A yellow stripe on the leaf sheath and basal portion of the leaf blade is common. Later, the stripe may extend the entire length of the leaf and the leaf may die. At heading, diseased plants are often stunted and appear a light tan color in contrast to the larger, green healthy plants. Spikes may be deformed or may fail to emerge. At heading, spores are produced on diseased leaves and spread by wind to nearby heads.
Grain produced by diseased plants is typically brown and shriveled.
Drechslera graminea survives entirely as mycelium in the outer layers of the seed. When the seed germinates in moderately moist soil at temperatures below 55 degrees F, the fungus mycelium penetrates and infects the seedling. The fungus grows within plant tissue and occupies the actively growing plant parts. Net blotch and spot blotch, common diseases of barley, are caused by the fungi, Drechslera teres and Bipolaris sorokineana , respectively. Net blotch is most common during rainy and humid weather, and early flag leaf infections can result in both reduced grain yield and weight.