Bill Cissel, Extension Agent – Integrated Pest Management, University of Delaware; bcissel@udel.edu
Congratulations to Buzz Lowe for correctly identifying the disease in the photo as Stagonospora nodorum leaf blight and glume blotch and for being selected to be entered into the end of season raffle for $100 not once but five times. Everyone else who guessed correctly will also have their name entered into the raffle. Click on the Guess the Pest logo to participate in this week’s Guess the Pest challenge!
Stagonospora nodorum Leaf Blight and Glume Blotch
By Nancy Gregory
Stagonospora nodorum leaf blight and glume blotch can cause yield loss on wheat, especially if infection occurs before grain fill. Stagonospora overwinters in crop residue and can be spread in infected seed. Disease is favored by environmental conditions of high moisture and wind, resulting in spore movement up through the canopy. Disease spread slows when weather turns dry. Symptoms include oval to round, brown leaf spots with yellow halos. The glume blotch phase is characterized by gray to purple brown discoloration on the outer seed coverings. Closer look with a hand lens may show a dusty cast to the heads when the fungus is producing spores. Management strategies include rotation to soybean, corn, or other on-hosts, as well as proper plant density to avoid over-crowding. Fungicide applications of a labeled triazole or strobilurin product at heading can be a part of a management plan. Resistant varieties are available for fields with a known history of glume blotch.
