Main content area

Acylcyclohexanediones and biological control agents: combining complementary modes of action to control fire blight

Spinelli, Francesco, Vanneste, Joel L., Costa, Guglielmo
Trees 2012 v.26 no.1 pp. 247-257
Erwinia amylovora, Pantoea agglomerans, apples, bacteria, biological control agents, blight, epiphytes, flowers, leaves, nectar, nutrients, orchards, pathogens, pears, shoots, synergism
Acylcyclohexanediones and antagonistic bacteria sprayed alone or in combination have been shown to suppress fire blight of apple and pear. Acylcyclohexanediones, such as prohexadione-calcium and trinexapac-ethyl, increase plant resistance and are effective against the shoot blight phase of the disease. Antagonistic bacteria, such as Pantoea agglomerans, compete with the pathogen (Erwinia amylovora) for space and nutrients on stigmas, which prevents blossom blight. Potential synergistic effects of acylcyclohexanediones with P. agglomerans for fire blight suppression were investigated on leaves and flowers of apple and pear. Acylcyclohexanediones modified the composition of apple nectar and stigmatic secretions, which resulted in moderately higher epiphytic populations of P. agglomerans strain P10c. In experiments in apple orchards, the combination of acylcyclohexanediones and P. agglomerans gave the greatest protection against blossom blight and shoot blight. In pear orchards, under natural infection conditions, a similar result was obtained for the 3 of the 4 years of the experiment.