R.E. Mickle and G. Rousseau
Deposit for dyed FORAY 48B and FORAY 76B to two 6ha (200m x 300m) collocated blocks was compared for two spray strategies. One block was sprayed using a normal application strategy of equally spaced swaths across the block. The other block was sprayed using an optimization technique developed from model (FSCBG/AgDRIFT) predictions based on application parameters (Cessna 188, aircraft height, 4-AU4000 rotary atomizers, drop size distribution) and local meteorology (winds, temperature and relative humidity). The two blocks were arranged as one 15ha (500m x 300m) block to allow for continuous spraying across both blocks on equivalent lines thereby reducing meteorological differences during the application. Five trials were realized.
Optimization strategies resulted in multiple passes (up to 6) on a single line displaced up to one half swath upwind of the block boundary. Swath displacement and multiple passes increased with increasing wind speed.
Measured deposit within the optimized block showed increases of 13% to 185% over deposit in the regular block (equal swath spacing). With increased deposit, average COV decreased from 0.64 to 0.43 reflecting the more uniform deposit across the block sprayed using the optimization strategy. Similar results were found for drop density with optimized to regular block ratios ranging from 1,0 to 2,87. Average COV declined from 0.75 in the regular block to 0.41 in the optimized block.