PROHEXADIONE-CALCIUM, A GIBBERELLIN BIOSYNTHESIS INHIBITOR, CAN REDUCE VEGETATIVE GROWTH IN 'BING' SWEET CHERRY TREES

Prohexadione-Ca (P-Ca, BAS 125 11 W), a gibberellin biosynthesis inhibitor, was applied to mature, vigorous `Bing’ cherry trees at 3 concentrations (75, 150 or 300 mg a.i./L). Treatments were applied by whole-tree sprays in the autumn (postharvest), with or without a follow-up treatment during the subsequent spring (preharvest) or autumn (one year later), with an untreated control. There were no effects of autumn-applied treatments on reduction of vegetative growth in either the season of application or the next year. Spring-applied P-Ca treatments significantly reduced vegetative growth as measured by shoot length. The reduction in shoot length, both in lateral and terminal positions, was proportional to the dosage applied. Further work is required to formulate definitive recommendations for Chilean conditions, as no measurements on fruit quality were conducted; however, this bioregulator appears promising for in achieving growth control under vigorous conditions typical of Chilean cherry orchards.