Cotton Pest Management Newsletter #12
August 22, 2002

Cotton Situation: The Georgia Weekly Weather and Crops Report for the week ending August 18^th listed the crop as 27 percent with open bolls. Crop conditions continue to be highly variable due to moisture stress. We have observed a few early planted fields which have been defoliated.

Insect Situation: Silverleaf whitefly has built to high numbers in parts of Tift and Colquitt counties. Caterpillar pests continue to be observed in fields which are lush and green. Bugs continue to be variable depending on location and insecticide use history.

Silverleaf Whitefly: Silverleaf whitefly (SLWF) infestations continue to build in Tift and Colquitt Counties. In addition to adults, high numbers of immatures have been observed in some fields. In fields infested with SLWF, it is a race to the finish. Some fields are very near maturity and will likely avoid serious yield impact, however later planted fields which are several weeks from maturity are at risk and will likely need treatment in these areas. In years past, Knack insect growth regulator has been the most consistent treatment for SLWF management. Knack must be applied before SLWF are out of control. Knack should not be used as a rescue treatment. Additional options for SLWF control include: Tank-mixes of Danitol or Capture plus Orthene, Intruder, or Thiodan (Thiodan only controls adults). These treatments will only provide temporary relief and multiple applications may be needed. Infestations of SLWF are generally more severe on hairy leaf varieties. See Newsletter #9 for additional information on SLWF biology.

Corn Earworm in Bt Cotton: Treatable infestations of corn earworm (CEW) escapes in Bt cotton were reported from a few fields this week. Bt cotton has provided excellent control of tobacco budworm, but historically a percentage of fields will need to be treated for CEW during the year. Often these escaped CEW are observed during mid-late July, but can occur any time. Be sure scouts are continuing to monitor for CEW and armyworms in Bt cotton. Pyrethroids are the treatment of choice for CEW.

Tobacco Budworm and Corn Earworm in Non-Bt Cotton: Mixed populations of tobacco budworm (TBW) and CEW continue to be observed in central and southwest Georgia. Most infestations are occurring in later planted fields or fields which are still green and lush. Infestations should be treated as a TBW infestation. Non-pyrethroid insecticides such as Steward or Tracer are recommended for control of TBW.

Armyworms: Fall, beet, and southern armyworms were reported this week from various parts of the state. Beet and southern armyworms are primarily foliage feeders, but will feed on squares, flowers, and bolls. Proper identification is important as insecticide selection will vary.

Soybean Looper: Soybean looper infestations can be observed in many areas. A few fields have required treatment. This is a pest which we need to watch, especially on later maturing cotton.

Boll Feeding Bugs: All fields should be scouted for boll feeding bugs until the last harvestable boll has attained 25 days of age from white bloom. We have mentioned in earlier newsletters that various species (southern green and brown stink bugs, plant bugs, and leaf-footed bugs) can damage developing bolls. This week we received a report of a heavy clouded plant bug infestation in an isolated field. Clouded plant bugs are not common in Georgia cotton when compared with states to our west. Typically this is a late season pest. Clouded plant bugs tend to feed more on bolls than the tarnished plant bug. Clouded plant bugs are larger than tarnished plant bugs, about ½ inch. Color is mottled or rusty with a mixture of gray, browns, and yellows. Legs of clouded plant bugs are yellow with darkened ends, and both adults and nymphs have long antennae.

Insect Updates: Check the Cotton Insect Hotline (1/800-851-2847) for updates on current insect conditions. The Cotton Pest Management Newsletter is also posted on the Internet at "www.gaipm.org" and then click on "cotton".

Sincerely,

Phillip Roberts
Extension Entomologist