Use of environmental parameters and immunoassays to predict Rhizoctonia blight and schedule fungicide applications on creeping bentgrass

Abstract

Rhizoctonia blight, commonly called brown patch, is an important disease of turfgrass, particularly creeping bentgrass ( Agrostis palustris) maintained as putting greens and tees. Because the disease is often intermittent, three forecasting systems were evaluated for their ability to reduce fungicide applications without development of unacceptable levels of disease damage. Environment-based (EB) forecasts were based on environmental parameters associated with disease development in Massachusetts. Immunoassay-based (IB) forecasts were based on reflectance unit thresholds using pathogen immunoassay field kits. A combination system that utilized both EB and IB forecasts was also evaluated. The impact of forecasting systems on fungicide efficacy and number of fungicide applications in comparison to calendar application schedules was examined for two growing seasons in Massachusetts, New Jersey, and Georgia. Each system provided an acceptable level of disease control and reduced fungicide applications compared with calendar application schedules. The forecasts offer a means to record and justify fungicide application decisions in integrated pest management programmes.