Application of Antitranspirant and Reduced Rate Fungicide Combinations for Fruit Rot Management in Cranberries. H. A. Sandier, Cranberry IPM Specialist, Cranberry Experiment Station, P.O. Box 569, East Wareham, Mass. 02538. Plant Dis. 79:956-961. Accepted for publication 16 June 1995. Copyright 1995 The American Phylopathological Society. DOI: 10.1094/PD-79-0956.

Studies were conducted over a 3-year period to evaluate the efficacy of reduced rate combinations of chlorothalonil and an antitranspirant (AT), Wilt-Pruf, for control of fruit rot in cranberries. Several reduced rate combinations provided control comparable to that with the fungicide used alone at suggested label rates of 0.76 to 1.34 liters/ha (4 to 7 pt/A) in field trials. In two trials, higher concentrations of the AT (3 to 5%) had a detrimental effect on total and usable yield at higher fungicide rates. The lowest rate of chlorothalonil that can be effectively used in combination with any tested rate of Wilt-Pruf is 0.76 liters/ha (4 pt/A). Using 0 or 0.38 liters/ha (0 or 2 pt/A) with any tested rate of the AT inadequately protected the berries against fruit rot infection. The incorporation of reduced rate combinations may offer the management advantage of lowered environmental risk per fungicide application in certain situations.

Keyword(s): Coleophoma empetri, Glomerella cingulata, Codronia cassandrae, integrated pest management, Phomopsis vaccinii, Phyllosticta vaccinii, Physalospora vaccinii, spray adjuvants, Vaccinium macrocarpon