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New Mexico State University

New Mexico State University

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Dry winter may mean better chile, pumpkin crops

LAS CRUCES - The dry fall and winter may be a boon to the $40 million New Mexico chile crop, which in wet years can be hit hard by a tiny, virus-carrying insect.



New Mexico State University project aide Jaime Rascon checks card traps for beet leafhoppers at a farm north of Las Cruces. The bright yellow cards attract leafhoppers, which spread disease among chile plants. (NMSU Agricultural Communications photo by J. Victor Espinoza


Virologist Rebecca Creamer, an associate professor in New Mexico State University's entomology, plant pathology and weed science department, expects a loss in New Mexico's chile country of just 1 to 5 percent due to the curly top virus, which is spread by the tiny beet leafhopper.

That would be a much smaller loss than that experienced by farmers in 2001, when a wet fall and winter helped leafhoppers thrive and cause 30- to-50-percent crop losses.

"We do seem to have it worse in odd years, for whatever reason," said Creamer, who has been studying the insect for NMSU since 2001. Losses were only a half percent to 1 percent in 2002 and 5 to 10 percent in 2004. Last year, 20-percent losses to the chile crop were compounded later in the season by 50-percent losses to pumpkin growers in Torrance County.

Leafhoppers take refuge in weeds that grow through the fall and winter, especially London rocket, a member of the mustard family that can flourish in the Rio Grande Valley. Wet years mean more weeds and better conditions for leafhopper survival.

In late April and early May, leafhoppers move from weeds into cropland, sometimes traveling 50 miles or more.

"They are good fliers and they move with wind currents," Creamer said. Even though the leafhoppers that farmers find on their fields may have come from miles away, it's still a good idea to keep weeds as controlled as possible to eliminate shelter for the insects.

"Be diligent with weeding," Creamer said. "If they don't have to move very far to find food, even the poor fliers can transmit the virus." Creamer also suggests that farmers plant more chile seed and let the virus do their thinning, especially in a year when relatively low losses are expected. The use of insecticide also can help control leafhoppers, but that's not economical in a light year.

The curly top virus also can affect home gardens, where chile and tomato plants are vulnerable, but display different symptoms. In chile, the virus causes stunting and yellowing, as well as thickened stems. No chile pods will develop. In tomatoes, the leaves will roll up.

"It sort of looks like you forgot to water them," Creamer said.

Regardless of whether it's the virus or another problem, gardeners shouldn't expect to spot the triangular, grayish-green insects; they're about the size of the tip of a pencil.

"Generally, they won't see the leafhopper," she said. "They see the plants coming down with the disease."

Still, it's best to wait a while and be sure plants are really infected before removing them from a garden. Heat- or water-stressed plants may appear to be infected, but can rebound when conditions improve. If it is curly top, the damage has been done.

"Once they're sick, there's nothing you can do about it," Creamer said.