Graph showing yield advantage in bushels per acre versus spray date and crop growth stage. Yield advantage is the difference between sprayed and unsprayed strips within the same field. From 21 strip trials conducted in Ontario in 2003 between July 22 to Sept 4, the average yield advantage to spraying was 9.6 bu/ac. A field sprayed that reached thresholds at R3 stage of soybeans on July 22 yielded the highest at 20 bushels per acre. The majority of the trials were done between August 17 to August 27 with most in the R4 and R5 stage of soybeans. These yielded between 5 and 15 bushels per acre above the untreated strips. Yield response was observed when spraying took place as late as September 4 with two fields in the R5 and R6 stage yielding 9 and 7 bushels per acre, respectively. A yield advantage indicates that the yield in the sprayed strips were greater than the yield in the unsprayed check strips.

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