FIELDAND
FORAGE
CROPS
FIELD
The information and recommendations in this newsletter are applicable to
North Carolina and may not apply in other areas.
Although we are again off to a late, generally wet start this growing season, weather patterns are hard to predict with any reliability beyond about a week. Additionally, our mild winter does not necessarily mean that we are more likely in for a rough insect year on cotton -- we have had too many exceptions in the past. Many of our more common insect pests such as bollworms undergo several generations prior to invading cotton, and the weather patterns between early May (initial emergence of spring bollworm moths) and mid to late July will be much more influential in determining the timing and intensity of moth flights than the winter weather. I will try to keep you abreast of bollworm and other insect levels, and their potential damage as these populations develop through the upcoming season.
Thrips should remain our only potentially-significant insect problem from cotton plant emergence through early to late-June over most of our state. A recent article on at-planting options for thrips control and another about expectations for Bollgard performance will be posted shortly in Keith Edmisten's Cotton Notes. You might also refer to the 1998 Cotton Information for additional information on thrips. Thrips scouting information can also be found in the Cotton Insect Scouting Guide. Finally, thrips management advice is also archived in previous years' issues of the North Carolina Pest News. I will have more information on scouting and damage symptoms in the coming weeks.
A reformulated version of Payload 15G at-planting insecticide should be available this year; the manufacturer claims that this new product should be free from the bridging (i.e., stopping up) problems which have plagued Payload in the past.
For growers using Gaucho-treated cotton seed, I would suggest that producers and consultants inspect seedling cotton particularly carefully for immature thrips and damage. Although this product has shown yields similar to Temik in extensive testing in North Carolina for two of the past three years, Gaucho's persistence (typically about three weeks) has consistently been less than other at-planting alternatives, particularly Temik 15G. For late-planted cotton (after May 15) the anticipated faster grow-off places less dependence on persistence. Payload may have a good fit for this late-planted cotton.
Foliar treatments for thrips following an at-planting material should be made with discretion and based on need, as these treatments can greatly increase the probability of having to also treat for June tobacco budworms or bollworms, particularly in the southern half of the state (except with B.t. cotton which is extremely resistant to budworms). As was the case in 1997, foliar treatments can also increase the odds of a subsequent aphid and/or spider mite problem. However, with high thrips populations and delayed seedling grow-off, foliar application(s) for thrips can significantly reduce maturity delays and yield losses. In North Carolina, approximately 25 percent of the cotton acreage is treated with a foliar insecticide for thrips; last year that figure was over 50 percent, with some fields treated two or three times. Do not overlook the possibility of having to treat as early as the initial appearance of the first true leaf.
Within the next few weeks, we should begin to get the first indications from Florida and Georgia of how their insect populations are shaping up. Thrips, early tobacco budworms, plant bugs and cotton aphids will be of interest. I will try to pass some of this information along. General southeastern insect trends sometimes become established early.
For our later economically-damaging insect pests, primarily
bollworms and European corn borers, the weather between now and the
major moth flights and the attractiveness of the cotton crop will
largely determine the extent of potential damage. Not much can be
predicted now, except that our 1998 cotton crop is slightly behind
schedule.
Web page last updated on April 24, 1998 by Stephen J. Toth, Jr..