Submitted to: Pulse Pipeline
Publication Type: Popular Publication
Publication Acceptance Date: 7/10/2013
Publication Date: 7/12/2013
Citation: Chen, W. 2013. Disease Alert: Stemphylium Blight. Pulse Pipeline. XIII:4.
Interpretive Summary: Stemphylium blight emerged to be a disease problem of lentil in the Pacific Northwest due to high susceptibility of a recently released lentil cultivar ‘Morena’. Because Stemphylium blight is a devastating disease of lentil in Bangladesh and India, we are closely monitoring the occurrence and progress of this disease in the Palouse region (eastern Washington and Northern Idaho). The disease was found on July 8, 2013 in lentil fields near the border between Washington and Idaho. The fields were planted with the susceptible lentil cultivar ‘Morena’. This article serves as an alert to growers of ‘Morena’ lentils, and provides instructions on how to identify the disease.
Technical Abstract: Lentil leaves showing symptoms of Stemphylium blight were collected from a lentil field northeast of Garfield (near Idaho border) on July 8, 2013, and incubation of the diseased leaves showed typical spores of the pathogen Stemphylium botryosum or other Stemphylium sp. The field was planted with ‘Morena’ lentil, a variety known to be susceptible to Stemphylium blight (it should be noted that ‘Morena’ has better tolerance to Rhizoctonia root rot than other lentil varieties). The disease starts only on individual leaflets (NOT on the stems) under lush canopy. The crop could look fine and healthy from above the canopy. You have to look carefully in the middle section of the plant under the canopy for initial signs of the disease. Tan or brown discoloration starts at the edge of the leaflets, and the whole affected leaflets may turn tan or brown, but the adjacent leaflets would look unaffected and healthy. If the whole plant turns yellow, that is likely due to a problem from the root system, and is not a sign of Stemphylium blight. Although Stemphylium blight has been known as a devastating disease of lentil in Bangladesh and India, and has been frequently observed in Canada and more recently in North Dakota, the disease was new to this region last year (2012). Its direct impact on lentil yield in this region is still unknown and efficient management practices are still to be developed.