Persistence of triazole growth retardants on stem elongation of Rhododendron and Kalmia

摘要: Triazole growth retardant chemicals may inhibit stem elongation of woody ornamental species for several years after application. Potted plants large-leaf Rhododendron catawbiense and Kalmia latifolia were treated with a single spray application paclobutrazol or uniconazole in the 2nd year from propagation. They transplanted into field next spring. The stems was measured 2–4 years. Treatments wide range doses applied 1991, 1992, 1995. For all except most dilute applications, retarded At highest doses, inhibited 2 results fit to model regulator action which assumed that inversely related amount applied. paclobutrazol, dose per plant half as much saturating tenfold uniconazole, about 0.5 0.05 mg, respectively. both chemicals, dose-response coefficient decreased exponentially time application, an exponential constant year−1. A reduced by immediately would only 12% year. However, greater result less than untreated