Bacterial Spot, Apple Scab, Cedar Apple Rust and Cherry Leaf Spot Infection Periods

Posted: June 3, 2011

Warm temperatures (70-85 degrees F) with light rains, heavy dew, and windy weather are most conducive for bacterial spot (Xanthomonas pruni) development and spread in stone fruit. Infections occur only when the leaves are wet, and the amount of disease increases exponentially. Bacterial spot infection periods in the graph were determined using a Spectrum Weather Monitoring System and Ohio State University Bacterial Spot of Stone Fruit model, HYG-3019-95. Graphs for apple scab, cedar apple rust, and cherry leaf spot infection periods are attached. Primary scab is still active but declining.