The federal registration of Diamond insecticide, a broad-spectrum cotton insecticide with a unique mode of action, will help cotton growers achieve more effective control of escalating populations of plant bugs, stink bugs and other damaging, mid- to late-season insect pests.

Unlike conventional insecticides that attack the nervous system, Diamond controls insects by interfering with chitin development, which causes the target pest to produce a weak or malformed insect exoskeleton. Applied early when insect pests are in the larvae/nymph stage, Diamond prevents juvenile tarnished plant bugs, clouded plant bugs, stink bugs, armyworms, loopers, budworms and bollworms, cotton leaf perforators and saltmarsh caterpillars from reaching the next growth stage.

The introduction of Diamond allows growers to effectively control a group of pests once considered to be “secondary.” Cotton specialists agree that widespread adoption of transgenic Bt cotton, successful eradication of the boll weevil, and an overall reduction in the use of broad-spectrum insecticides have caused insect pests such as the stink bug and plant bug to emerge as primary cotton pests in states ranging from Georgia and Alabama to Mississippi, Louisiana and Arkansas.

Gary Lentz, research entomologist with the University of Tennessee, reports that stink bugs ranked as the number two cotton insect pest in Tennessee in 2003, behind bollworm/tobacco budworm. However, the bug complex, including plant bugs and stink bugs, caused the greatest losses in 2002.

University entomologists generally recommend use of a conventional insecticide when stink bugs reach a threshold of one bug per 6 row feet, or when plant bug populations cause at least 20 percent pinhead square damage or 10 percent damaged bolls in blooming cotton. Because Diamond will control juvenile insects, it should be applied at the first sign of nymphs.

“Replicated field trials have shown that Diamond is persistent and rainfast on plant tissue, and will provide at least 14 days of residual control of plant bugs and stink bugs when used according to label directions,” says Tim Weiland, technical manager at Crompton Corporation/Uniroyal Chemical. Because Diamond is safe to most beneficial insect species, it is highly compatible with IPM programs.

Diamond offers a good option in rotation with other classes of insecticides for resistance management. Re-application under heavy infestation may be required to protect new foliage.

Diamond may be applied alone for control of juvenile insects. Diamond may also be applied in a tank-mix combination with conventional pyrethroid or organophosphate insecticides, or in rotation with neonicotinoid insecticides for control of mixed populations of juvenile and adult insect pests.

Growers may make up to four applications of Diamond per season, and apply up to 42 total ounces per acre per season. Consult the label for specific application rates.

Diamond has been granted “OP Replacement” status by the EPA, with a worker re-entry interval of just 12 hours.