Tomatoes/peppers wilting: too much rain or missing nutrients

[St. Louis gardener]

I posted this on another thread about rain, but no one's responded, so maybe I'll have better luck here. My tomato and sweet pepper plants have been turning yellow and wilting. How can I tell if this is from too much rain or lack of nutrients? The ground has been "wet" ever since we planted in late April. The only other veggies not from seed are the squash, which are doing well. They are in a different part of the garden but all the soil is the same pH (neutral) and prepared and fertilized the same way. Another weird thing is that even though the tomato/pepper leaves (especially the lower ones) are yellowish and some of them are curling, and the whole plant looks less robust (a lighter shade of green, thinner, etc.) than when we planted them, every single one is bearing fruit! The plants are a foot or so high, yet I picked my first ripe cherry tomatoes today. What's up with that? Are all the nutrients going to produce fruit and none left for the plant itself? If they need more fertilizer, how do I feed them without adding more water to the already saturated soil? Will spraying the leaves with compost tea help?

[jal_ut]

I would not add fertilizer. I would have patience. You will get some warm sunny weather one day soon and they will have a turn around.
I assume these are nursery plants? It is a common thing for the leaves the plants have when planted out to turn yellow. It is no reflection on the soil but has more to do with the stronger light and the leaves yellow and curl up. The new growth usually has a good color.

[garden5]

That's a tough one to call. I'd have to say that if your garden is fertilized and your ph is where it should be, then it's probably your water situation.

However, what has the temperature been like for you? Have there been extremes of heat?

[St. Louis gardener]

The temps here have consistently been in the 80s and low 90s for a few weeks. Before that we had some cooler periods where at night it would drop down into the 40s, but that has not happened for a while now. I use weed barrier and wood chips mulch, both of which are designed to keep in heat and moisture, which, under normal summer conditions in St. Louis, is a good thing. But I guess it didn't work in my favor this year. I just checked the moisture levels again, and they still register "wet" even though we haven't had any rain for about 24 hours. Guess it will take a lot longer than that for the ground to dry out. But I am noticing some top leaves of some of the tomatoes getting greener and looking healthier in the last couple of days. The pepper plants are another story. They really look sick, with very light green to yellowish leaves that curl inward. Not sure if they are going to make it. How long do I wait before I give up on them? Patience is not my strong suit. LOL

[garden5]

The wood chips may be robbing your soil of nitrogen as they are breaking down and the prolonged extreme temps may not be helping, either (though pepper so appreciate a little hot weather). Perhaps replace the wood chip mulch with some hay or grass clippings and give the plants a little fish-emulsion?

[St. Louis gardener]

The wood chips are on top of the black plastic weed barrier. I planted the peppers and tomatoes on April 22 and by May 11 (maybe sooner), they were wilting and yellowing. Could wood chips break down through a weed barrier and rob the soil of nitrogen that fast?

[garden5]

It sounds like you're fine with the wood chips then. Could it be that the plastic is keeping your soil from drying out?

If the moist soil is the problem, I'd have to agree with Jal and just say that patience is going to be your best bet. Wait it out and see what happens.

Good luck.

[St. Louis gardener]

We've just had 3 days in a row without much rain (< .25 in. yesterday) and the tomatoes are perking up. If they continue to do so, they might make it. On the other hand, the peppers are still looking bad. A couple of days ago I thought I saw some new, darker green growth at the tops, but this morning I checked and the leaves that were yellow fell off overnight (or during the rainstorm) Can sweet pepper plants survive with just a few green leaves at the top? How fast should they be growing? I don't think they've grown more than 4 inches since I planted them April 22. If we don't get much rain this coming week, I may feed them and see what happens.

[cynthia_h]

More information, please, on this "black weed barrier."

If it's plastic sheeting, the soil is being partially solarized (heated) and may be too hot for the roots of these plants.

Also, there may not be enough of an air exchange, especially given the extended rains in your region this season, to keep the roots healthy. Roots need air just as much as leaves do. Weed barriers, whether plastic or "geotextile," work on the principle of denying air and sun to the soil in order to keep weeds from growing through.

Side note from working in my MIL's yard: once weeds *do* grow through this stuff, esp. the geotextile kind, pulling the weeds up is a real pain in the patootie. You end up pulling the weed plus about 3 sq. ft. of weed block, stretching the "approved" holes, where your other hand reaches underneath to get the rest of the weed, etc. I'm just about ready to start removing the weed block from her yard, section by section, so that I can do weeding.

Back to your plants: I think it's much more likely that the rainwater is unable to properly evaporate, that the soil cannot breathe, etc. The wood chips on top of the weed block may look nice, but I personally don't know of any biological function they're serving at the moment other than to complicate the respiration cycle. Nitrogen-robbing sounds unlikely in view of the separation of the wood chips from the soil by means of the weed block plastic/geotextile.

Cynthia H.
Sunset Zone 17, USDA Zone 9

[St. Louis gardener]

It's more of a weed barrier fabric, a kind of mesh, so air and sun and water can find their way through it. It doesn't keep ALL weeds out, but enough of them that I don't have to pick weeds every day. I have enough of that to do in my lawn! The thing about it is, everything EXCEPT the tomatoes (and them to a lesser degree the last few days) and the sweet peppers are thriving under these exact same conditions. Potatoes aren't rotting in the soil. Squash and cukes and pole beans and lettuce doing well. The only thing I'm having trouble growing (from seed) is eggplant. These tiny buggers don't want to grow, even though they're not dying.

[cynthia_h]

The plants you're having the most difficulty with are all related to one another.

Tomatoes, peppers, and eggplant are all members of the Solanaceae family, also known as Nightshades. Potatoes are also members of this family; are your potatoes being grown under the weed barrier? If so, how do you plan to "hill up" to keep the spuds from seeing daylight and developing the green skin which cannot safely be eaten?

There has got to be a connection between the growing conditions and the fact that the Solanaceae are the plants most affected. Perhaps a dedicated Internet search will uncover specifics of what these plants need in their culture that others do not:

--more transpirational capacity?
--lower soil temp?

etc.

Cynthia

[St. Louis gardener]

Good point, except that the tomatoes have pretty much bounced back since the everyday rains stopped a few days ago. I decided to do my potatoes in mulch hills instead of hard dirt to make it easier to harvest. My mulch hills are obviously on top of the weed barrier. They are about a foot high now. Since I expect the plants to grow higher, and I can't guarantee I'll be able to keep my little mulch "teepee" in place, especially when it rains, I thought I'd try a trick I saw on this forum: putting chicken wire around the plants to keep the mulch in and as they grow filling in with more mulch. I understand the top leaves need to be left uncovered so the sun can work its magic, so how far from the tops of the plants should the mulch be piled?

[cynthia_h]

When we grew potatoes in the "potato tower" kind of box (2008), I would add material to cover the plants such that approx. 1/2 of the leafy plant was exposed to the sun. I added this material once or twice a week, depending on how fast the plants were growing.

Cynthia

[St. Louis gardener]

Thanks Cynthia, for sharing!!

[garden5]

Here is a resource that may help you out:

Pepper Fact Sheet

Notice that it says:

Pepper plants grow best in warm, well-drained soils of moderate fertility and good tilth. The plants are not particularly sensitive to soil acidity, but best results are obtained in the 6.0 to 6.8 pH range.

This tells me that your soil may just be water-logged and needs to dry out more. How is the soil that the pepper are growing in since it has stopped raining for a few days?