Last week on June13 while sampling field plots in corn near Hart, Tx there were extremely heavy thrips pressure. Clouds of thrips hovered around us while walking through the corn field. These heavy thrips densities had dispersed when sampling the field plots on June 20. But, the thrips had cleaned up the spider mites that were beginning to develop in these fields. We could find a few spider mites away from the field edges. Can we expect that spider mites will not be able to build back or with fewer spider mite numbers and fewer spider mite predators will the mites develop to damaging infestations? So, it still should be prudent to continue scouting for spider mites. And, for late planted cotton with fewer than five true leaves scouting for thrips should continue.
Southwestern corn borer moth activity has begun to increase in a few counties on the Texas High Plains. So far, the SWCB moth activity primarily been in Dallam, Deaf Smith, and Moore Counties. These moths are coming out of overwintering and are laying the first generation eggs in the whorls of corn. Bt corn will provide good control of the larvae hatching for this egg lay. Even for non-Bt corn this first generation larval infestation usually does not cause significant damage. Begin looking for shot-hole damage to get an indication of the percentage of plants that are infested. Infestations rarely exceed 5 percent infested plant. Even if there is a higher percentage of infested plants, control treatments may not be effective since larvae may be deep in the whorl where the insecticides will not penetrate or the larvae may have already tunneled into the stalk.
|Southwestern Corn Borer - Shot Hole Damage. Photo: Dr. M. Rice|