BAS-125, A Promising Vegetative Growth Control Chemical for Bearing Apples

Abstract

Handgun applications on bearing spur `Red Delicious' evaluated both timing and concentration. At season's end, single 250-ppm applications at petal fall (PF), PF+7, +14 or +21 days reduced growth by 47% to 67%. Concentration of 125, 250, and 375 ppm @ PF+7 were all effective (45% to 55% reduction). Number of pruning cuts, pruning weight, and pruning time were all reduced. Applications at PF+0, +7 and +14 days increased fruit set, and, as a result, fruit weight trended lower. Airblast applications to `Top Red Delicious' applied at PF+3 weeks using 125, 250, and 500 ppm showed good initial growth suppression, but considerable regrowth in August and September. Yet, pruning weight and tree row volume were reduced with no fruit set or quality differences. Multiple, low-rate applications starting at PF on `Granny Smith' were very effective (60-70% reduction). Total application concentrations of 250 ppm were more effective than 500 ppm. The earlier the application sequence was started, the better the growth suppression. Two years of successive 200-ppm applications to the same trees in five separate plots involving three varieties showed an average 32% reduction in year 1 and a 56% reduction in year 2.