A sooty blotch flyspeck (SBFS) warning system, developed in North Carolina and modified in Kentucky, extends the period between first-cover and second-cover fungicide sprays until a total of 175 hours of wetness has been measured in the orchard canopy. After second cover,sprays are made at 2-week intervals until harvest. In our replicated field experiments, the warning system was consistently as effective as calendar based spray timing in suppressing SBFS and other summer diseases (secondary scab and fruit rots). But in our demonstration trials in commercial orchards, the warning system resulted in commercially unacceptable levels of SBFS in 12 of 28 site-years.
Iowa State University
Jesse, Laura C.H. and Gleason, Mark L., "Putting a Sooty Blotch-Flyspeck Warning System into Practice" (2007). Iowa State Research Farm Progress Reports. 871.