Cotton Pest Management Newsletter #8
July 19, 2001

Cotton Situation: The Georgia Weekly Weather and Crops Report for the week ending July15^th listed the crop as 84 percent squaring and 48 percent setting bolls. Overall the crop condition is fair to good but some dryland fields are exhibiting drought stress. Showers were widely scattered during the past week and moisture is needed soon.

Insect Situation: To date, tobacco budworm populations have been light. Prior to this week a small percentage of fields have been treated for "worms." However, corn earworm activity increased this week and both Bt and non-Bt fields should be monitored closely. We continue to receive reports of "bug" damage to developing bolls. Both tarnished plant bugs and stink bugs are being observed in fields.

Corn Earworm: Corn earworm (CEW) numbers increased during the past week. It is especially important that scouts monitor the middle part of the plant canopy when corn earworm is present. As in recent years, corn earworm appears to be depositing a percentage of eggs in the middle part of the canopy. Eggs have been observed on dried bloom tags, square bracts, stems, petioles, and on newly expanded leaves in the terminal of plants. When eggs are laid in the middle part of the plant that is where the small larvae will be found. Be sure to examine bloom tags closely for eggs. Also, look underneath stuck bloom tags for small larvae boring into the tips of developing bolls. At each stop, scouts should examine a minimum of one bloom, one bloom tagged boll, and a boll lower in the plant in addition to the top 12 inches of the plant. Pyrethroids have generally provided very good control of CEW and will also control bugs if they are present in the field.

Bt Cotton: Be observant for possible corn earworm escapes in Bt fields. Corn earworm larvae larger than 1/4 inch in length are considered escapes and treatment is suggested if 7-8 are found per 100 plants. If escapes occur, they are typically observed in the middle part of the plant and are associated with blooms or bloom tagged bolls. We have received several reports this week of small CEW larvae feeding in blooms.

Tobacco Budworm: Tobacco budworm (TBW) moth activity is low and it appears the second generation has passed. We would anticipate the third generation of TBW in early August.

"Bug" Damaged Bolls (Stink Bugs and Plant Bugs): Internal boll damage has continued to increase in several parts of the state. This should be expected in that a small percentage of cotton has received an insecticide application that has activity on stink bugs and plant bugs. Several early planted fields have been treated based on the 20% internal boll damage threshold. Treatment options for stink bugs include pyrethroids or the OPs, methyl parathion and Bidrin. Pyrethroids would be the preferred treatment for stink bugs at this time. Pyrethroids will also control any CEW which may also infest fields. Although pyrethroids do disrupt beneficials, a single application may not be as disruptive to beneficials as an OP. In fields where CEW moths and eggs are observed, delaying treatment of bugs a few days is advisable if internal damage is not excessively high. Potentially, a pyrethroid application will be needed for CEW in the upcoming days. Additionally a bug spray will lower beneficial counts which would increase the likelihood of CEW eggs and small larvae surviving.

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