Development of Aspergillus Molds in Litter from Pistachio Trees. M. A. DOSTER, Department of Plant Pathology, University of California, Davis, Kearney Agricultural Center, 9240 S. Riverbend Ave, Parlier 93648. T. J. MICHAILIDES, Department of Plant Pathology, University of California, Davis, Kearney Agricultural Center, 9240 S. Riverbend Ave, Parlier 93648. Plant Dis. 78:393-397. Accepted for publication 8 January 1994. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/PD-78-0393.

Aspergillus molds frequently infested, infected, and sporulated on pistachio litter such as fallen pistachio fruit and male inflorescences throughout summer in commercial pistachio orchards in California. A. niger was isolated much more frequently from pistachio litter than any other species, but the aflatoxin producers, A. flavus and A. parasiticus, also developed in pistachio litter. Two distinct strains of A. flavus were isolated: strain L (a few large sclerotia) and strain S (abundant small sclerotia). Strain L occurred substantially more often than strain S. All isolates of strain S and A. parasiticus were aflatoxin producers, but only 43% of the isolates of strain L produced aflatoxins. Other species isolated in the subgenus Circumdati were A. tamarii, A. melleus. A. ochraceus, A. japonicus, and A. wentii. The development of Aspergillus molds in pistachio litter could increase the amount of Aspergillus inoculum in the orchard, resulting in greater numbers of moldy and mycotoxin-contaminated pistachio nuts.

Keyword(s): debris, ochratoxin, Pistacia vera