Knowledgebase

Tomato “curl” and growth somewhat impaired #875382

Asked June 30, 2024, 5:41 PM EDT

Can you help with identification of a leaf malformation on my tomato plants? The leaves at the base of the plants seem unaffected, but from the mid-section up the leaves have done more than curl, but appear more like a tight corkscrew. Flowers are limited and in the week I have followed this none of those flowers have formed fruit buds. With difficulty I have unwound the leaves to find nothing that suggests a disease or pest problem-the leaf is still green throughout with no chewing or holes. I have 10-12 plants in a row, and interesting to find that a heathy Yellow Brandywine and a heathy Stripped German are separated by a deformed Stripped German-each about 3’ apart. Roughly 25’ away is another tomato plant (Lemon Boy) which looks as gnarly as the other deformed ones. As I write this after not checking these plants in several days, it ALMOST appears as though some of those affected leaves may be unwinding! I rotate my plants annually as well as I can given I have a small garden. One thought: Could a week of intense heat, then followed by rain and much cooler temps be something to consider? I have researched a number of State University websites and have come up empty, thanks for any advise you might have.

Chittenden County Vermont

Expert Response

Hi DeeDee,

Thank you for contacting the UVM Master Gardener helpline. I consulted with Dr. Ann Hazelrigg, UVM’s Plant Pathologist and her analysis is that this damage has been caused by either 2, 4-D broadleaf weed killer or the use of manure/compost that is contaminated with persistent pesticides. Herbicide injury usually occurs when weed control spray drifts onto nearby plants. In some cases, herbicides can drift many feet from the site of application. The 2, 4-D, if used for dandelions, can easily drift to gardens.

Symptoms of herbicide damage include leaves that grow in strange shapes, curl inward, and are smaller than normal. The damage from herbicide drift does not appear immediately and usually takes between a few days to 2 weeks for the damage to be evident.

Once plants display herbicide damage, there is not much to do but wait for them to recover. Vegetable and fruit plants are often able to outgrow herbicide drift damage over time, as long as they were not directly sprayed with the herbicide. However, their growth will be slower while they recover and they will take longer to start producing fruit. Plants may recover more successfully through regular watering and fertilization so they are not stressed in other ways.

The following are websites with additional information:

https://extension.umd.edu/resource/herbicide-damage-vegetables/

https://extension.umn.edu/yard-and-garden-news/noticing-herbicide-drift-your-garden

https://www.compostingcouncil.org/page/persistent-herbicides-faq

Hopefully your plants are able to recover and that you will have a bountiful harvest.

Melanie,  UVM Extension Master Gardener Volunteer Replied July 02, 2024, 7:57 AM EDT

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