Submitted to: Plant Disease
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/26/2008
Publication Date: 6/1/2008
Citation: Riga, E., Porter, L.D., Mojtahedi, H., and Brocke, G.F. 2008. First report of Pratylenchus neglectus, Pratylenchus thornei and Paratylenchus hametus nematodes causing yield reduction to dry land peas and lentils in Idaho. Plant Disease 92: 979. Interpretive Summary: Nematodes are small worm-like organisms that can be parasitic on many agricultural crops resulting in reduced productivity. Nematodes were not considered a problem in dry land pea and lentil production areas of the Pacific Northwest until the present report. In 2006, large, stunted, yellow patches of both pea and lentil plants were observed in several locations in Idaho, resulting in significant yield losses ranging from 40 to 100%. Pin and lesion nematodes were associated with the yield losses in the fields, and there negative impacts on pea and lentil were verified in greenhouse tests. There have been no previous reports in Idaho and the surrounding states on the effect of plant parasitic nematodes on dry land peas and lentils, but this report acknowledges a major nematode issue and management strategies needs to be developed to control this newly emerging production problem.
Technical Abstract: In June 2006, stunted, chlorotic, plants in large patches were observed in two 100-acre fields of dry land peas (Pisum sativum) in Latah County Idaho which resulted in 90% and 75% crop loss. In the same region a 300 acre field of dry land lentils (Lens culinaris) also had plants showing poor growth, wilting and yellowing in large patches which resulted in 40% crop loss. The three plant pathogenic nematodes associated with yield loss were two lesion nematodes (Pratylenchus neglectus and P. thornei) and one pin nematode (Paratylenchus hametus). A subsequent small field survey showed that seven dry land pea fields, under Columbian cultivar, in Latah and Nez Perce Counties, ID and one dry land pea field, under Small Sieve cultivar, in Latah County, ID, had means of 551 and 2,178 lesion nematodes per 1 g of dry root, respectively. Twelve lentil fields in Latah County, six planted with the Red Chief cultivar, and six with the Pardina cultivar, had means of 279 and 987 lesion nematodes per 1 of g dry root and 628 and 671 pin nematodes per 250 cm3 soil, for each cultivar respectively. Mixed populations of both lesion species and pin nematode species were found in the field samples. Pathogenicity tests on lentils or peas included either soil from the infested fields or nematodes extracted from the roots or soil from the rhizosphere of corresponding plants at 2 nematodes per g soil. Pin nematodes were extracted from the soil using a Baerman pan method (1) while lesion nematodes were detected inside the roots by staining the roots with acid fuchsin (2). The greenhouse assays verified the negative impact of these nematodes on plant growth of dry land lentils and peas. There has been no report in Idaho and the surrounding states on the effect of plant parasitic nematodes on dry land legumes.