Flower Thinning of Peach with Desiccating Chemicals

Abstract

Abstract Airblast applications of ammonium nitrate, ammonium thiosulfate, an oxylated alcohol surfactant (SN-50), or 7-oxabicyclo-(2,2,1) heptane-2,3-dicarboxylic acid (endothall) to peaches [Prunus persica (L.) Batsch] in bloom reduced fruit set and increased fruit size on several cultivars. Foliage injury was minimal when applied at bloom. Applications of these chemicals 6 days post-bloom to ‘Redhaven’ trees caused unacceptable foliage injury and did not cause fruit abscission. Several other surfactants and fertilizers were found to have caustic action in laboratory trials, but fruit set on ‘Redhaven’ was not reduced in field airblast trials.