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Old April 15, 2018   #1
roper2008
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Default Grey mold question

If I saved seeds from a tomato plant that had grey mold, would it transfer to the
seeds?
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Old 4 Weeks Ago   #2
KarenO
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Potentially yes.
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Old 4 Weeks Ago   #3
b54red
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I think that Carol might be the best person to answer the question of whether it can be seed born. I do know that I usually have some or most of my black varieties get gray mold to some degree or another most years but not always. When we have had very low humidity like we did one or two years gray mold doesn't appear much or at all. Of course that is a rare thing down here so most years we are dealing with humidity hovering near 100% much of the time and that means damp leaves and that seems to increase the chances of gray mold along with almost every other foliage disease.

I am not certain how gray mold gets started but I usually have several plantings of the same varieties spaced out in the garden and some get gray mold and some don't. They all come from the same saved seeds. I ferment my seeds and treat them with a bleach solution for a bit before drying them and storing them.

One thing I have noticed over the years of dealing with gray mold is that if it is allowed to linger on a plant without treatment to stop it then the gray mold seems to become systemic at which point it also affects the fruit and can't be controlled or stopped. It seems to me that once it gets to this stage of infestation that it is best to pull the plant as treatment with bleach or copper does little to slow it down. Since I am no scientist or biologist I have only my own observations to go on. I have been dealing with this problem for years with black tomato varieties and sometimes GWR varieties and I have found that use of a copper fungicide will control or stop gray mold most of the time in normal years but in times when conditions favor gray mold development a diluted bleach spray is very helpful in stopping it if used early enough in the infection. It is also most helpful to have plants that are pruned to maintain good air flow and good light penetration. Dense foliage seems to be a recipe for gray mold when conditions are favorable for it.

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Old 4 Weeks Ago   #4
bower
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Grey mold doesn't dwell inside the seed coat, so in that sense it is not "seed borne". Fermentation and other seed processing treatments should remove it from the seed coat, but IMO the spores are in the environment anyway, being not specific to tomatoes but very much activated by the conditions that they require in season. I have never seen grey mold on a seedling, maybe for two reasons: (1) the environment in spring is less conducive to the mold, and (2) the seedlings have a healthy "immune" status, and beneficial microbial community outweighs any stray spore that may have landed on the seeds. And a third reason might be (3) grey mold colonizes aerial parts of the plant so a seed planted in the earth and sprouting roots is not in the favorable environment for the mold to develop.

I think if you took a seed and actually rolled it in dried up moldy tomato parts, you might have different results, just because the nasty spores would outnumber the beneficials.

Since grey mold doesn't live inside the seed coat, the best way to prevent any possibility of transmission via seeds would be to bleach treat them just prior to sowing. I believe it does reduce germination by a small percent, but is practiced by many growers, to remove all surface pathogens from seeds at planting time.

OTOH, rereading your question, I would not recommend saving seeds from fruit affected by grey mold.

Last edited by bower; 4 Weeks Ago at 07:48 AM. Reason: add
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Old 4 Weeks Ago   #5
roper2008
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Thank you, I did ferment the seeds, but I wasn’t completely comfortable using them this year.
It is a black variety. I don’t think I will use them.

Bill, I thought I didn’t start any black varieties, but I forgot about my 2 Carbon seedlings. I was
so looking forward to trying it because of all the good reviews. I’m going to still grow them, and
try your treatments as soon as I see the grey mold.

What’s weird about this grey mold is that it started about 3 years ago. It’s always been humid
here. I’ve grown blacks before without any grey mold (black Krim, Indian Stripe, etc) I will also
keep them away from my other tomato plants.

Last edited by roper2008; 4 Weeks Ago at 07:16 AM.
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Old 4 Weeks Ago   #6
b54red
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Quote:
Originally Posted by roper2008 View Post
Thank you, I did ferment the seeds, but I wasn’t completely comfortable using them this year.
It is a black variety. I don’t think I will use them.

Bill, I thought I didn’t start any black varieties, but I forgot about my 2 Carbon seedlings. I was
so looking forward to trying it because of all the good reviews. I’m going to still grow them, and
try your treatments as soon as I see the grey mold.

What’s weird about this grey mold is that it started about 3 years ago. It’s always been humid
here. I’ve grown blacks before without any grey mold (black Krim, Indian Stripe, etc) I will also
keep them away from my other tomato plants.
The very first time I grew a few black tomatoes I got gray mold on some of them and initially had no idea what I was dealing with or how to treat it. Some years it is not a problem and some years it is. I don't believe it is seed born due to the fact that it seems to be a problem more of the weather conditions and plant crowding. Regular spraying with a copper fungicide is usually adequate to keep gray mold at bay but in wet times and the cool nights of fall when it is damp I have to use the diluted bleach spray to keep it under control.

Do not wait to use the bleach spray once you see gray mold appear but rather treat it as quickly and often as necessary to get rid of it as fast as you can to prevent it spreading. The next day or day after treatment with the bleach spray remove the shriveled stems and leaves and spray with a copper spray. It is frequently necessary to spray with the bleach spray twice or more in a short time in order to get good results but delaying for even a few days in treating the problem will frequently result in too much foliage lose due to the rapidity with which it can spread if the conditions are favorable. Usually if the humidity isn't too high and the plants are kept well pruned and sprayed with a copper spray gray mold is just a minor or even no problem; but during times of frequent rain and or excessive humidity it can be a challenge to control.

Despite gray molds frequent appearance on some of the black varieties and sometimes the GWR varieties I wouldn't dream of not planting them. I have only rarely seen it spread to other types of tomatoes and that was always due to me not maintaining the plants properly or maintaining my fungicide spraying. Some of my black tomato varieties are frequently among my top producers despite even a bad year for gray mold and in years when it is not a problem they are almost always the top producers in the heat of summer and early fall.

Bill
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