Purple Stain of Carica papaya. M. N. Nelson, Department of Plant Pathology, University of Hawaii, Honolulu 96822. A. M. Alvarez, Graduate Student and Assistant Plant Pathologist, Department of Plant Pathology, University of Hawaii, Honolulu 96822. Plant Dis. 64:93-95. Accepted for publication 9 March 1979. Copyright 1980 American Phytopathological Society. DOI: 10.1094/PD-64-93.

A new strain of Erwinia herbicola, which produces an extracellular, water-soluble, purple pigment in culture, is the causal agent of purple-stain disease of papaya (Carica papaya) in Hawaii. Disease incidence was highest during January and February, when the pathogen was readily recovered from symptomless as well as purple-stained fruits. In vitro pigment production was greatest when bacteria were grown in liquid shake culture containing 0.5% sucrose and 1% peptone and buffered at pH 5.5 or lower. The pigment has absorbance peaks at 595, 575, and 580 nm in water, ethanol, and pyridine, respectively.