Lentil Disease Diagnostic Series: Powdery Mildew

Authors: Porter, Lyndon; Chen, Weidong

Submitted to: Extension Reports
Publication Type: Experiment Station
Publication Acceptance Date: 1/8/2019
Publication Date: 2/1/2019
Citation: Porter, L.D., Chen, W. 2019. Lentil Disease Diagnostic Series: Powdery Mildew. Extension Reports. PP1913.

Interpretive Summary: A short and concise disease diagnostic card was developed to help growers rapidly diagnose powdery mildew on lentil through descriptions and color photographs of symptoms commonly associated with the disease. The card also provides important factors that favor disease, facts regarding how to manage the disease, and a disease that could potentially be mistaken for powdery mildew.

Technical Abstract: Powdery mildew caused by Erysiphe pisi or Leveillula taurica can be a serious disease of lentils. The following symptoms typically are associated with powdery mildew: 1) white powdery spots that over time completely cover the leaf surface, 2) white mycelium that can appear felt-like or as paint on leaf surfaces, 3) infections can be more intense and common around flowering and late season, and 4) infected leaves can become chlorotic/necrotic and curled. Factors favoring disease development include: late plantings, conditions that limit sunlight, and temperatures between 59 to 77F. Important facts about powdery mildew are: 1) the pathogen can be soil-borne, seed-borne and wind-dispersed, 2) there are highly effective foliar fungicides available for management purposes, including elemental sulfur, 3) crop rotation with other non-legume crops is important, 4) lentil cultivars differ in their tolerance/resistance to the pathogen, and 5) powdery mildew can be potentially confused with white mold, which produces white fluffy mycelium on lower canopy under humid conditions.