Yellowing tomato leaves

Asked August 1, 2016, 11:28 AM EDT

2 days ago I sprayed a part of a tomato plant to test for phytotoxicity. The spray consisted of: 1 gallon distilled water, 1 tbs raw cold pressed been, 1.5 tsp agri silicone to emulsify neem,1/2 ounce azadirachtin, 2 ounces insecticidal soap, and 1 tbs daconil. The plant had earlier problems with early blight but It seemed to have cleared up. I noticed this morning in the area that I had sprayed 2 days ago the leaves are yellowing. (As you can see in attached pics) The other parts of the plant seemed fine. My question is does this appear to be a bad reaction to the spray, fungal issue, or something else?

Denton County Texas

11 Responses

It could be a spray burn, but I really don't think so; there is not really anything in the spray mixture that would cause a burn, although sometimes you do get a reaction with daconil and other products. I also don't think it is a disease reaction; it actually looks more like the aftermath of spider mite feeding. So you may check for spider mites and go from there; if severely infested your best bet is to take these plants out and start over. Fall is typically a great gardening season in Texas. Good luck!!

Thank you for the help. I have had issues with spider mites. I lost my bean plants to them.

I was wondering, how can you tell that the damage is from spider mites? Is there anything else to look for other than yellow leaves?

Also, are there any miticides labeled for use on vegetables? I can't seem to find much except neem, azadirachtin, and insecticidal soap...

You look for the yellow leaves and the small webbing like from a spider. If you hold the leaf in the sun, usually the underside, and look at it with a magnifying lens you can see the little critters scurry along. Go online and search for a product called Kelthane. Use this product when the mites first show up and the rotate with a soap of some kind. There are other commercial products such as Brigade and Agri-Mek, if you have large acres.

Thanks for the assistance.

I searched for kelthane and it's no longer sold. Seems that all miticides labeled for use on vegetables, except neem or azadirachtin, are difficult for most gardeners to get and if you can they are crazy expensive. I saw some posts from growers claiming they use Avid "off label" but I'm not going to risk that. If you by chance know where I can get some miticide labeled for vegetables please let me know.

I did spray Ortho Bug-B-Gone and Azadirachtin on the tomato plants yesterday after removing all of the yellow and dying leaves. I went outside today and even more of the plant is yellowed and dying. I removed the yellowing leaves again today and looked at several of them under a bright light with a magnifying glass. I couldn't see any mites at all. I tried tapping the leaves over white paper and still no mites. I've had mite problems before and I was always able to find mites. I can see them scurrying along the paper like little running dots. With the magnifying glass I can see they are insects. I can't find any mites on the tomato plants. No webs either.

The yellowing of the leaves don't appear to be any disease I'm familiar with. The leaves will start yellowing on the leaf edges. The yellowing then spreads to the entire leaf. Then the leaf will die (turn brown) from the leaf edge to the middle. Although, sometimes the yellowing starts on the leaf tip.

Could it be a disease I missed? It's been hot and dry here so I don't think conditions are too favorable for disease. Conditions are favorable for mites. Maybe the mites fed then ran? Do mites do that?
I've swapped out drippers from 1 gph to 4 gph. Maybe increasing the water will help. They are in 25 gallon well drained containers so over watering is unlikely.

What should I try next? I'd like to at least figure out for sure what's getting my tomato plants.

There appears to be some Kelthane available on ebay.

As you suggest it has been way too hot for a disease.

Yes, mites can come in and then leave. That has been apparent on pecans this year. This yellowing could be accentuated by low fertility and no doubt the heat is having a deleterious affect on the plants.

Your best bet may be to replant.

For the first time in days I didn't see any new yellowing on my tomato plants. Perhaps the bug-b-gone and azamax spray is working.

The azamax (azadirachtin) label sais it can be used as a drench. How effective is neem/azadirachtin when used as a drench? Do plants really absorb the azadirachtin when the soil is drenched with it?

The azadirachtin can be absorbed by the plants when applied as a drench, but not the neem oil. Glad to hear the plants are looking better.

Is using azadirachtin as a drench very effective for controlling mites or aphids on squash or tomato plants?

It may help; commercial farmers use products which contain imidachloprid.

Can you use imadacloprid as a drench on vegetable plants? If a vegetable plant absorbs an insecticide that was used as a drench won't that insecticide end up in the vegetables?

Will it harm any pollinators?

Thanks for your help....

Yes, when used according to the label it is safe. Will not harm pollinators.