ALTERNATIVES TO INCREASE AERIAL SPRAY DEPOSITS FOR FHB CONTROL

Authors: Kirk, Ivan; Fritz, Bradley - Brad; Hoffmann, Wesley

Submitted to: National Fusarium Head Blight Forum
Publication Type: Proceedings
Publication Acceptance Date: 12/13/2003
Publication Date: 12/13/2003
Citation: Kirk, I.W., Fritz, B.K., Hoffmann, W.C. 2003. Alternatives to increase aerial spray deposits for FHB control. In: Proceedings of the National Fusarium Head Blight Forum, December 13-15, 2003, Bloomington, Minnesota. p. 88-91.

Interpretive Summary: Some diseases of grain crops not only reduce production potential of those crops but also impart toxins and impair utility of the grain for food and feed uses. Fusarium head blight is one of those fungal diseases that has emerged as a serious problem of wheat and barley in some production regions of North America. A coordinated research effort to address this problem has been initiated with support of the U.S. Department of Agriculture. Control of the disease with aerial applications of fungicides is one of the control approaches currently being studied in this coordinated program. Three field studies of promising aerial spray application technologies were conducted to assess approaches that maximize spray deposits on wheat heads. The aerial technologies that were evaluated in these studies included spray rate and droplet size with conventional hydraulic nozzles, spray rate with rotary atomizers, and applying sprays in two directions over the same aerial swath. Rotary atomizers with spray rate of 5 gallons per acre gave maximum spray deposits on wheat heads. This range-finding research will be important in implementation of aerial application practices for control of Fusarium head blight in wheat and barley.

Technical Abstract: Development and evaluation of aerial application technologies to enhance the efficacy of fungicides and biological control agents with standard aerial spray rates was highlighted as a priority in the Chemical and Biological Control research area of the U.S. Wheat and Barley Scab Initiative for fiscal year 2003. The ARS Aerial Application Technology research team at College Station, Texas, was invited to assess aerial spray technologies that could increase spray deposits for Fusarium head blight control. The goals of the effort were to: 1) Identify the capability of conventional aerial application practice to deposit sprays on wheat heads and determine the properties of those spray deposits; 2) Determine if the amount of spray deposits on wheat heads can be enhanced through the use of very fine sprays produced by rotary atomizers, and characterize those spray deposits; and 3) Determine if aerial sprays applied from two directions would increase deposits on wheat heads, and characterize those spray deposits. Three large acreage aerial spray studies were conducted to achieve these project goals. Treatments were applied in randomized blocks with three replications. Multiple sub-samples of wheat heads and artificial collectors were collected and analyzed to characterize spray deposits from the specified treatments. Fluorometry and image analyses were used to quantitate and characterize spray deposits on wheat heads and artificial collectors. Fine droplet spectrum sprays applied with rotary atomizers gave the highest spray deposits on both wheat heads and artificial samplers. Medium droplet spectrum sprays gave the lowest deposits on wheat heads regardless of spray rates between 2 and 10 gallons per acre. Results from these studies on optimizing aerial spray deposits will be implemented in disease control studies to provide guidance for aerial fungicide applications for control of Fusarium head blight.