Are these cotyledon spots normal?

[JoeP]

Can someone tell me if the black spots on the yellowing cotyledons are normal?

Last year was my first time starting from seed. I know that after a set or two of true leaves the cotyledon’s will yellow and eventually fall off but I don’t remember if the black spots are normal.

I may be guilty of overwatering. I was watering with a spray bottle every other day when the top of the seed starting medium appeared dry. They are inside, under lights, and the temp fluctuates between 63 and 72 degrees. They have not yet been exposed to direct sunlight. I did have one corner of the flat on a heat mat to germinate pepper seeds. I used the heat mat to germinate the tomatoes too but removed it once they sprouted.

Thanks,
JoeP

[bower]

That doesn't look good or normal to me, it looks like disease I have seen. I would remove them pre-emptively, don't wait for them to drop, and burn em, don't compost. This kind of thing, I believe, gets in the soil and lingers, and treats plants really badly if it's cold and wet.

[JoeP]

Originally Posted by bower

That doesn't look good or normal to me, it looks like disease I have seen. I would remove them pre-emptively, don't wait for them to drop, and burn em, don't compost. This kind of thing, I believe, gets in the soil and lingers, and treats plants really badly if it's cold and wet.

By remove "them" do you mean the (1) just the affected cotyledons, (2) the entire seedling with affected cotyledons, or (3) the whole cell where these affected plants are?

Thanks,

[mcsee]

Looks more like water damage to me. Before you pull any, wait until others comment first.

[bower]

I would pinch off the affected cotyledons, and keep watch on the seedlings to remove affected leaves if it begins to spread. I would not cull the plant unless it is really going under, but I would keep affected plants away from healthy seedlings.

I would give the affected seedlings some TLC as well after removing leaves, like kelp solution in their watering because it toughens them against stress, and willow water or dissolved ASA would also help to boost their immune response.

I don't use foliar sprays or feedings myself, because we have such a moist climate, and any wetting of the leaves seems to make the plants susceptible. So I would water them very carefully not to splash the leaves. Also I would make sure they have a chance for the soil to dry out, since I think this is a fungal disease that lurks on the soil surface. Maybe mulching with something antifungal, like cedar shavings, would help?

Those are my impressions, but maybe a plant pathologist is lurking here who can name the pathogen and give you more specific advice!

[carolyn137]

Yes, I've seen the black spots from time to time and I just ignore it.

Remember that cotyledons are not true leaves so they don't have the attchment sites on the upper leaf surface for the common tomato foliage diseases/

More likely it's a combination of too moist conditions which allows for growth of normal fungi in the environment to land on them and I don't see it as a serious problem.

For any of you who do fermentations you've seen the black fungi in the mat that covers the surface, or just look at an old decaying orange and you can see the same on the surface along with green fungal colonies and other colored ones as well.

The most common normal black fungus genus is Aspergillus, there are many species and what you see are the condia.

So no threat of a tomato disease and as has been said above, the cotyledons fall off anyway.

[JoeP]

Originally Posted by carolyn137

Yes, I've seen the black spots from time to time and I just ignore it.

Remember that cotyledons are not true leaves so they don't have the attchment sites on the upper leaf surface for the common tomato foliage diseases/

More likely it's a combination of too moist conditions which allows for growth of normal fungi in the environment to land on them and I don't see it as a serious problem.

For any of you who do fermentations you've seen the black fungi in the mat that covers the surface, or just look at an old decaying orange and you can see the same on the surface along with green fungal colonies and other colored ones as well.

The most common normal black fungus genus is Aspergillus, there are many species and what you see are the condia.

So no threat of a tomato disease and as has been said above, the cotyledons fall off anyway.

Whew! Thank you, Carolyn. I tend to panic at the first sight of trouble.