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From: Jack S. Bacheler, Extension Entomologist
Thrips levels have now picked up significantly across most of the state, primarily a result of our extended dry conditions and the continued drying down of cultivated and wild thrips hosts. A series of recent mid-40 degree nights and crusty soils have not helped much with seedling “grow off” either. Although we have witnessed a return to much warmer conditions and potentially better plant growth, rainfall is expected to be spotty at best for the coming week or more. This dry weather pattern is sure to further increase the level of migrating thrips and worsen potential damage to cotton seedlings.
Prolonged dry conditions also favor increases of hard to control (and difficult to identify) western flower thrips. Unfortunately, the first sign of western flower thrips damage to cotton seedlings is their virtually complete survival following a foliar application of normally-successful insecticide rates. About the best one can hope for in limiting damage from western flower thrips is a high rate Orthene or Monitor at approximately 0.5 pound of active ingredient per acre. Even these high rates may be disappointing against this species. Expect greater survival of western flower thrips following the seed treatments Gaucho Grande, Cruiser, Avicta and Aeris. For example, in a 2006 test near Rocky Mount at four weeks after planting, Temik 15G alone at five pounds of product per acre controlled 63 percent of adult western flower thrips compared with 30 percent control with a seed treatment followed by an Orthene spray (0.25 pound of active ingredient per acre) at three weeks after planting. Both of these treatments controlled over 96 percent of the tobacco thrips present compared with the untreated control. On the positive side, despite the above comments the western flower thrips is not the primary damaging thrips species in most cotton fields, even in dry years such as this when their levels may be higher than average.
Remember that the three week duration of seed treatment activity seems to be about the limit for thrips control under all kinds of weather. So watch that three week window and treat accordingly. In the fields that I have observed this past week, Temik appeared to be holding up well, although I have received a few reports today of “Temik cotton” in need of treatment at four weeks after planting. This was probably due to less than ideal activation under these dry conditions. Be sure to scout for thrips symptoms and the presence of live immature thrips before a foliar spray following Temik. However, with the forecast of another week of possible dry weather and continued migrating adult thrips pressure, producers may be justified in adding an insecticide with their herbicide, thus avoiding a second specific thrips treatment if thrips damage is likely over the next few days.
We are now into the post-April 20 planting period in which a seed treatment without a foliar spray will provide good thrips control. Temik 15G at three pounds of product per acre should also get producers through the thrips damage window.
In most years, adult migrating thrips levels drop significantly near the end of the first week in June here.
Over much of North Carolina’s cotton acreage, a good rainfall would work wonders for our struggling crop.
From: Stephen B. Bambara, Extension Entomologist
Surry County reported infestations of the white-margined burrower bug, Sehirus cinctus (image by Patrick Alexander). These are true bugs, but do no damage in the landscape. Adult females practice maternal care and feeding of young. This is unusual behavior for an insect and which is why they are often found in large "family" clusters and in huge numbers. Sometimes they are reported crawling on houses. These bugs are native, but are often reported feeding on the introduced "henbit", Lamium purpureum, which flowers and fruits in large numbers in lawns and agricultural fields in the early spring. It has also been reported on Plantain (Plantago). The maternal bugs carry the nutlets to their offspring in the burrow. They might be considered a problem if large numbers are found sucking the sap of tender seedlings. They could do damage in peanut and soybean fields. For some great pictures, visit the following web site: http://www.polyploid.net/bugs/bugs.html.
I mention this every year, but a beneficial predatory stink bug Euthyrhynchus floridanus (image by James Ward) is now appearing. The coloration of both the nymphs and adults (image by Stephen B. Bambara) is quite striking.
The adult of the greenstriped mapleworm (Dryocampa rubicunda) is called the rosy maple moth (image by Stephen B. Bambara). Adults are emerging now and laying eggs. Larvae (image by Lance Risley; http://www.forestryimages.org/) will be noticed in coming weeks. Larvae feed mostly on red maple and may be found feeding in groups. Larvae generally leave the major veins alone, but outer margin feeding gives the leaves a ragged appearance. This is usually not a problem, except on a specimen plant.
Flatid planthopper (image by James R. Baker) activity will begin soon with nymphal feeding and fluffy, waxy splotches (image by Stephen B. Bambara) appearing on tender shoots of many plants such as hosta, crape myrtle, hydrangea, maple, etc. The diagnostic characteristic is that they JUMP when you touch the fluff. As the summer weeks pass, the fluffy mass will expand a little. Eventually, the adults will depart and the residue will be left behind. Usually there aren't that many over which to be concerned, but if washing them off with a hose does not disrupt them enough, insecticidal soap or other suitable insecticide should be adequate.
We are beginning to see the build-up of crapemyrtle aphid on crape myrtles on the North Carolina State University campus. Aphid populations can explode within a week. If you have crape myrtles that consistently have a problem and have severe sooty mold, watch for these pests. Problems will become more noticeable throughout the summer. For more information on crapemyrtle aphids, see Ornamental and Turf Insect Note No. 31, which is available on the web at: http://www.ces.ncsu.edu/depts/ent/notes/O&T/shrubs/note31/note31.html.
Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age or disability. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.
Last modified on May 28, 2007 by Stephen J. Toth, Jr.
