Fire blight is the most economically important disease of apples in Kentucky. It is estimated that 50-80% of the 962 acres of apple in Kentucky may be infected with the disease each year. Risk for infection varies from year to year and orchard to orchard as it is dependent on weather conditions. Growers in Kentucky must be diligent in chemical application to prevent fire blight bacteria from infecting trees. Historically growers have made applications every 5-7 days without consideration for risk of infection. This practice can result in unnecessary sprays, which adds to production costs, or mistimed applications, which can reduce yield. 

As a way to aid growers in assessing the risk for fire blight, the Department of Plant Pathology Fruit Specialist partnered with University of Kentucky Agriculture Weather to develop the Fire Blight Disease Prediction Model. Growers can assess local risk by selecting their county and orchard history. Use of the Fire Blight Disease Prediction Model was promoted at grower meetings and via fire blight alert articles in Kentucky Pest News during apple tree bloom in the spring of 2016. During March and April of 2016 (when trees were susceptible to infection) the predictive model website was visited 24,567 times, with 26% being from first time visitors.  

Growers were trained in use of the prediction model in 2014 through 2016. They were surveyed in the late summer of 2016 to determine the impact of the disease prediction model in their own farms. Twenty two growers participated in the survey. The fire blight model was used by 95% of growers, and respondents indicated an average of 5 antibiotic sprays per season. As a result of using the model, 83% of growers adjusted their spray program, which resulted in 67% of growers obtaining better control compared to calendar-based sprays and 28% obtaining similar control to calendar-based sprays. A decrease of an average of 1.5 applications was reported by 41% of growers. This change in practices saved growers between $14,850 and $24,750 in product costs. An additional 59% of growers reported an increase of an average of 2 applications. While these growers would increase their input costs by an estimated $28,291-$47,152, this additional expense is offset by the additional fire blight control that was achieved. Some experts suggest that the labor involved to remove infected plant material is valued at $1,000/acre and that tree loss from fire blight could be as high as $2,000 per acre. Thus, growers that utilized additional sprays saved $1,414,564 through reduced labor costs and tree losses. The Fire Blight Disease Prediction Model will continue to improve grower practices and reduce grower cost or losses as all growers indicated that they would use the model in the future.