Control of Pineapple Heart Rot, Caused by Phytophthora parasitica and P. cinnamomi, with Metalaxyl, Fosetyl Al, and Phosphorous Acid. K. G. Rohrbach, Plant Pathologist, University of Hawaii, Honolulu 98622. S. Schenck, Plant Pathologist, Castle and Cooke Foods, P.O. Box 490, Wahiawa, HI 96786. Plant Dis. 69:320-323. Accepted for publication 20 October 1984. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-320.

Metalaxyl and fosetyl Al controlled pineapple heart rot, caused by Phytophthora parasitica and P. cinnamomi, and root rot, caused by P. cinnamomi. Preplant seed material dips with metalaxyl at 600 ppm and fosetyl Al at 1,200 ppm resulted in significant control. Phosphorous acid, a hydrolysis product of fosetyl Al, at 3.36–6.72 kg/ha resulted in significant heart rot control and increased plant growth because of root rot control. In greenhouse studies, downward translocation of both fosetyl Al and phosphorous acid occurred within 24 hr and resulted in root rot control.