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The Role of Pratylenchus penetrans in the Root Rot Complex of Canning Pea. Peter O. Oyekan, Research Assistant, Department of Plant Pathology, University of Wisconsin, Madison 53706, Present address of senior author: Ministry of Agriculture and Natural Resources, Western Nigeria, Ibadan, Nigeria; J. E. Mitchell, Professor, Department of Plant Pathology, University of Wisconsin, Madison 53706. Phytopathology 62:369-373. Accepted for publication 27 October 1971. DOI: 10.1094/Phyto-62-369.

The effect of Pratylenchus penetrans on root rot of canning pea caused by Aphanomyces euteiches was determined in untreated silt loam and sandy loam soils and in soils pasteurized with aerated steam at 60 C for 30 min. Pratylenchus penetrans increased the severity of root rot in the two soils, but the effect of the nematode was most striking in the untreated silt loam soil with a threshold level of 25 oospores/g soil and with a water potential between -1/3 and -1 bar. The effect of the nematode was reduced in soils treated with aerated steam or in soils with a higher level of inoculum of A. euteiches, as disease due to the latter organism alone was severe under these conditions.