Helminthosporium leaf spot is the most common leaf spot of oats in North Carolina and is sometimes found on wheat, barley, and rye. Symptoms vary depending on the host and the particular Helminthosporium species causing the disease. The outer edges of the spots merge from brown to yellow or red and frequently spread over the greater part of an infected blade. Sometimes the disease does not produce well-defined spots but causes a leaf to look withered as if it has been injured by adverse weather. Lesions may grow together, and large areas of the leaf may die.
First symptoms are brown spots at the tips of young leaves.
Each young spot has a dark brown netted design within the lighter brown area of the spot. These lines are best seen when the leaf is held up to the light. First symptoms are brown spots at the tips of young leaves. Each young spot has a dark brown netted design within the lighter brown area of the spot. These lines are best seen when the leaf is held up to the light.