Nitrogen Source Corrects a Potato-Dextrose Agar Medium Deficient in Supporting Mycelial Growth of Monilinia spp.. P. L. Sholberg, Research Assistant, Department of Plant Pathology, University of California, Davis 95616. J. M. Ogawa, Professor, Department of Plant Pathology, and T. S. Inouye, Research Associate, Department of Soil and Water Science, University of California, Davis 95616. Plant Dis. 65:649-651. Accepted for publication 5 December 1980. Copyright 1981 American Phytopathological Society. DOI: 10.1094/PD-65-649.

Mycelial growth of Monilinia spp. was compared on one freshly prepared and two commercial potato-dextrose agars. Growth on the agar made by BioQuest was found to be atypical. Addition of various ingredients to this agar indicated a deficiency in the amount of nitrogen needed for typical mycelial growth of the fungi. Subsequent analysis of the three potato-dextrose agars showed that the one made by BioQuest contained the least nitrogen. When an organic source of nitrogen was added to it, typical mycelial growth of M. laxa and M. fructicola was restored.

Keyword(s): brown rot.