An Environmentally Friendly Pesticide Curtails Cotton Pests

Two of cotton’s worst enemies are conceding to an environmentally friendly insecticide called spinosad. Approved for use on more than 100 crops--including apples, almonds, citrus, eggplant, tomatoes, cotton, and coffee--spinosad is poised to replace malathion, until now the most widely used insecticide against the Mediterranean fruit fly.

Agricultural Research Servicescientists in College Station, Texas, have years of expertise developing new tactics to test this new insecticide on commercially-grown cotton. Cotton bollworms and budworms have developed resistance to most commonly used commercial insecticides. As a result, these insects now infest over 75 percent of the U.S. cotton crop.

Aerial applications of spinosad were applied with a small droplet size (200 micron) and a 5-gallon spray rate. Commercial cotton treated at this level had fewer damaging bollworm and budworm larvae compared to cotton treated with other pesticides. Larvae found on cotton treated with standard insecticides were more mature, suggesting that spinosad prevented small larvae from becoming larger and more damaging. Typically, spray rates for standard insecticides average about 2 to 3 gallons per acre.

The Texas study was conducted through a trust fund cooperative agreement between ARS and the makers of spinosad, Dow AgroSciences LLC, of Indianapolis, Ind. Just as important, these studies established that spinosad is nontoxic to beneficial insects like lady beetles and pirate bugs. More beneficial insects were found on cotton treated with spinosad, but fewer of them survived on cotton treated with standard insecticides.

ARS is the chief research agency for the U.S. Department of Agriculture.

Scientific contact: Ivan W. Kirk, Areawide Pest Management Research Unit, College Station, Texas, phone (979) 260-9584, fax (979) 260-9386, [email protected].