Disease Note

Aphanomyces euteiches on Pea in Ontario, Canada. J. C. Tu, Agriculture Canada Research Station, Harrow, Ontario N0R 1G0. Plant Disease 69:268, 1985. Accepted for publication 30 October 1984. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-268a.

Although Aphanomyces euteiches Drechs. is widespread and causes severe root rot of peas (Pisum sativum L.) in major pea-growing areas in the United States, the fungus has not been reported in Ontario, Canada.  In 1983, 58 of 782 isolations made from diseased plants in 33 pea fields in Essex and Kent counties, Ontario, were identified as A. euteiches.  Other fungi isolated included Fusarium solani (Mart.) Appel & Wr. (356), F. oxysporum Schlecht. ex Fr. (119), and Pythium spp. (48), as well as Rhizoctonia solani Kühn and occasionally Thielaviopsis basicola (Berk. & Br.) Ferraris.  The morphological characteristics of the Aphanomyces isolates were similar to those of a culture of A. euteiches obtained from J. M. Kraft of Prosser, Washington.  The oogonia ranged from 28.0 to 36.1 μm and the oospores from 17.6 to 23.3 μm in diameter.  Upon inoculation, the fungus caused a brownish black soft rot in the primary root and the lower part of the hypocotyl in pea, alfalfa, and bean; the fungus was reisolated from inoculated plants.  This is the first report of this fungus on pea in Ontario, Canada.

References: McKeen, W. E., and Traquair, J. A. Can. J. Plant Pathol. 2:42, 1980.  Zaumeyer, W. J.  U. S. Dep. Agric. Handb. 228, 1962.