Southern corn rust

The uredial pustules of P. polysora are densely scattered over the surfaces of leaf blades, leaf sheaths and stalks on maize. The uredia are light cinnamon-brown, circular to oval, 0.2-2.0 mm long and generally epiphyllous. The few hypophyllus pustules were usually on or near the midrib. Uredia when ruptured and sporulating abundantly produce the rust symptom. The rust was most severe on the lower leaves; severity decreased with successive leaf position. Severely infected leaves became dry and defoliated prematurely, and in this case stalk lodging may occur. Some resistant hosts were characterized by abortive and isolated pustules surrounded by sharply defined, necrotic or chlorotic areas. Susceptible hosts had consistently greater incidence of pustules, which were larger, more tumid and ruptured earlier, and sporulated more readily than those on resistant hosts.