Tomato trouble?

Asked June 15, 2017, 1:28 PM EDT

Dear experts - The leaves at the tops of my tomato plants are curling, stunted, and sparse. An occasional one is brown, but not the majority. The stems are fine though. The bottom leaves seem fine in size, shape, and number. We have watered about the same amount that we usually do. One thing that is different is that we are planting in brand-new topsoil (containing compost) from a local vendor. A week ago we side-dressed (judiciously, I think) with additional compost made of worm casings. At that time I thought the plants were small, but did not have the issue I am describing now. What do you think the trouble is? Thanks as always, -Jim

Howard County Maryland tomato herbicide contamination

4 Responses

The curling and twisting and undersized leaves are probable symptoms of herbicide contamination. Tomato is sensitive to certain types of growth regulator fertilizer.The most common culprit is 2,4-D. Very small amounts of 2,4-D can drift a great distance from the site where it's sprayed and land on garden plants. In other cases the herbicide is applied as a "weed & feed" product and is carried off-site by rainfall and gravity to garden sites.

The least likely scenario is that your compost is contaminated with other types of herbicides that act as growth regulators (clopyralid or aminopyralid). Problems with these herbidides have been far fewer in recent years because there use is more restricted. But it would be a good idea to test the garden soil with the compost using the bioassay test in this publication:

Essentially, you plant pea or bean seeds in some small containers containing the soil and compost and observe the growth of the seedlings.

Regardless of the source of the herbicide the prognosis is not good. Although your symptoms are not severe new growth may continue to exhibit the problem. The abnormal growth will greatly reduce yields. You may want to re-plant if you can find transplants or plant new plants in containers nearby.


JT - I had done some internet research of images and the closest I came to was herbicide damage. Another fact about my garden is that in looking around the community garden I don't see this anywhere else. Corn in an adjacent raised bed on the same soil, is growing pretty well, although not quite as well as some next-door neighbors' plot. In addition, there are 2 tomato plants that look a little funny but are growing quite a bit more than others. Another observation is that basil seeds just failed to grow at all. At home, where I think I mixed the soil with old potting soil, I am getting some basil seedlings.I guess it could be very local drift of the herbicide? Or individual susceptibilities? I am distressed over the news, but thankful for your replying so quickly. -Jim

It's very possible that a little bit of 2,4-D drifted in and only affected your plants. You might want to walk around the cg and see if any other tomato plants are affected.

Corn is a grass and not affected by these broadleaf herbicides.

You may want to do the bioassay test to rule out the compost. Good luck.

JT - Wow. And that would explain, I guess, why the plants looked pretty ok for a while, then began to wither. You are very kind to continue to answer my long questions. I really appreciate it. -Jim