Thinning ‘Red Fuji’ apples with ethephon or NAA

Publisher Website
Google Scholar
Abstract
A series of trials in Tasmania examined the thinning effects of ethephon and NAA on ‘Red Fuji’ apple. In the ethephon trials, concentrations from 25 to 600 ppm were applied at full bloom (FB) or 14 days after full bloom (AFB) to trees on either seedling or M.M.106 rootstocks. The NAA trial involved spraying concentrations of 5, 10 or 15 ppm at FB or 14 days AFB to trees on seedling rootstocks. Ethephon thinning of ‘Red Fuji’ was similar at FB and 14 days AFB. The dependence of fruit thinning on ethephon concentration was described by fitting non-linear response curves. These relationships were stronger and less variable for M.M.106 than seedling trees. Ethephon proved a satisfactory thinner for trees on both rootstocks. At the high spray volume used, the preferred concentrations at both FB and 14 days AFB would be 25 or 50 ppm for seedling and 100 or 200 ppm for M.M.106 rootstocks. NAA under-thinned at 5 ppm and over-thinned at 10 and 15 ppm at both FB and 14 days AFB. No firm recommendation can be given for NAA as a thinner of ‘Fuji’ at this stage.

This publication has 5 references indexed in Scilit: