Twisted Tomatoes spreading concern in Ozarks gardens
CARTHAGE, Mo. – From backyard gardens to full-fledged growers, something twisted is happening to tomato plants in the Ozarks.
“The first sample came in around June 15 from Dade County,” recalls Robert Balek, horticulture specialist at the MU Extension Service.
A Dade County resident brought a portion of the suspect plant into the Dade County Extension office. MU Agronomy Specialist Jill Scheidt examined the sample there and realized it was not a typical case.
“At first, it looked like it could have been herbicide damage,” says Scheidt. “The leaves and stems were twisted and curled, but there were some differences between the sample and typical herbicide damage which told me it might be something else, something new.”
The sample had curled leaves and stems, but only in the top portion of the plant. Also, not all of the tomatoes in the garden had these symptoms. Another part of the mystery was that no herbicides were applied anywhere near the tomatoes.
The aptly named virus causes twisted, curly growth similar to that of herbicide damage, but there are subtle differences.
They may remain green or turn yellow with purple veins. As with other virus diseases, plants become stunted. Fruit will be deformed or fail to develop at all. Pepper, and bean plants also can be infected and show symptoms while plants next to them may show no symptoms and be virus-free. The disease spreads in a random fashion by an insect called the beet leafhopper, a very small, wedge-shaped, winged insect only a tenth of an inch long. It’s color varies from pale green to gray to brown. Given its size, the beet leafhopper can be very hard to detect, but there are things you can do to limit their contact with your plants and thus prevent the spread fo the disease.
Because beet leafhoppers prefer to feed in sunny spots, providing some shade for your tomatoes and peppers will discourage leafhopper feeding. Shade cloth can be placed over plants using stakes.
Not only will the shade discourage leafhoppers, it will also help tomato and pepper plants grow better and produce more fruit during the hottest summer months. Shade cloth can be purchased at most garden centers and home supply stores. If a plant shows the wilting and stunting symptoms of curly top, remove the plant.
The is no chemical treatment for the virus. Leaving a diseased plant in place will provide a source of virus for feeding leafhoppers to pick up and carry to healthy plants. Put disease plants in a garbage bag, seal it up and put it in the trash.
“The correct diagnosis is required to know how to proceed with the crop, the plants, and the soil,” explains Balek. “This certainly was an unusual specimen. Since then, more samples came in almost daily form Jasper County.”
Drift from herbicides such as Banvel or 2,4-D can cause twisting and curling of tomato plants, but so can a microscopic pathogen called Tomato Curly Top Virus.
Tomatoes are very susceptible to herbicide drift, sometimes from as far as a quarter mile to half a mile away. Cucumbers, peppers, and grapes are also very sensitive, and would all show symptoms in affected areas as well. If these plants are present and healthy while the tomatoes are curled, you can likely rule out drift as a cause.
Curling can result from herbicide residues in soils, brought in by contaminated compost or mulch, but this also would affect other plants in the same soil.
To be sure, do a bio-assy. Simply plant a few seeds of green beans near the affected plants. As the beans sprout and new leaves appear, they should be straight and smooth. Any curling could mean that herbicide residue is present in the soil.
While Curly Top Virus is one possibility, there are other diseases which can curl tomato leaves.
“If you are certain that no herbicide was applied anywhere near your tomatoes, and you have a clean bioassay on your soil, but you still see curling symptoms, contact your local extension office.
Contact Jill Scheidt at the Dade County Extension, 2 N. Main Street, Greenfield or phone: 417-637-2112; contact Robert Balek at the Jasper County Extension, 302 S. Main, Carthage or phone 417-358-2158.