Submitted to: International Agricultural Engineering Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 10, 2009
Publication Date: August 23, 2009
Citation: Fritz, B.K., Lopez, J., Latheef, M.A., Martin, D.E., Hoffmann, W.C., Lan, Y. 2009. Aerial spray deposition on corn silks applied at high and low spray rates. International Agricultural Engineering Journal. 11:Manuscript 1360. Interpretive Summary: Damage to sweet corn by corn earworms is a major concern to growers potentially resulting in severe economic impacts. Pest control is typically obtained through aerial application of insecticides, though limited guidance is available for applying optimum treatments. A series of field studies were conducted examining various spray rates and droplet sizes for maximum deposition of active ingredient onto corn ear silks. Generally, higher spray rates with larger droplets increased the amount of material deposited on the corn ear silks. The results provide aerial applicators with information on optimum treatments to control corn earworms and reduce crop damage in corn.
Technical Abstract: Corn earworm is a major pest of sweet corn, especially when grown organically. Aerial application of insecticides is important for both conventionally- and organically-grown sweet corn production as sweet corn is frequently irrigated to assure return on investment given the high production costs. Aerial insecticide application costs can be minimized through use of reduced spray rates if insecticide efficacy can be maintained at the lower spray rates. The objectives of the study were to characterize deposition on field corn silks when applied at 46.8 L/ha (with VMDs at 230 and 400 micrometers) and 93.5 L/ha (with VMD at 400 micrometer) spray rates. Applications of the bioinsecticide Gemstar, and the insecticide Entrust, which are both approved for use in organic production, were made over three different fields. The amount of spray material deposited on individual silks for each treatment was determined. Deposition of spray material on the silks was very similar across all application treatments. Overall, the 93.5 L/ha rate resulted in the greatest deposition of active material on the corn silks. At the 46.8 L/ha rate, the smaller droplet size sprays resulted in less deposition than the other treatments.