Effect of prohexadionecalcium on nectar composition of pomaceous flowers and on bacterial growth

Abstract

Prohexadionecalcium is an acylcyclohexanedione that reduces incidence of fire blight caused by Erwinia amylovora To determine whether prohexadionecalcium can be used in conjunction with biological control agents its effect on the secretion and composition of nectar from apple and pear flowers was evaluated Plants treated with prohexadionecalcium produced more nectar but the sugar concentration of the nectar was lower The ability of E amylovora and of two biological control agents of fire blight Pantoea agglomerans and Pseudomonas fluorescens to grow in a sugar solution corresponding to the composition of nectar from treated or untreated plants was determined in the laboratory All bacteria including E amylovora grew better in the sugar solution corresponding to the nectar from treated plants The concentration of sugar in the nontreated flowers may be too high for bacterial growth These results also suggest that prohexadionecalcium can be used alongside biological control agents for reduction of fire blight incidence