A Degree Day Model for Predicting the Emergence of Swamp Dodder in Cranberry

A simple model that predicts the onset of swamp dodder ( Cuscuta gronovii Willd. ex R. & S. # CVCGR) emergence was developed. The use of growing degree days (GDD) with low-temperature thresholds (LTT) of 3.3° or 0°C had a better fit as a predictor for the beginning of emergence than either air temperature or soil temperature at a depth of 30 mm alone. This model can be used to time preemergence herbicide applications to coincide with the period of maximum dodder sensitivity, thereby increasing herbicide efficacy.