Anyway, I have been growing my tomatoes under grow lights for about three to four weeks, and so far they have all done really well. However, a few days ago I noticed that what I presumed to be the first true leaves on all 12 of my plants are dying. I have already removed most of them. The one pictured below is the only one that I haven't removed yet.

I am worried that I may have early blight. There was a small circle with a darker center on one of the leaves I removed.

The soil is from Gardener's Supply company, and the plants have not been exposed to the outdoors yet

Any help/reassurance would be greatly appreciated!

I have uploaded a photo of one leaf with lighter spots, and another leaf that I already removed from one of my plants.

They are 4" cowpots. Do you think it is a nutrient issue?

kbousquet, when you say "soil," do you mean something containing actual dirt, or is it a soil-less mix of some sort? Dirt is likely to contain disease-causing organisms, which theoretically should be absent from a soil-less potting mix.

Peat pots are not conducive to keeping the growing medium at the proper level of moisture (and should be removed when planting in the ground or the final container). I don't know if cowpots are any better.

It is a mixture of mature compost, sphagnum peat, rock phosphate, gypsum, protein meal and perlite. I had extra seed starting mix, so when I repotted them two weeks ago, I just used that to fill the containers. I did not use actual dirt for any of the tomatoes.

The root stress is likely caused by several things - the pots, the mix used, the over-watering issues they cause, and the root development. If the plants can be transplanted to the garden ASAP and out of those pots and mix then they will likely recover and do fine. If not then I would suggest transplanting them ASAP into plastic containers with and sterile growing mix. Meanwhile strip off any and all affected leaves.

The damp-off symptoms in the last pic are more serious. See the constricted band around the stem of the plant right above the soil line?

Damp-off is caused by excess moisture and warm growing temps that trigger the development of the fungi in the soil. That potting mix and those pots have lots of fungi and is a good example of why using compost around seedlings isn't a good idea. It is possible to do but requires very careful monitoring of soil moisture levels and air temps to prevent problems. Something that the fiber pots - any kind - complicate.

Plants infected with damp-off have compromised circulation and rarely recover. You can try transplanting it as above and burying ALL the stem in the new soil after you remove the affected leaves and it might work. Personally I find damp-off plants not worth saving and toss them.

Next year skip the fiber pots, reduce your watering by 1/2, and use a sterile soil-less mix with no additives. The more additives the more the process is complicated and that is especially true with things such as compost and protein meal, .

Hope this helps.

Dave

Where in nature is there sterile ground?

Where do you guys get sterile mixs from? They all are so expensive! I use peat moss, next year I'll probably use peat/compost..

I think overwatering and the growers gave compost/soil a bad rap.. Where in nature do you find sterile growing conditions?

There is no sterile ground in nature but then we are growing young seedlings under artificial conditions, conditions very different than nature uses, so there is no "nature" involved. The comparison isn't valid.

Does nature grow young seedlings too? Of course but then the survival rate of seedlings in nature is less than 1:100. So if you are content with nature's survival rate, go for it.

But if the goal is maximum survival and health of the seedlings for the minimal amount of time and effort and material invested, as it is for the vast majority of growers, then do it the right way.

Basic sterile potting mixes are readily available from a huge number of sources and for very reasonable prices when compared to purchased seedlings. Given the number of healthy seedlings they provide and the returns from those seedlings the prices are minimal. It is the "fancy" non-sterile mixes with all the unneeded additives that are pricey.

Dave

I do see what you are talking about in the picture, but I cannot see it in real life. On that plant there are two marks opposite one another, but I am pretty sure that was where the cotyledons were. It almost looks like a tiny cut there. The stem immediately increases after the mark to the size above the mark. I removed the cotyledons repotting the tomatoes, but I underestimated the depth when I transplanted some of them. As a result, some of the marks were still showing.

As for watering, I water them deeply from below every three days. I had heard to water them from below until the soil was moist. Should I not wait so long? Should I only water them every 4-5 days? They were doing great before the soil became very dry a few days ago. Could that be the cause of the stress?

Thank you for your input. I am truly very new at this.

So depending on all those variables it may be daily, every other day, once a week, or whatever. Watering is done only when the plant needs it, not when we schedule it. :)

The grower has to learn to evaluate the need of the plant. You do that by

1) acknowledging that it is human nature to over-water so when in doubt - don't water, Remind yourself that the roots need to breathe even more than they need water so tell them today is breathing day.

2) accepting that plants are much more tolerant of under-watering than they are of over-watering,

3) knowing that more seedlings are killed by over-watering than by anything else

4) sticking your finger deep into the soil to check the moisture level deep down, not by surface appearance

5) bottom water - soak until the surface appears lightly damp then dump out whatever is left.

Of course all of this is moot when using fiber pots because they wick all the water out of the soil into the pot and then they dry out far too quickly. Effective watering when using them is almost impossible.

but I am pretty sure that was where the cotyledons were. It almost looks like a tiny cut there. The stem immediately increases after the mark to the size above the mark.

I disagree but only have the pics to go by. It is normal for the stem to "immediately increase after the mark" when it is damp off. In this case it is already discoloring further up the stem as well and there is interveinal discoloration on the next leaf up the stem too. But continue to monitor it. If the plant improves then I'm wrong. If it continues to fail then you will know for sure.

Fingers crossed for you. :)

Dave

The one pictured is the worst one, and there are a few more that have the same two marks on opposite sides of the stem. One of them has one mark 1/4" higher than the other one. I am sure you are right, but I am honestly hoping you are wrong. If I lose half of my plants, I will be seriously disappointed in June and July. There is always next year, I guess.