What's killing my tomato plants?

Asked September 7, 2017, 4:59 PM EDT

I planted two standard size tomatoes (an early girl and something like a beefsteak, but not as big), with basil next to them both (it's doing well), a lilac off to one side (doing well), and another grape tomato on the other side of the lilac. The grape tomato has done very well and even has 8-9 foot vines on it. However, the two standard tomatoes started wilting and turning brown, starting with the lower leaves and moving upward through the plant. Some of the tomatoes don't taste good (moldy sort of), but they have continued to produce, although it is a small crop and they have produced some abnormally small tomatoes. I water in the morning every day if there's no rain, and only an additional watering in the early evening if they look wilted. The limited evening watering took care of the earwigs that were eating them, but then the browning/wilting started! I tried watering with a liquid fertilizer, but it did nothing except perhaps boost the grape tomato plant. I have since removed the worst affected plant entirely, lest it be some sort of transmittable infection that could get to the grape tomato. I have trimmed off all brown parts from the other plant, leaving only a couple leaves and the stems where there are a couple tomatoes ripening still.

Adams County Colorado fruits and vegetables

1 Response

Hi, thanks for your question. It appears that your tomato may have late blight. See the following fact sheet for information on it: http://www.extension.umn.edu/garden/fruit-vegetable/plant-diseases/late-blight-tomato/. We could do a better diagnosis if you can bring in a sample. Be sure to bring some affected leaves and some unaffected (some with partial dieback is great). We're located at 9755 Henderson Rd Brighton CO 80601.

That said, be sure to clean all your tomato cages with a bleach solution at the end of this season to ensure no reinfection next season. It also sounds as though you may be watering too much. Generally plants need several deep and somewhat infrequent waterings (2-3 times a week maximum) to ensure good healthy root development. This could be contributing to some of the leaf dieback.
Let me know if you have any other questions