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New Mexico State University

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Odds of Tomato-Killing Virus Look Less Likely This Season

LAS CRUCES -- The prognosis for growing tomatoes and chile looks brighter this year than in 1995, when a plant disease ravaged many fields and gardens, a New Mexico State University plant pathologist said.

Last season, cool spring weather allowed tiny insects called beet leafhoppers to thrive and spread the curly top virus from weeds to fields and gardens.

"It's too soon to say for sure, of course, but it looks as if conditions are less favorable for another widespread outbreak of curly top virus," said Natalie Goldberg with NMSU's Cooperative Extension Service.

"This year, we haven't had as much winter moisture and we're not seeing as much of a winter weed population, which should be a plus for us," Goldberg said. "But it hasn't been cold enough to kill off a significant portion of the insect population, so we should still have the insect factor. Hopefully, it will warm up more rapidly this spring, reducing the insect numbers and severity of the disease."

Both the virus and leafhoppers survive the winter in weeds. After feeding on infected weeds, leafhoppers can acquire the virus. When crops and gardens come up, the insects move to these host plants and spread the virus while feeding.

Curly top virus is present every year, but typically not on the scale of 1995, Goldberg said.

Gardeners and growers who had curly top problems last year, won't necessarily see problems again this season, she said.

"The virus survives in weeds, not soil, so it's important to do everything you can to reduce your weeds," Goldberg said. "To be most effective, though, weed control needs to be area wide, because leafhoppers can move long distances, especially when aided by the wind."

Providing plants with adequate water and fertilizer also will help reduce disease problems.

"Proper care makes plants strong and healthy," Goldberg said. "Weak or stressed plants are more susceptible to all diseases."

If all else fails and you see plants with the telltale signs of curly top, pull them up immediately, Goldberg warned. Curly top symptoms include slow growth, yellow, curled leaves and thickened stems. Infected tomato plants typically have purple veins in their leaves.

Since the disease has no cure, removing diseased plants is the only way to help keep the virus from spreading to the rest of the garden or field, she said.