Disease Note.

Pratylenchus neglectus on Dryland Wheat in Washington. H. Mojtahedi, Irrigated Agriculture Research and Extension Center (IAREC), Washington State University. G. S. Santo, and J. M. Kraft. Irrigated Agriculture Research and Extension Center (IAREC), Washington State University, and USDA-ARS, IAREC, Prosser, WA 99350. Plant Dis. 76:323. Accepted for publication 1 October 1991. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-0323A.

In 1986, high numbers of Pratylenchus neglectus Filipjev & Schuurmans Stekhoven were extracted from roots of stunted dryland winter wheat (Triticum aestivum L. 'Stephens,) near Walla Walla, Washington. The wheat isolate of P. neglectus was increased on excised roots of corn (Zea mays L. 'Pioneer 3732') in Gamborg's B-5 medium. Six inoculum levels (0, 625, 1,250, 2,500, 5,000, and 10,000 nematodes per pot) were added around Stephens seeds sown in 600 cm³ fumigated (methyl bromide) loamy sand in pots. There were five replicates per level, and plants were harvested after 3 mo in the greenhouse at 18-22 C. The reproductive factors (final population ÷ initial population) ranged between five and 33. The number of nematodes per gram of fresh root was within the range observed in the field (88-2,870). Plant fresh weight (Y) was inversely related to initial inoculum levels (X): Y = 143.3 × X^-0.018, R2 = 0.4, P < 0.01. The low value of b (slope) indicated that P. neglectus was a relatively weak pathogen on Stephens under the test conditions. This is the first report of P. neglectus on wheat in the state of Washington.