<i>In vitro</i> evaluation of fungal isolates and nutrient amendments for enhancing apple leaf decay

Abstract

Primary spread of apple black spot is by ascospores produced from overwintering apple leaf litter To find effective degraders of litter an in vitro trial screened 59 fungal isolates for the ability to colonise sterilised senesced apple leaf discs The isolates of Aureobasidium Alternaria Chaetomium Coniothyrium Epicoccum Fusarium Phoma Trichoderma and Ulocladium spp had originated from the phylloplane or leaf litter of fruit crops The whiterot basidiomycete isolates were from fruiting bodies on native beech poplar and fruit trees The 18 isolates that colonised leaf discs most rapidly were further tested with five nutrient leaf amendments for their biodegradation activity on leaf discs After incubation at 10C for 9 weeks the most effective isolates of Trametes versicolor Phoma Epicoccum and Chaetomium spp caused 54 39 37 and 23 weight reduction respectively while the leaf amendments urea and the mixture of Mycorrcintrade; and Digestertrade; caused 29 and 20 reduction respectively These treatments were selected for evaluation in a field trial