Rust on turfgrass has been common this season. Yellow flecks that later turn into orange pustules can appear on bluegrass, fescue, bentgrass, zoyzagrass, and Bermudagrass. Each pustule contains about 50,000 spores of the fungus. When walking through grass with a severe rust infection, white shoes can become orange.
It's typical for the disease to show up in late summer to early fall. Rust is favored by overcast weather, high humidity, heavy dew formation, and temperatures in the low 70's. Rust can also develop after rain showers followed by sunny, warm weather. Symptoms are usually more severe where nitrogen levels are low and plants are drought stressed.
Most often the disease is managed with a balanced fertility program. Mow regularly to remove infected leaf tips before spores are produced. Irrigate when necessary to relieve drought stress, but avoid evening watering. Most grass cultivars have adequate resistance to rust diseases. Blending turfgrass varieties, when seeding, is a good strategy to help avoid severe outbreaks.
Fungicides are available for rust control, but usually aren't necessary.
This article originally appeared in the September 13, 2002 issue, p. 119.