A comparison of biological effect and spray liquid distribution and deposition for different spray application techniques in different crops

摘要

The objective of this study was to compare a selection of spray application techniques with different application volumes, with respect to the spray liquid distribution on flat surfaces, the deposition in fully developed crops and the biological effect. The spray application techniques in this study were conventional spray technique with three different nozzles: Teelet XR, Lechler ID and Lurmark DriftBeta, and also AirTec, Danfoil, Hardi Twin, Kyndestoit and Släpduk. The dynamic spray liquid distribution was measured on a flat surface, spraying a water and black dye solution on pre-glued wallpaper lengths. Spraying the same dye-water solution in established crops, the spray deposition on plant and on the ground was studied by measuring the absorbance of sampled leafs' and collectors' rinsing water. Spray deposition studies were made in winter wheat and potato. The biological effect was studied in field experiments with plots with linearly increased dose. The field trials in this study were weed control in spring barley, fungi control in winter wheat and potato late blight control. The weed weight was sampled and visual assessments were made of the infection of fungi. Grain yield and 1000-kernel-weight were sampled in the wheat trial. The dynamic spray liquid distribution resulted in coefficients of variation, for all spray techniques, between 5% and 16%, which were considered to be at acceptable levels. Relatively large significant differences were found in the spray deposition measurements in potato canopies. For conventional spray technique, 90% spray deposition was recovered in the top of the canopy. Higher deposition was recovered in the lower part of the canopy and on the ground for Danfoil, Hardi Twin and Släpduk than the other techniques. In the wheat crop, the differences in spray deposition between spray techniques were smaller. Släpduk had the greatest increase in liquid deposition on the head and the flag leaf. The techniques with external air assistance, Hardi Twin and Kyndestoft, had the lowest deposition on the ground. Analysing the effect of weed control in spring barley, fungi control in wheat and potato late blight control, no significant differences were found. This might be seemed remarkable when large differences in spray liquid deposition were found in the potato canopy. One conclusion could be that the penetration ability in dense potato canopies is not of equal importance as to protect the upper parts of the canopy. It is indicated that it could be important to consider other factors, not included in this study, such as the ability to reduce drift and increase capacity, when selecting spray application technique