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Producers Should Blast London Rocket Weed to Protect Chile Crop

LAS CRUCES - Rains that saturated southern New Mexico this winter created prime conditions for a deadly plant disease called curly top that could end up hurting a promising chile crop.

Mark Renz, a weed specialist with New Mexico State University's Cooperative Extension Service, says a bumper crop of London rocket weeds this winter is setting the stage for an outbreak of a plant virus that hits chile, known as curly top. (NMSU Agricultural Communications photo by J. Victor Espinoza)

"It can be devastating to commercial fields," said John White, Doņa Ana County horticulture agent with New Mexico State University's Cooperative Extension Service.

Fall showers germinated a bumper crop of weeds led by a species with a spacey name of London rocket. Then a rare series of winter storms dumped more than five inches of rain in the past four months, bulking up the weed supply.

"With all this water, these weeds are growing like gangbusters now," said Mark Renz, an Extension weed specialist in Las Cruces. "They're everywhere down here from yards to bar ditches."

The fast growing yellow-flowered weeds are the winter home of the beet leafhopper, which transmits curly top virus to chile and other garden plants, Renz said. Curly top, which can cut chile stands by more than half, stops growth and often turns plants yellow.

More importantly, infected plants will not produce any pepper pods, he said. Curly top virus affects home gardens, too, and tomatoes as well as chile.

Today, there is no natural resistance for the virus, White said. Since many cool season weeds are difficult to control chemically, the best prevention plan now is to pull, shred, mow or till these weeds before they produce more weed seeds and the leafhoppers get really comfortable, he said.

When temperatures rise this spring and weeds die back, the leafhopper will move to greener pastures, White said. But in this case, it will be green chile fields.

The last time New Mexico chile producers faced a difficult and expensive bout of curly top was 2001, when losses ranged from 30 to 50 percent across Doņa Ana and Luna counties, the state's top-chile producing counties, said Rebecca Creamer, an NMSU virologist.