Author Topic: Alternaria and chlorosis  (Read 716 times)

hardyvermont

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Alternaria and chlorosis
« on: January 28, 2022, 12:42:30 AM »
Assuming this is the cause of albino seedlings

https://pubmed.ncbi.nlm.nih.gov/17817394/

Would fungicide help?
« Last Edit: January 28, 2022, 12:53:13 AM by hardyvermont »

kumin

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Re: Alternaria and chlorosis
« Reply #1 on: January 28, 2022, 02:06:31 AM »
In commercial production rootstock seeds are routinely subjected to hot water and fungicide treatments. Additionally, removing the testa is said to be preventative.
I've successfully treated surface mold by briefly soaking the seeds in a sodium hypochlorite solution, removing the testa, again soaking in a hypochlorite solution, then rinsing repeatedly with distilled water. None of the small batch of seeds developed seedling albinism.
« Last Edit: January 28, 2022, 05:15:39 AM by kumin »

Walt

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Re: Alternaria and chlorosis
« Reply #2 on: January 28, 2022, 03:41:12 PM »
Good information.  But what concentration sodium  hypochlorite hypochlorite and how long?  And how hot is the water and how long?
I've been using hydrogen peroxide this year with good success.  I used 3% or whatever comes in the bottle at Walmart.  I think it is 3%.  I would put seeds in it and let it stand for a few hours.   

It was only last year that I  learned that the albinism is caused by a pathogen.  I used to breed beans and sorghum.  With Sorghum bicolor x S.  halepense and Phaesiolus vulgarus x Ph. coccineus hybrids, albinos would segregate out for several generations.  I thought I was getting the same thing in interspecific hybrids.  But with the treatment there have been no albinos.

kumin

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Re: Alternaria and chlorosis
« Reply #3 on: January 28, 2022, 04:33:34 PM »
Here are a few links regarding Citrus seed sterilization.

https://edis.ifas.ufl.edu/pdf%5CHS%5CHS130900.pdf

 and https://fruitmentor.com/growing-citrus-trees-from-seed

Hydrogen peroxide may be a good alternative.

pagnr

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Re: Alternaria and chlorosis
« Reply #4 on: January 29, 2022, 08:18:39 AM »
Auscitrus  rootstock seed info..
"seed is heat treated at 52 degrees C for 10 minutes and surface sterilised with chlorine before being dried
then treated with Thiram fungicide for cool storage"

As far as I know, Thiram is applied for seed storage and germination protection.
Alternaria is listed as one of the pathogens it is used against.
https://www.cropscience.bayer.us/seedgrowth/thiram/pest
Thiram is not used on all Fungi / pathogen problems. Pythium doesn't seem to be listed ??
Similarly other Fungicides would not be effective against Alternaria.

Good hygiene is also important in seed collection, such as picking fruit before it falls to ground, extracting seed before fruit goes off.
Cleaning seed thoroughly of juice and pulp etc, using new zip bags for seed, sterilising tools and strainers with boiling water between seed types/lots.
Working in a clean area, i.e. kitchen when wife not home !!!
Cleaning your hands between seed lots.
Cleaning/sterilizing the the peel of any older, fallen, mouldy fruit etc before getting to the seeds.

Soilless propagation mixes should reduce pathogens, as should heat treating the mix components ( usually not with fertiliser added ).
Heat could be steam, boiling, solarisation.


Walt

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Re: Alternaria and chlorosis
« Reply #5 on: January 29, 2022, 03:32:53 PM »
I have learned a lot here.  Thanks to all who posted.
I got by without this information, but with only 80%-90% success.  This year, knowing that the albinism was due to fungus, which I learned from this forum after last year's planting, I got much better results.  I hope to have even fewer losses next year.

hardyvermont

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Re: Alternaria and chlorosis
« Reply #6 on: January 30, 2022, 12:51:20 AM »

pagnr

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Re: Alternaria and chlorosis
« Reply #7 on: January 30, 2022, 04:30:55 AM »
I have received some commercial seed treated as follows. These were excellent quality seed.

"To reduce the risk of Phytophthora spp. our seeds are heat treated at 127 F for 10 minutes. The seeds are then treated with a 1% solution of 8-hydroxyquinoline sulfate to reduce the occurrence of molds and improve storage life. The treated seed is stored in poly bags at 35 F to 45 F and regularly inspected for mold or fungus."

Also have got seed sample treated with Laboratory surface sterilant, probably (Hexol or similar I think ? ). These too gave excellent germination.

Personally I find Thiram treated seed Citrus hard to work with.

This year for Citrus I simply used the gel based hand sanitiser we are all now familiar with. 5 to 10 mins in the gel then rinse thoroughly before storage in bags.
Overall pretty good germination.

poncirsguy

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Re: Alternaria and chlorosis
« Reply #8 on: January 30, 2022, 09:58:46 AM »
I plant my seeds as they are and let the strongest grow and the inferior seeds sprout and die.  This insures that I only have superior trees.

pagnr

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Re: Alternaria and chlorosis
« Reply #9 on: January 31, 2022, 03:54:13 PM »
I plant my seeds as they are and let the strongest grow and the inferior seeds sprout and die.  This insures that I only have superior trees.

Sounds like an ok strategy for rootstocks and strictly nuclear types.
It's interesting that in a pot of seedlings, some will be white (Alternaria and chlorosis, or another mutation ??? ), and others seem unaffected.
Are the normal plants more resistant to infection or just lucky ??

On the other hand I have a few interesting off types that had to be helped to get going, some now survive as grafted only.
Off types can be weaker, have interesting characters and flower early.

kumin

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Re: Alternaria and chlorosis
« Reply #10 on: February 03, 2022, 11:57:27 AM »
Although not specific to Citrus germination, this link addresses a number of contributing factors involved in damping off causes.

https://www.youtube.com/watch?v=K7HAyNG_FSY

pagnr

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Re: Alternaria and chlorosis
« Reply #11 on: February 08, 2022, 04:13:17 PM »
I was once contacted by a Citrus breeding team in Australia, to supply a sample of fresh extracted rootstock seed.
They could not find any Pythium free seed from Thiram treated seed.

 

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