SUPPRESSION OF BOTRYTIS BLIGHT IN CUT ROSE FLOWERS WITH GIBBERELLIC-ACID - EFFECTS OF EXOGENOUS APPLICATION OF ABSCISIC-ACID AND PACLOBUTRAZOL

The postharvest development of Botrytis blight in rose flowers (Rosa x hybrida cv. Mercedes) was suppressed when flower buds were sprayed wi th 1 mM solution of gibberellic acid (GA(3)). The development of the d isease was promoted by application of abscisic acid (ABA) and the supp ressive effect of GA(3) was reduced when GA(3) solution was-supplement ed with ABA. The GA(3)-imposed suppression of Botrytis blight was enha nced by addition of paclobutrazol (PBZ) to the GA(3) solution, but the development of the disease was not affected by PBZ alone. Germination of conidia and germ-tube elongation of Botrytis cinerea in vitro were unaffected by ABA and PBZ, whereas linear growth of fungal colonies w as promoted by ABA but was inhibited by PBZ.