IMPACT OF VOLUNTEER WHEAT ON WHEAT INSECTS IN A WHEAT-SOYBEAN DOUBLE-CROP SYSTEM

The impact of the presence of noncompetitive levels of volunteer wheat, Triticum aestivum L. em Thell, in a summer crop on insect infestations in a subsequent crop of winter wheat was examined in a wheat-soybean, Glycine max (L.) Merrill, double-crop system in Georgia. The only insect collected from volunteer plants in large numbers was the Hessian fly, Mayetiola destructor (Say), although small numbers of thrips and aphids also were collected. Hessian fly immatures were not detected in volunteer plants before mid-August and were not prevalent until September. Hessian fly infestations were greater in volunteer plants that were present throughout the summer than in plants which were present only after mid-August. The presence of volunteer wheat in the soybean crop had little effect on hessian fly infestations in the following crop of winter wheat. Tillage probably disrupted Hessian fly activity and prevented the carryover of insects from volunteer plants to the subsequent wheat crop. Delaying planting of winter wheat by about one month greatly reduced fall infestations on the Hessian fly regardless of the occurrence of volunteer wheat in the previous summer crop.