The first evidence of a rust infection are pin-point yellow flecks on the upper side of leaves. The yellow flecks will deteriorate and turn to orange pustules. Reddish-brown rust pustules usually develop first on the upper side of lower leaves or stems.
Epidemics are most detrimental before or during flowering.
There is a reduction in plant vigor, seed filling, and root growth in infected plants. Also, rust infections may predispose the plant to other diseases such as powdery mildew. Causative Agent Leaf rust fungus can overwinter in Kentucky on fall seeded wheat but most often it is blown into Kentucky from southern states. Warm temperatures and high humidity or rain favor rust development. After soft dough, rust will have little effect on crop yields.