Without effective acaracides to control spider mites, a grower can lose 50 percent of his cotton crop, according to University of California Extension Entomologist Larry Godfrey.

The more miticides available to control mites, the better chance growers will have to avoid damage, Godfrey told pest control advisers and growers at the recent Cotton Technology Seminar sponsored by Bayer CropScience in Carmel, Calif.

Although there can be resistance to Kelthane and Comite if repeatedly used within a season, California cotton growers have generally dodged the resistance bullet that has been documented elsewhere in the world to 81 different pesticides used to control spider mites.

Zephyr is one of the most widely used miticides in California’s San Joaquin Valley. It has been used for eight seasons and in only one of those years in the late 1990s was resistance documented. It has never come back.

Comite and Kelthane can be used effectively if used early when mites are most susceptible and not used more than once per season.

Fortunately for resistance management, there are several new miticides on the market or soon to be registered, including Acramite, Fujimite, Zeal and Oberon.

Oberon from Bayer is expected to receive registration soon. It is also effective on silverleaf whitefly and that makes it even more welcome.

It also is a new class of chemistry, also a welcome addition for resistance management.

Godfrey added, however, that Oberon is not effective against aphids.

Oberon is comparable to Zephyr for mite control, said Godfrey and comparable to Assail, Knack and Courier for whitefly control.

"Oberon is a good fit where you have both spider mites and whitefly," he added.

e-mail:hcline@primediabusiness.com