Role of Wind-Driven Rain, Aerosols, and Contaminated Budwood in Incidence and Spatial Pattern of Fire Blight in an Apple Nursery

The role of wind-driven rain, rain-generated aerosols, and Erwinia amylovora contaminated budwood in the epidemiology of fire blight in a Michigan apple (Malus × domestica) nursery was investigated in 1992 and 1993 and in a simulated nursery planting at Michigan State University (MSU) in 1993. A degree-day model, MARYBLYT, was used to assess whether fire blight outbreaks were associated with storms containing wind-driven rain. Most outbreaks, especially those occurring early in the season, were associated with previous storms. Spatial lag autocorrelation analysis indicated that when fire blight was initially detected in the nursery each season, significant autocorrelations among spatial lags generally were within-row or formed tight clusters