Peanut rust appears as minute leafspots or flecks that are visible from both sides of the leaf. As the number of infections increase and become older, leaves become a "rusty" yellow color. Infections may also develop on stems and leaf petioles.
Lesions viewed from the under surface of leaves will exhibit masses of reddish-brown spores that are easily spread by air movements to other leaves. These spores are capable of causing new infections and increasing the severity of disease.
Peanut rust commonly develops in a radiating pattern from a single spot within a field. These spots can rapidly increase in size during periods of wet, warm weather. Peanut rust apparently does not overwinter in the United States, but blows into the production area with subtropical storms or hurricanes. This accounts for the erratic occurrence of this disease in Virginia and North Carolina.