D.I. Breth, H.S. Aldwinckle
Predicting blossom blight is the most critical control strategy in controlling fire blight in apples and pears. There are several models and forecasting systems available to make this prediction for growers, including MARYBLYT™ and Cougarblight. Weather data were collected from sensors in western New York state to measure the maximum and minimum temperature and wetting periods. Blossom blight “risk” predictions by MARYBLYT™ (version 4.3) and Cougarblight were compared in 1998-2001. MARYBLYT™ uses the epiphytic inoculum potential (EIP) based on 110 accumulated degree hours above 18.3oC during bloom, a wetting event, and an average temperature of 15.6oC the day of the infection. Cougarblight uses accumulated heat units, and adjustable thresholds based on history of fire blight in or near the orchard. Using the eyes of the consultants who scout commercial orchards, blossom blight symptoms were documented in orchards where streptomycin applications were not made when infections were predicted. The two models correlated well when comparing accumulated heat units associated with wetting events. Either model can be used in New York State for growers to time streptomycin applications to provide good control of blossom blight and limit applications most seasons to 1-2 during bloom.
Breth, D.I. and Aldwinckle, H.S. (2002). COMPARISON OF MODELS FOR BLOSSOM BLIGHT PREDICTION IN NEW YORK. Acta Hortic. 590, 147-151
DOI: 10.17660/ActaHortic.2002.590.20
Erwinia amylovora, Malus, MARYBLYTTM, Cougarblight

Acta Horticulturae