D3137: Chemigation spray deposition efficacy on corn for the control of western bean cutworm (Striacosta albicosta Smith)

Striacosta albicosta is an insect pest that can cause severe damage on corn ears by larval feeding. Inadequate insecticide application may lead to failures of S. albicosta control in corn. Exposing this pest to sublethal dosages may lead to the development of insecticide resistance. Therefore, good coverage of treated plants must be achieved for the control of S. albicosta. In intensive corn production in Nebraska, the majority of growers apply insecticides by airplane, but spray coverage is not uniform. On the other hand, some growers apply insecticides by irrigation system (chemigation), but there is little information available for chemigation efficacy against this pest. Thus, the goal of this field study was to determine which nozzle package and carrier volume would provide the best deposition efficacy and coverage of insecticides. A tracer dye (PTSA) was used to measure spray deposition on corn plants. PTSA was applied through center pivot at low and high carrier volumes of water (0.25 and 0.75 acre-inches). Plastic jars positioned at tassel and ear height were used to collect chemigation samples. Leaves from the same height as jars were also collected. Samples were analyzed by fluorimeter. Leaf area was measured by leaf scanner.