Using Top Grafting to Manage Endemic Fire blight Infection in Apple Trees at UVM Horticulture Research and Education Center

Fire blight, an infection that affects apple and pear trees, is caused by the bacteria Erwinia amylovora. It infects trees through any opening, natural or otherwise, and will spread throughout the vasculature of the tree if left untreated. Currently, the management techniques for control of fire blight consist of prevention through heavy sanitation, pruning, or application of sprays, which all are very time-consuming and / or costly endeavors. This study seeks to determine if top grafting, a method only previously used for propagation, decreasing the physiological age or changing of varieties of trees, is an effective and worthwhile option for control of fire blight, as top grafting involves the removal of most of the aboveground biomass. In this study we analyzed a previously untested hypothesis, as there is no published research on the effects of top grafting infected trees compared to common treatments, pruning and application of sprays. This paper outlines the first two years of the study, including disease and harvest data for the treatment groups, as well as a net present value analysis, which predicts what the treatments could look like up to 20 years in the future, comparing the replacement of tree mass through top grafting versus maintaining current conditions.