Evaluation of Crucifer Green Manures for Controlling Aphanomyces Root Rot of Peas. A. M. Muehlchen, Research Specialist, Department of Plant Pathology, University of Wisconsin-Madison 53706. R. E. Rand, and J. L. Parke. Senior Research Specialist, and Associate Professor, Department of Plant Pathology, University of Wisconsin-Madison 53706. Plant Dis. 74:651-654. Accepted for publication 3 January 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0651.

Several different species of crucifers were tested as soil amendments for the control of Aphanomyces root rot of peas. In a 2-yr field study, crucifers were planted the first year as full season crops or as fall cover crops following peas. The crucifers were incorporated as green manures. The following spring, peas were planted in all the plots, and stand counts and fresh pea yields were determined. Significant treatment effects on stand loss were found. Average yields were not significantly different. A fall crop of white mustard (Sinapis alba L.) following peas appeared most promising and was chosen for further study. In subsequent field studies, a fall crop of white mustard significantly reduced root rot severity ratings of pea plants grown the following year. After two successive cycles of peas followed by white mustard, an increase in pea yield and a decrease in root rot severity were observed. In a growth chamber bioassay, white mustard amendment reduced the number of infective propagules of Aphanomyces euteiches Drechs. in infested soil.