Cotton Pest Management Newsletter #5
July 3, 2002

Cotton Situation: The Georgia Weekly Weather and Crops Report for the week ending June 30^th listed the crop as 76 percent squaring and 33 percent setting bolls. Crop conditions were generally listed fair to good, but some areas are in need of moisture very soon.

Insect Situation: Aphid populations are crashing due to the naturally occurring fungus in parts of the state. Tobacco budworm egg and larval counts are light to moderate depending on location. Beet armyworms continue to be reported and need to be monitored closely. Beneficial counts remain high. Stink bug scouting should be initiated on early planted cotton which is setting bolls.

Aphids: Aphid populations are crashing due to the naturally occurring fungus in some areas, mostly west of I-75. Scouts should be observant for grayish fuzzy aphids which are indicative of the fungal epizootic. Once the fungus is present in the field, populations will generally crash in about a week. Several county agents and consultants are participating in a Cotton Aphid Fungus Sampling Service being coordinated by Dr. Don Steinkraus of the University of Arkansas in cooperation with Cotton Incorporated. Results of samples sent from Georgia and other states will be posted on a web site by the University of Arkansas ((http://www.uark.edu/misc/aphid).

Tobacco Budworm: Tobacco budworm (TBW) infestations have been reported since early last week in southwest Georgia. Egg and small larvae counts have been moderate with a few hot spots. Reports of eggs in central Georgia have been received this week. Steward or Tracer are good options for TBW control, especially in areas where pyrethroid resistance is suspected. These products will also conserve natural enemies and control beet armyworm. Conservation of natural enemies will be important if beet armyworm activity is present in your area.

Corn Earworm: Scouts are reporting an increase in corn earworm (CEW) moth activity in southernmost Georgia. We would expect CEW numbers to increase during the upcoming weeks.

Beet Armyworm: Beet armyworms (BAW) continue to be reported from southwest and east Georgia. Beneficial insects have done a good job suppressing BAW in most areas; only a small percentage of fields have required treatment. In fields or areas where BAW are observed, it is important that natural enemies are conserved. Disruption of natural enemies could flare BAW infestations. The threshold for BAW is "Prior to full fruit set, apply when 5-6 active "hits" are found per 300 row feet; after full fruit set, treat at 10 active "hits" per 300 row feet." Beet armyworms lay eggs in clusters of about 80 eggs on the undersides of leaves. Upon hatching, the small larvae will feed in a group on the underside of the leaf, leaving the uppermost leaf surface intact which creates a "window pane" appearance or easily identified "hit". After feeding gregariously for several days, larger larvae will disperse on the plant and to neighboring plants. The threshold is based on "active hits". An "active hit" is defined as a hit which comprises greater than 20 BAW larvae 1/4 inch in length. In situations where beneficial insects are high, predators will prey upon small BAW larvae often reducing numbers to a few per hit. Once larvae reach 1/4 inch in length, mortality due to predation decreases. Larvae which escaped predation may be parasitized by Cotesia wasps. Immature Cotesia develop within their host, and can often be noted by examining the pest larva. If the back half of the host is an odd yellowish hue, the caterpillar may contain a parasite larva. One can confirm the presence of parasitism by gently squeezing the larva between your thumb and forefinger and popping the wasp larva out of the rear of the host. Before becoming adults, the wasps larvae emerge from their hosts (causing mortality of the host) and spin a single cocoon on the leaf. The cocoon resembles a grain of rice on the leaf. If treatment for BAW is needed, Confirm, Intrepid, Steward, and Tracer are good options. These treatments are selective and will conserve natural enemies. Steward and Tracer are also recommended for control of TBW and CEW. Confirm and Intrepid are specific to BAW and offer extended residual activity. Be sure to read and follow label directions.

Stink Bugs: Scouting for stink bugs should be initiated by the third week of bloom. At this stage of plant development, the older bolls are approaching the diameter of a quarter. Treatment decisions should be based on internal boll injury and/or stink bug counts. Stink bugs have been numerous to date in various crops.

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