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Disease Note

A Second Race of Meloidogyne chitwoodi Discovered in Washington State. G. S. Santo and J. N. Pinkerton, Washington State University, Irrigated Agriculture Research and Extension Center, Prosser, WA 99350. Plant Disease 69:361, 1985. Accepted for publication 25 January 1985. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-361g.

The Columbia root-knot nematode (Meloidogyne chitwoodi Golden et al.) is a serious pest on potato in the Pacific Northwest.  Alfalfa, which is commonly grown in rotation with potato, supports no or only slight nematode reproduction and is therefore considered a poor host for M. chitwoodi.  In 1982, however, following rotation with alfalfa, potato crops from two fields were damaged by M. chitwoodi.  Greenhouse studies show that this race of M. chitwoodi is capable of reproducing on alfalfa.  It produced an average of 23.3, 40.4, 29.3, 7.6, 6.6, and 2.2 egg masses per plant on alfalfa cultivars Ranger, Thor, Vernal, Washoe, Gladiator, and Nevada Syn XX, respectively.  The wild race reproduced only on Ranger (0.2 egg mass per plant).

References: O'Bannon, J. H., et al. Plant Dis. 66:1045, 1982.  Santo, G. S., et al. Plant Dis. 64:951, 1980.