Spray deposition evaluation on wheat anthers to study the head blight (Gibberella zeae) chemical control

The head blight caused by the fungus Gibberella zeae (Fusarium graminearum) is a major floral disease of wheat. The chemical control is efficient only if the fungicides are applied at the full anthesis to protect anthers. In this research, the main objective was to built such a spray boom to allow different spray nozzles arrangements. The anther staining provided by color dyes applied with different spray nozzles, nozzle arrangements, and spray volumes was also assessed. Two spray booms were used, one with individual nozzles spaced at 0.50 m and another one mounted with adjustable sets, also spaced at 0.50 m, each one having one nozzle forward (30º or 45º) and the other backward at an angle of 30º or 45º. The nozzle types used were flat fan, twin flat fan, and hollow cone. A total of four experiments were carried out. The deposition of color dye was higher on loose than on trapped anthers. The double nozzle sets resulted in increased spray volumes (200 to 400 L ha-1) and higher numbers of fungicide sprayed anthers. The nozzle types did not differ from each other. The anther staining was improved by nozzles positioned at 45º (forward and backward) but not at 30º.

spray booms; loose anthers; trapped anthers