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Occurrence of Meloidogyne chitwoodi in Potato Fields in Colorado. J. N. Pinkerton, Department of Plant Pathology, and Weed Science, Colorado State University, Fort Collins 80523. G. A. McIntyre, Department of Plant Pathology and Weed Science, Colorado State University, Fort Collins 80523. Plant Dis. 71:192. Accepted for publication 20 November 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0192D.

Meloidogyne chitwoodi (Golden et all, the predominant root-knot nematode species in potato (Solanum tuberosum L.) production areas of the northwestern United States, can severely reduce yield and tuber quality, making the crop unmarketable (2). In 1983, 2,150 ha were surveyed for phytonematodes in the San Luis Valley, Colorado. M. chitwoodi was detected in 16% of the fields sampled. This is the first report of M. chitwoodi in Colorado. Its distribution throughout the surveyed area in fields with different grower and cropping histories suggests that it is not a recent introduction. Densities of second-stage juveniles were low at harvest 20/500 cm3 of soil). Light tuber symptoms were observed in only one field. Cool soil temperatures in this 2,400-m elevation valley appear to limit M. chitwoodi to one generation per year (I). These data suggest that the impact of M. chitwoodi on fresh market potato production in the San Luis Valley may be negligible. This is supported by 1984 and 1985 shipping inspections involving over 48,000 individual shipments, only 0.0001% of which contained symptomatic tubers.

References: (1) G. D. Griffin. J. Nematol. 17:395,1985. (2) A. P. Nyczepiret al. J. Nematol. 14:347, 1982.