Occurs worldwide wherever wheat is grown. Damage is greatest when the disease becomes severe before the grain is completely formed. In areas favorable for disease development, susceptible cultivars cannot be grown. Grain is shriveled due to the damage to the conducting tissue, resulting in less nutrient being transported to the grain.
Severe disease can cause straw breakage, resulting in a loss of spikes with combine harvesting.
Uredinia generally appear as oval lesions on leaf sheaths, true stem, and spike. Uredinia can appear on the leaves if other diseases have not killed them. Uredinia are brick red in color and can be seen to rupture the host epidermis, on the leaves uredinia generally penetrate to sporulate on both surfaces. Infected areas are rough to the touch. Wind can effectively disperse urediniospores over great distances.