Departments of Plant Pathology and Entomology
North Carolina Cooperative Extension Service
North Carolina State University

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North Carolina Pest News
Volume 12, Number 20, September 5, 1997
Stephen J. Toth, Jr. and Thomas A. Melton, editors

The information and recommendations in this newsletter are applicable to North Carolina and may not apply in other areas.

From: Jack S. Bacheler, Extension Entomologist

Cotton Bollworm Update

The possibility of bollworms becoming established on cotton continues to decline with advancing cutout. A very high percentage of cotton fields are now safe from bollworms, especially those that are presently clean. However, some moderate numbers of adults caught in light traps and observations have supported the finding of locally high egg laying (mostly in the terminals) in a number of green, squaring fields. In these situations, if boll monitoring is confined to the medium and smaller bolls in the upper 1/3 to 1/4 of the cotton plant (i.e., the less damaged bolls further down the plant are not monitored), then a bollworm threshold of 6 percent or a little more is most likely appropriate. In these situations, however, looking at the larger bolls is still appropriate, as European corn borers and fall armyworms can sometimes occur more commmonly in the middle or even lower parts of the plants. Fortunately, with only a few exceptions, European corn borers and fall armyworms are not present in high numbers in most areas. Cotton fields with bolls to the top of the plants and without a residual population of bollworms, European corn borers or fall armyworms can probably be excluded from scouting, with little danger of economic damage.

Fall Armyworms on Cotton

Now that we are into September, fall armyworms will have a much more difficult time becoming established and growing to the point where they can damage harvestable fruit. Even second-stage (approximately 1/4 inch in length) larvae feeding between the square or boll surface and the inside of the bract almost always seem to grow slowly and die out after a week or so, especially with cooler weather. At this time, a threshold for fall armyworm treatment should probably be 6 to 8 percent or more live fall armyworms on squares or bolls. It is difficult getting a return on a treatment for fall armyworms at this time of year.

Cotton Aphids

Although cotton aphid populations are generally declining throughout most of the state, at least low levels of aphids are present in almost any field in which one cares to look. Sharp declines can be expected with defoliation. Spot checking fields with post-defoliation regrowth for cotton aphids is advised (especially in a year like this where the potential for regrowth is high).

From: Rick L. Brandenburg, Extension Entomologist

Peanut Insect Pests

Despite the cold nights recently, spider mites are still present in many peanut fields. However, the general trend toward cooler evenings this time of year will slow the mite's development and reduce the likelihood of major outbreaks. Corn earworm populations have been very light, while a few areas have fall armyworms present in peanut fields. This late in the season, 8 to 10 fall armyworms per row foot are required to actually cause any significant crop damage. Remember that unlike corn earworms, fall armyworms can persist in peanuts all the way to harvest.

Web page last updated on September 8, 1997 by Stephen J. Toth, Jr..

This Web version is a cooperative effort between the North Carolina Cooperative Extension Service and the Center for Integrated Pest Management