Management Decisions at Planting Can Affect Small Grain Diseases

Nathan Kleczewski, Extension Specialist – Plant Pathology;

Aside from the rain we received, it has been very hot and dry, allowing corn to dry down and be harvested early in many areas. Even though it may be tempting, it is best to wait until after the Hessian fly free date for your county. Planting after this data can reduce potential for insect issues as well as several diseases.

  1. Barley Yellow Dwarf (BYD), although historically not a significant issue in our area, is a virus spread by several common species of aphids. The earlier small grains are planted, the more potential exposure to virus-carrying aphids and potential for early season BYD infections, which are often associated with significant yield loss (Figure 1).
    Figure 1. Fall barley yellow dwarf infections are often associated with tissue discoloration and stunting, which can result in patches of stunted plants throughout the field. Image obtained from accessed 9/10/15
  2. Powdery mildew is caused by a fungal pathogen that requires a living host to grow and reproduce. Early planted small grains are at a higher risk for fall infections by powdery mildew. Fall infections can reduce tiller production and also serve as local sources of inoculum in the spring. Avoiding early planting can minimize the risk of early season infections and potential issues with powdery mildew early next spring.
  1. Similarly, avoiding early planting can minimize potential issues with leaf blotch pathogens, such as Stagonospora leaf and glume blotch and tan spot in wheat. These residue-borne pathogens do not require a living host to grow and reproduce, but can infect crops early and reduce yields in some instances.

Lastly, cultivar selection is key to managing commonly occurring diseases in wheat and barley. If you are committed to planting early, ensure that your cultivars are rated for good to excellent resistance to leaf blotch and powdery mildew. Information on disease resistance to cultivars grown in our area can be found at the University of Delaware Cooperative Extension Website. The Virginia Tech 2015 wheat data can be found here: Virginia Tech also has excellent 2 and 3 year data summaries on Powdery mildew resistance and Fusarium Head Blight reaction that can be found here: Remember to focus on the cultivar ranking in terms of DON when considering reactions for Fusarium Head Blight.