For many years, the head blight of winter cereal crops, caused by the fungus Gibberella zeae, was considered a disease of secondary importance. However, the increased frequency and yield losses associated with head blight in Southern Brazil have turned this disease into a major problem. Gibberella zeae enters the host plants through the anthers. To avoid infection, the fungicides need to protect the anthers from the fungus, which requires improved spray techniques. The role of two types of spray nozzles (single jet and twin jet), different nozzle arrangements, and two spray volumes on head blight control and grain yield were evaluated. The experiments conducted at the field, during the year 2000, showed that the fungicidal applications reduced disease incidence, the number of infected spikelets, and disease severity significantly. The grain yield was increased as well. The spray nozzles, nozzle arrangements, and spray volumes did not influence disease control and grain yield. The differences in grain yield between treated and non-treated plots made chemical control worthy, despite its low efficacy. Fungicidal sprays to control head blight should use nozzles that deliver medium to fine droplets, at a volume of 200 L.ha-1.
droplet deposition; spray nozzles; modified spray boom
