Role of apple leafcurling midge in the spread of fire blight

Abstract

The incidence of apple leafcurling midge ( Dasineura mali) (ALCM) infestations in association with fire blight ( Erwinia amylovora) was monitored in Waikato, New Zealand during the 1997-98 season. In two blocks of apple cv. Malling-Merton MM106 rootstocks, increased fire blight incidence coincided with severe outbreaks of ALCM. Rain did not occur prior to severe outbreaks of both pests. Trees with no ALCM infestation did not develop fire blight, while 61.7% of those with ALCM infestation subsequently developed fire blight. ALCM damage to leaves predisposed them to fire blight infection. These findings provide the first quantitative evidence that ALCM may be involved in the spread of fire blight.