Growth and Cropping of ‘Redhaven’ Peach Trees Following Foliar Applications of Flurprimidol and Paclobutrazol

Flurprimidol (FP) and paclobutrazol (PB) were applied foliarly to 5-year-old ‘Redhaven’ peach [Prunus persica (L. Batsch)] trees 3 weeks after full bloom, at 0, 500, 1000, 2000, and 3000 ppm. The 2 growth retardants generally affected growth similarly at any given concentration. Shoot growth was suppressed in a linear manner as concentration was increased for both materials the year of application. Only FP suppressed shoot growth the 2nd season following treatment, while both materials enhanced shoot growth the 3rd season following treatment. Both materials suppressed trunk growth for 2 seasons. Yield and fruit size were not significantly influenced by treatments. Yield efficiency was greatest for trees treated at the highest rates of both materials 3 seasons after application. Vegetative and floral bud break on treated trees was advanced the 3rd season after application. Chemical names used: β-[(4-chlorophenyl)methy]-2-(l,l-dimethylethyl)-l-H,2,4-triazole-l-ethanol (paclobutrazol); α-(l-methylethyl)-α-[4-(trifluoromethoxy)phenyl]-5-pyrimidinemethanol (flurprimidol).