Rust symptoms initially appear as small yellow or white slightly raised spots on upper and/or lower surfaces of leaves. These spots enlarge and form reddish-brown or rust-colored pustules that are about 1/8 inch in diameter and contain thousands of microscopic summer spores (urediniospores). Spores (fungus seeds) are readily released from the pustule and give a rusty appearance to anything they contact. Rust can be distinguished from other leaf spots in that these spores rub off onto your fingers, while blights and bronzing do not.
- Affects
- Level of Concern
- Gardeners take note
- What months
- Jul–Oct
- Treatment / Useful Links
Helpful ways to help prevent rust are: crop rotation, planting at the correct time (May 25-June 15), water so that foliage will dry before dark, adequate plant spacing. Helpful link: http://www.ext.colostate.edu/pubs/crops/02936.html