Shaul, O., Department of Plant Pathology, ARO, Volcani Center, Bet Dagan 50250, Israel, Kennedy-Leigh Center for Horticultural Research, Hebrew University of Jerusalem, Faculty of Agriculture, P.O. Box 12, Rehovot 76100, Israel
Elad, Y., Department of Plant Pathology, ARO, Volcani Center, Bet Dagan 50250, Israel
Zieslin, N., Kennedy-Leigh Center for Horticultural Research, Hebrew University of Jerusalem, Faculty of Agriculture, P.O. Box 12, Rehovot 76100, Israel

The postharvest development of Botrytis blight in rose flowers (Rosa x hybrida cv. Mercedes) was suppressed when flower buds were sprayed with 1 mM solution of gibberellic acid (GA3). The development of the disease was promoted by application of abscisic acid (ABA) and the suppressive effect of GA3 was reduced when GA3 solution was supplemented with ABA. The GA3-imposed suppression of Botrytis blight was enhanced by addition of paclobutrazol (PBZ) to the GA3 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 was promoted by ABA but was inhibited by PBZ. © 1996 Elsevier Science B.V. All rights reserved.