FIELDAND
FORAGE
CROPS
FIELD
The information and recommendations in this newsletter are applicable to
North Carolina and may not apply in other areas.
The recent and widespread rains brought about by the remnants of Tropical Storm Earl should further reduce populations of cotton aphids and beet and fall armyworms. Our aphid-preying fungus should get a nice boost from the moisture to help clean up most of the remaining aphids and wash off honeydew, especially where conditions had been dry. We can still expect to have scattered colonies of aphids throughout North Carolina as cotton begins or continues to open. Only on very rare occasions are aphids present at treatable levels in opening cotton.
This time of year, especially under wet conditions, establishment of fall armyworms at treatable levels is unusual. Scattered beet armyworm populations, mostly at very low levels, were in evidence this past week. With this week's cooler temperatures accompanied by rain, beet armyworms should very difficult to find anywhere in the state. This phenomenon occurred in 1995 following a September 1 Section 18 Emergency Exemption for Confirm insecticide for an intense beet armyworm outbreak in Sampson, Harnett and Cumberland counties. Very cool, rainy conditions followed the day after the declaration, and approximately 10 gallons of Confirm total were used for the whole area to avert the crisis. The weather had simply eliminated the beet armyworms by disease.
The potential still exists for scattered infestations of bollworms and budworms in very late cotton which is still blooming and has a number of small and medium bolls. Insecticide treatment thresholds for bollworms should be raised to approximately 12 percent live caterpillars on fruit if larger, protected bolls are not included in the sample. At this point, it probably does not pay to treat cotton regrowth above a primary crop which has started to open. Budworms are mentioned as they have been mixed with bollworms to a significant degree this year. Budworms occurring throughout our major bollworm moth flight have contributed to the difficulty with control.
Early this past week, the number of boll weevils in the Conetoe area of Edgecombe County reached almost 180. This is certainly not an economic (yield-reducing) infestation for the producer(s) involved, although the 4,000-plus traps and the acreage treated with insecticide will be costly. Remind producers to try to avoid mowing traps, to replace those which are down, and to report any missing traps. Defoliation through mid-harvest is typically the most critical time to capture the offspring of any boll weevils which may have been brought into our state last fall or this spring. An update on the status about any additional weevil captures should be provided by Lloyd Garcia of the North Carolina Department of Agriculture and Consumer Services. The Department is very aware of this development.
The presence of fall armyworms continues in peanuts as does the presence of corn earworms. The threshold at this time of year is 8 or more caterpillars per square foot. Fall armyworms are less damaging to peanuts than corn earworms and the treatment threshold for an infestation of armyworms should probably be at least 10 to 12 fall armyworms per row foot.
Rains from Hurricane Bonnie helped reduce spider mites in most
areas. Now is a good time to check any untreated fields for
southern corn rootworm injury. The injury is easiest to detect
before any severely-damaged pods begin to rot. By checking
untreated fields or untreated strips in fields otherwise treated
with insecticide, growers can get an indication for the seriousness
of the rootworm problem in that location. This helps build a
strong base of useful information for making future decisions on
the need to treat preventively for rootworms.
Web page last updated on September 8, 1998 by Stephen J. Toth, Jr..