Cause and Control of Crown Rot of New Guinea Impatiens. Sabrina Castillo, 10a Calle Z-66, Zona 14, Guatemala City, Guatemala. J. L. Peterson, Department of Plant Pathology, Rutgers University, New Brunswick, NJ 08903. Plant Dis. 74:77-79. Accepted for publication 26 August 1989. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0077.

Pythium ultimum and Rhizoctonia solani AG-4 each caused a similar crown rot of New Guinea impatiens growing in commercial greenhouses in New Jersey. P. ultimum caused a black moist rot while R. solani caused a drier brown rot and cracking of the infected tissue. The fungi were isolated from the crown of various diseased plants but not generally from stem sections above the crown. New Guinea impatiens cultivars showed a range of susceptibility to the disease caused by each organism. The cultivar Milky Way was most resistant and cultivars Aurora, Cosmos, and Twilight were the most susceptible to both fungi among the cultivars tested. PCNB controlled the Rhizoctonia-induced disease and metalaxyl and fosetyl-Al controlled the Pythium-induced disease.