IPM Cotton Projects, Safford Agricultural Center 1991

Abstract

In 1991 four Insect Pest Management studies were conducted to help understand the pink bollworm and aid in its control. The first two were replicated cage studies where cages were placed over the soil and insect emergence from the soil was monitored several times a week from January to mid-summer. The first had pink bollworm (pbw) infested bolls buried at 0, 2, 4 and 8 inches under the soil. The second had four plow down dates and sub -treatments of one or no irrigations. Perhaps due to the cold winter, few pink bollworm moths emerged in either study. In the buried infested boll study, no bolls buried at 8 inches produced pink bollworm moths in the spring and few emerged from either 4 or 2 inches. Of the bolls left on the surface, there was emergence from only some of the replications. Less than 1% of all of the potential moths emerged. In the plowing test, only 6 pink bollworms emerged in any of the 32 cages placed in the plots over the 18 weeks of the study. It appears to be a numbers game and the chance of having a pink bollworm emerge under a randomly placed cage in a field is very small. The second two tests involved Trichogramma bactrae, a trichogrammatid species imported from Australia. The first of these two studies involved placing laboratory produced pink bollworm eggs in a pattern around a release site for the parasitic wasps to determine their area of influence. This was done on three different occasions with varying success. The study was complicated by the fact that the wasp hatch must be coordinated with the pink bollworm egg deposition. Never-the-less, some pink bollworm egg parasitization took place. This study needs to be repeated. The second of these studies was two plots side-by-side, one treated with chemicals to control pink bollworm (and other insects), the other with weekly trichogramma releases during August and September. At the end of the season, 20 plants were removed from each plot and boll infestation and boll load were determined. The parasite controlled plots had a higher infestation level (35% to 23% with an LSD(05) of 9.9) than the chemically treated plots. There was no difference in the boll load between the two treatments. This study should be continued, preferably with a check plot so the value of the trichogramma can be evaluated more accurately.