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.
Rain is necessary for effective deposition of uredinospore involved in regional spore transport. Aeciospores from Berberis vulgaris are currently rare, but historically it was an important source of inoculum in northern North America and Europe. Mycelium or uredinia on volunteer wheat, are the most important source of inoculum in tropical and subtropical climates. Windblown urediniospores are usually from earlier maturing wheat from the south in the northern hemisphere, or from the north in the southern hemisphere. Urediniospores and aeciospore germinate when in contact with free water.