Whats the best time to attack the sweetpotato whitefly strain plaguing southwest cotton?
When there are an average of 1-1/2 sweetpotato whitefly nymphs per square inch on cotton leaves. Nymphs, an immature stage of the pest, are most vulnerable to chemicals. Holding off insecticide spraying until nymph density reaches 1-1/2 per square inch allows growers to minimize chemical use and whitefly damage. The new whitefly strain, also known as silverleaf whitefly, has caused more than $200 million damage annually to U.S. crops since 1991. Besides cotton, it attacks dozens of vegetable and ornamental crops mainly in Arizona, California, Florida and Texas. Western Cotton Research Laboratory, Phoenix, AZ Thomas J.
