Thinning ‘Red Fuji’ apples using ethephon at two timings

A trial was conducted on five-year-old ‘Red Fuji’ apple trees on MM. 106 rootstocks at the Grove Research Station in southern Tasmania in the season of 1988-89. Ethephon was used to thin the fruit at 0,50,100,200,400 or 800 ppm at either full bloom (FB) or 14 days after full bloom (14 days AFB). The thinning response was described by fitting curves. Ethephon was a more effective thinner at FB than 14 days AFB, which contrasts with a previous finding. Mean fruit weight reflected thinning success with the most effective treatment being ethephon at 800 ppm at FB, achieving the target of 200 g per apple.