Lygus is the No. 1 pest across the Cotton Belt. The insect’s piercing and sucking mouthparts feed on developing cotton squares. Feeding on floral parts results in deformed blooms or missing anthers. The square usually aborts and falls to the ground. The end result is lost cotton yield and income.

Lygus ranks first in needed application sprays and control costs in cotton per acre. Beltwide, lygus costs about 30 percent of a grower’s investment in foliar control of all insect pests.

Almost 200,000 bales of lint — 92 million pounds — were lost to lygus in 2010. Yield loss and control costs have reduced grower income by about $150 million.

Crops including guayule, a new crop grown in Arizona for latex and rubber, can act as sinks and draw lygus out of cotton. Some crops can serve as sources and sinks according to how they are managed with insecticides or through managed cutting, including safflower or alfalfa hay.

The Arizona regional lygus ecology trials were conducted over three years in commercial cotton fields in Pinal County, the state’s top upland cotton-producing county.

“We identified guayule as a sink during the cotton fruiting period,” Ellsworth said. “Guayule attracts lygus away from cotton and serves as a sponge soaking up lygus from the surrounding landscape at a relatively short distance. Until this project we had only limited pest data on this crop and its relationship with lygus and cotton.”

In California, Pete Goodell, University of California statewide IPM program advisor, studied lygus in about 50 160-acre commercial Pima and (upland) acala cotton fields mostly in western Fresno County for three years. Goodell and his crew sampled cotton fields weekly through the various stages of lygus development, and mapped other crops located within 2 miles of cotton.

Goodell’s eagle eye followed lygus movement in safflower planted near cotton. Safflower can be a major source of lygus. Safflower acreage in California exploded in 2007 and 2008 due to a sharp increased demand for the oil crop.

“It was a mess,” Goodell said. “The area was hit hard by lygus for a six-week period. The safflower was supplying an almost endless supply of lygus into cotton. In 2009, the same acreage amount was planted but carefully situated to minimize the contact with cotton and managed to mitigate lygus movement into cotton.”

cblake@farmpress.com