Cotton Pest Management Newsletter #2
May 31, 2001

Cotton Situation: The Georgia Weekly Weather and Crops Report for the week ending May 27th listed the crop as 79 percent planted and 3 percent squaring. These estimates are slightly below the five year averages. Much needed showers were received in many areas and planting operations are continuing at a rapid pace.

Insect Situation: Thrips injury may still be observed on late April and early May planted cotton. Foliar treatments were needed in some areas. Isolated reports of grasshoppers and cutworms have also continued during the past week. A new observation included high populations of false chinch bugs in some conservation tillage fields in southernmost Georgia. As cotton begins to square, scouts should be in the field. We could potentially see tobacco budworm eggs during the next week.

Thrips: The high populations of thrips observed in recent weeks appear to have decreased in recent days. Much needed rainfall also allowed plants to uptake at-planting insecticides in droughty fields. Foliar sprays were needed on some acreage during the past week, but some damage (crinkling of expanding leaves and stunting) may still be observed in fields which were heavily infested. Continue to monitor fields for thrips until seedlings attain 5 true leaves and are growing rapidly.

Tobacco Budworm: The first generation of tobacco budworm (TBW) generally occurs in late May or early June in southernmost Georgia. As you move north, that date is delayed somewhat. We would anticipate most of the activity on older squaring cotton but infestations may occur on pre-squaring cotton. During recent years, natural controls such as big-eyed bugs, minute pirate bugs, fire ants, etc. have provided suppression of early TBW. Every effort should be made to conserve beneficial insects, especially on non-Bt cotton. If intervention with insecticide is needed, selective chemistry such as Tracer, Steward, or Larvin should be used. Many growers have successfully elevated TBW thresholds in June to 10-15 larvae per 100 plants when high numbers of beneficials are present. However, if beneficials fail to suppress small larvae, growers must be prepared to react promptly. For example, if a scout reported 10 eggs, 12 small larvae, 0 large larvae, and high beneficials, a grower might delay treatment until the field is scouted again in 3-4 days. If the large larvae counts remains low or at zero, the natural controls are doing their job. However, if the large larvae count is high, the grower must react promptly. Larvae are considered large if they are greater than 1/4 inch in length. The size of "bollworm" larvae of known age reared at 85 degrees F are as follows:

Plant Bugs: Plant bugs are not a widespread problem in Georgia. However, they can be an economic pest and thus require scouting. As cotton begins squaring, be sure scouts are monitoring retention and are observant for adult plant bugs which may have migrated into fields.

False Chinch Bugs: False chinch bugs are generally associated with dry conditions. Unfortunately, that has been the case for the past several years. Will Duffie reported high populations in some reduced tillage fields in Brooks county. Adult false chinch bugs are slender, about 1/8 inch in length, and grayish with clear wings. Nymphs are brownish-gray in color and scurry around quickly on the ground. False chinch bugs are sucking bugs and consume plant sap when feeding on the leaves and main stem. In severe situations, stand loss may occur due to the added stress resulting from feeding. Stand loss problems I have observed have generally occurred on cotyledon cotton. No insecticides are labeled for false chinch bug control in cotton, but a high thrips rate of Bidrin, dimethoate, or Orthene should provide suppression. Additionally, pyrethroids or Lorsban used for cutworm control may also provide suppression. Adults may reinfest fields following treatment. Based on observations last season, cotton which has attained 4-5 true leaves and is growing rapidly is less likely to suffer damage.

Scout Schools:
June 4, 2001 Tifton (RDC)
June 5, 2001 Evans Co.
June 18, 2001 Burke Co.

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