Tomato seedlings dying off

[Kurt]

Some images of what the roots need.

https://www.google.com/search?q=tomato+ ... e&ie=UTF-8

[JimmyNardello]

While I don't think you're dealing with damping off, either, it's important to know that damping off isn't caused by only one kind of pathogen. So, it's not always the same in the way it manifests. For instance, if Verticillium is causing damping off, it's probably going to look a lot different than if Pythium is causing it. I don't think Verticillium would attack the base of the stem (it's a vascular disease that can make the whole plant wilt; also, it can affect the leaf edges, too, making them yellow in parts, without causing wilt).

Here are some possibilities:
- Mites
- Herbicide in your soil/water
- Disease (although I don't think it's damping off, I still think Verticillium is a possibility here; it can make young plants look scorched, and it makes them more prone to drought damage; if Verticillium is the case, then fertilizer would probably actually help rather than hurt; Verticillium prevents plants from getting needed nutrients, and fertilization is one of the primary ways to combat it if you're not going to pull up the plant; it's most effective on plants that only have foliar symptoms, however; if they have stem wilting symptoms, you should probably pull them up; Verticillium has a complicated life-cycle, and it can be a problem at all levels of moisture, while seeming to respond to changes in it at the same time; other diseases are possible, even viruses).
- Less than ideal soil

Maybe try watering with filtered or borrowed water, and see what happens. Getting your water tested is something I would recommend.

Very compelling answers, and I'm aware of the different pathogens that cause damping off - I use this as a blanket term. I'm less aware of how these other pathogens manifest in the plant, so I'll be looking more into that when I have time.

Outside of getting my water tested (the most recent water report from my city that I can find is from 2021) I have a feeling it's the amount of water my mix holds. I may try and start some radishes to see the difference between bottom watering, watering from above (with tap water), and then attempting this with filtered water.

The reason I suspect the mix is because I haven't watered my peppers or the remaining tomatoes in several days, and while the soil looks dry, I believe it's still holding onto a good amount of water. The peppers are incredibly healthy right now, and the remaining tomatoes (which, ironically, are some of the same tomatoes that survived last year - including a Black from Tula & Crimson that grew from seeds I saved.) Even when I dig down, the soil physically feels dry, but I can sort of tell it's still holding moisture. I've always shrugged this off and thought, "OK. Time to water." But I suspect doing this several times over has led to deceivingly soggy soil. As mentioned above, both of the mixes I used are peat-based, so this would make sense. I also added probably less perlite than I should have.

The only way I can feasibly address the mix is to A) take the cells outside and put them in the greenhouse where they'll dry far too quickly for any excess moisture to take hold, or B) change out the starting mix & start over (expensive). I'd rather go with option A once I set everything up in the greenhouse.

The sun seems to solve 90% of these issues for me. I don't think I've had problems starting more cold-hardy seedlings outside, ever.

[MissS]

The most reliable way that I know of to know when to water is to go by weight. I tell people to keep a full unplanted, unwatered cell pack to use as a comparison. Then lift the seedlings and see if they are as light as the unwatered cell pack. If they are close then it is time to water. If they feel heavier, then leave them be.

Perhaps the next time that you use the seed mix, add more perlite to the mix.

I do agree that the sun works miracles for our plants.

[JimmyNardello]

The most reliable way that I know of to know when to water is to go by weight. I tell people to keep a full unplanted, unwatered cell pack to use as a comparison. Then lift the seedlings and see if they are as light as the unwatered cell pack. If they are close then it is time to water. If they feel heavier, then leave them be.

Perhaps the next time that you use the seed mix, add more perlite to the mix.

I do agree that the sun works miracles for our plants.

I'll definitely be doing this the next time I make my own mix.

And about the sun, absolutely. I started some chamomile, lettuces & other things in the greenhouse w/o heating set up. The lettuce is huge, the chamomile germinated in a day, and the rest of the seedlings are doing really well. Most of the seedlings are actually native plants I'm trying to get an early start on - most take a LONG time to germinate - and they're popping up like crazy. The only problem I've had is a little bit of algae growing on top of some of the cells.

[JimmyNardello]

UPDATE!

Just wanted to post an update on my tomato situation. To sum it all up, pretty much everything changed the moment I made the decision to move my surviving seedlings into the greenhouse. This picture illustrates this best.

I changed virtually nothing about my watering practices & started new seedlings that thrived from the beginning. Crazy how many problems are solved by simply the presence of sunlight & open air.



I also discovered something interesting early on. A couple seedlings I had started in the greenhouse were mysteriously topped as they came up, so I immediately assumed this was due to pest pressure. However, the more I looked into it, I realized that it was actually the seed essentially catching the seed leaves & decapitating the seedling. Seedlings that survived this had some sort of bruising on their outer tips.

It also seems like this was what was causing the tips of the leaves in some of the pictures I posted earlier to become chipped off. This issue occurred in several different tomato varieties. Has anyone else experienced this?

[JRinPA]

If corn tips gets yellow, it is fertilizer burn for me. Too much nitrogen too close, and too little rain and warmth to utilize it.

[MissS]

Yes. When the seed head will not release from the new plant, it's referred to as a helmet head. If it does not come off it can be fatal to the new seedling. To prevent this I plant my seeds 1/4" deep. I find the shallower I plant, the more helmet heads I have. The friction with the soil seems to help remove the seed capsule. You can also help the plant to remove it by keeping the seed head moist which softens the shell. I will often moisten the seed with some saliva. Wait a few minutes. Apply more saliva and then ever so gently try to pull it off. If it does not move then leave it sit so that you don't break the plant off and then come back and try again later.

[bower]

As Patti said, a very common problem for tomato seeds.
Factors include: age of seed or dryness of seed lot; humidity at germination; planting depth and soil texture; seedling vigor or growth rate, in part dependent on temperature. Mine do best on a heat mat because of the cool environment - this gives them a fast enough emergence to push off the seed coat. Covered with 3-5 mm soil, enough for them to push against and pull away from the seed coat. Also I keep them in a clamshell so the humidity is quite high, to keep the seed coat moist and soft until it has been shucked.
These tweaks help, but there are still some cases where the coat isn't completely shucked, or seed lots that have more trouble.
If the exposed cotyledons have dead bits on the end, as in one of your pics, nip off the bad bits to give the seedling best chance to develop.
I'm glad to hear your second round in the greenhouse did so much better.