that happens, if it does.
What frost cover do you use, is that spun polyester or plastic? I can't quite tell from the photo. Also, I wonder whether it would help to keep it a little away from the plant?

Spun polyester! It is cheap and id doesn't has the dowsides of plastic which doesn't really allows air circulation.

I did some measurements with a medium-weight spun poly floating row cover draped over a small banana. The result was the same inside temperature as outside, but those measurements were above freezing. On their own these covers do not increase the minimum temperature.

In my understanding they just avoid (reduce) radiative cooling. That sort of cooling that happens when a flat surface is exposed towards the dark cloudless night sky and the entire infrared radiation of the object doesn't get replenished by radiative heating from sun and atmosphere. In this case, flat surfaces exposed towards the sky gets cooler than air (that's the reason why on nights around 32°F you can see cars with frozen roofs even if temperature never got under 32). Covering the plant, you reflect back to the plant part of the infrared radiation, thus keeping the plant at the same temperature of the air, and in several cases this is a net gain.
They are less useful instead in cloudy nights (which incidentally are also warmer on average because of said effect, cloud behave like a giant blanket).

I'm assuming that's in climate zone 8b. Citrus fruits have long been grown in Italy (with some difficultly in Italy's North).
I don't think pomelos would ever survive outside like that in my zone 8a Pacific Northwest climate. My Bloomsweet barely survived (with a cover, in a warm spot up against the south-facing side of the house) and right now it looks like it could go either way, I wouldn't be surprised if it dies. (Although temperatures have warmed up by now so any damage should have fully manifested itself by now, I would think)

Oh. USDA climate zone shouldn't be taken seriously in consideration when describing european climate. Sure, the mathematical calculation still works and as general rule, you can get an idea of what kind of winter you can expect, but they are aimed to tie a plant to a particular climate and as general rule they fail in taking in account the effect of consistent low temperature on some tropical and subtropical plant. This has been a major topic of people on italian forums. I think is important to point this!
Over the years i have found pretty big discrepancies from what you people from US tell us about citrus and when i see from other italian members.Because of that i calculate a usda map zone for italy based on several weather stations, and as you can see i'm between zone 9a and 8b (Florence).

However a lot of the stuff people says it works for usda zone 9a at my place doesn't grow. Like bananas: i have been growing bananas for quite some times and attempted them in ground for several winter but more often than not they die to the corm (dwarf namwah).

Besides, I'm a little bit further North of you, about the same latitude as Northern France.
I'm not that surprised that pomelos could manage to survive in Florence, Italy with a cover over them.
The fact that you appear to be in the middle of a city and they are up against a fence probably helps as well. That fence acts like a windbreak. The concrete bottom of that fence probably helps store a little heat too.

Well, keep in mind that the citrus growing zone in Italy starts around naples, and in Tuscany there isn't even a single plantation of citrus. Definitively citrus has been grown historically all over Italy but northern than Rome, it took quite some effort,and it was reserved to nobles who could afford to heat them in winter in ages when common folk had to endure the frost. Definitively in some places of Italy citrus aren't at home.

I'm thinking to drop few lines about an experience i made last winter regarding those two plants.
Is hard to fine accurate comparision between two clones because one never knows how they were spaced and especially how much their rootstock/nutrition can vary.
Well, in my case, i guess, i have kept as close as possible two varieties in rigorously the same environment.
I grated both valentine and coctail on same rootstock, at the same height in the same spot, so everithing they got was rigorously equal. Just... i'm not sure what rootstock it is since i reused a failed clementine which i'm not sure about the origin, but i guess it must be citrumelo.



They grew nicely during summer then winter hit.



In the first column you have the average temperature in celsius and in the second the minimum temperature in celsius. As you can see we got till 17F with about two weeks of sub freezing nights (and i mean, not just light frosts).
During all this time both the valentine and the cocktail were outside with just a light frost cloth.
Well somehow they manage to survive with just little dieback and not becoming completely defoliated. No flowering this year but they bounced back.

Here a picture of them just after the frost at the end of january (the right part of the plant is cocktail and the left part is valentine, frost cloth moved up to show leaf damage):



They managed to survive! Pretty beaten but alive. Of course some degree of defoliation was to be expected and so happened (BTW you can see on right bottom corner of the pic a twig of ilya11's voss bloomsweet grapefruit completely unfazed by the cold)
This is them a month later:



The cocktail grapefruit got beaten a little harden than Valentine, even if i have to admit that on a small sized plant like this one is hard to make conclusive statements.
What can be said is that Valentine and Cocktail when dormant are pretty cold tolerant. Also im not completely sure but i suspect that keeping some leaves alive on more exposed twigs may be useful to help the plant in avoiding entire twig dieback. It's just a thought though.
Right now coctail has also a flower while valentine is a little more shy, but they completely recovered.

Also Agrumi Lenzi, ships outside italy, i'm unsure if outside EU, but i think yes.
https://agrumilenzi.it/

Funny thing is, that place is about 200m away from my work place. Adriano, if you need hints on the opening days drop me a line, in fact the villa isn't opened every day of the year. So be sure to check in advance.

Pancrazio, I have a 25ft Mexicola in my front yard. If you would like seeds from the tree mailed to you i could do that...unfortunately it ripens in November or so. You could get my seeds and overwinter them in tall grow pots and plant them in the Spring. Hit me up if you would like some. My tree is near a busy sidewalk and is usually picked clean of any low hanging fruit, so I would have to get the fruit picker out. Chris

Thank you very much for your kind offer. This forum always prove itself filled with helpful people.

That's a letter showing what was packed.  Dr. Mary Lou Arpaia is a world class U.C.R. fruit developer with a specialty in avocados, breeding for improved varieties.  She is in charge of the extensive U. of California avocado museum or collection along with her curator Julie Frink.  She works with commercial farms across the world like S. Africa, Australia, Israel, etc.  She may be a good source for connections in Spain or may be able to mail you scions.  Kicker is postage.  I hit the ceiling when by surprise they mailed me an overnight FedX package of scions at a cost of near $100 U.S.D.  Shipping is gonna be a stickler, scions are free.

Thank you very much, I'll try to write her. Firstly, I will ask to my local university if they may be interested in backing me up. Maybe with some official role the chance for a positive answer will increase. Yes, i know that shipping overseas, can get pretty expensive especially if done as express package. I won't forget when some years ago i have been asked for 600€ for the shipping of 4 plants (i didn't bought them BTW  ). Well i guess that fruit growing is a pretty cheap hobby but it has its expensive moments.

Pancrazio did you check Viveros Blanco in Spain?

http://www.viverosblanco.com/it/portainnesto

Thank you for your suggestion Jose. Yes, of course i tried. As I tried with Canarius, Aguacate vivai, Frutales tropicale, pepiniere du bosc, and so on. Well, the fact that they don't ship is a big issue, as you imagine since they are thousands of km from me. But even if they are able to ship i won't place an order because as you see and it's clearly stated in their page that they mexicola plants are seed grown. They aren't Mexicola; they are, at best Mexicola's seedlings. But here's the catch: I suspect that by the term "mexicola" they refer just to a mexican race avocado. I talked about that with Solko in one of my previous attempt to locate a source for that plant in the eu and we both agreed on that. So at this point before doing a big effort to get a plant from spain and not being sure that it is actually a mixicola, i prefer to do a relatively smaller effort and try to get a plant for US and be actually sure of its cultivar.
After that hopefully i can become a source of scions for people in the eu.

This is very interesting. Everywhere i have read that such grapefruit was way more tender, but it looks like it is on par with oranges. Since The fruits are already very good in november, at least at mu place, it proves a fine addition to my plants!

Hi everyone.
As usual, in this time of the year i look for the new planting for my garden. Avocado is my objective now.
As much i have been searching in Europe, i haven't been able to find a genuine Mexicola avocado. Part of the problem is that for some mistake, in Europe "Mexicola" is used as the generic name of mexican race avocado, so I get several nurseries that sell mexicola avocados but often they reveals themselves to be just seed grown mexican race avocados. But i want a true, grafted, mexicola avocado.
So, it there anyone here knowing about a nursery selling the true grafted Mexicola avocado, and willing to ship oversea with the necessary documentation?
It's a long shot, i know, but for real, i have been searching for that plant for the last 6-8 years.
Thank you.

Does this happens on new leaves or just on older leaves? I'm asking because this is remarkably similar to my spring leaf loss. Older leaves just turn yellow, show sign of necrosis (black spot) and detach. I think this is part of the normal cycling of leaves, if that's is the case.
If this happens on newer leaves i would be more worried. I that case i would probably go with copper too.