Estimated economic impact of fire blight on long-term orchard economic performance with susceptible and resistant rootstocks

Abstract

We estimated the economic impact of theoretical fire blight induced tree loss using data from two long-term field trials in NY State. An economic analysis of profitability using Net Present Value (NPV) was conducted with three cultivars, eleven rootstocks and four planting systems. The impact of fire blight was modeled in terms of both the severity of the disease and the year of infection. We considered a range of scenarios with different infection rates (10 %, 50 %, 80 % and 100 %) of all the trees planted and different timings when the infection took place including the 1st year (prior to production), 5th year, 10th year and the 15th year during the life cycle of an orchard. The analysis showed that the smallest impact of fire blight induced losses on lifetime NPV occurred when the fire blight infection and tree death occurred in year 1 and was greatest when infection and tree death occurred in year 10. If the infection occurred in year 15 then the losses in NPV were less. As expected, the analysis showed that a low percentage of tree loss due to fire blight at any given year of the orchard life resulted in a low impact on lifetime NPV while greater levels of infection and tree loss were associated with higher losses in NPV. The use of fire blight resistant rootstocks dramatically reduced the negative impact of fire blight induced tree losses on NPV. With susceptible rootstocks (M.9 and M.26), the reduction in NPV with high levels of tree infection was as high as 70 % which would render the planting unprofitable, while with resistant rootstocks the losses in NPV were lower (<30 %) and the orchard would still be profitable. High-density orchard systems like the Tall Spindle system had less sensitivity to fire blight induced losses than lower density systems. Cultivar also had an important effect on the level of fire blight induced losses of NPV. With a high priced cultivar like ‘Honeycrisp’ the percentage loss in NPV was less than with the lower priced cultivars like ‘Fuji’ and ‘Gala’.