Rusts

All cool season turfgrass species.

• Early symptoms of Rust diseases appear as light-yellow flecks on leaves or stems.
• The flecks enlarge, elongate, and turn yellow in colour.
• The yellowed area of the infected spots enlarge and elongate parallel to the leaf or stem axis as the infection matures.
• The leaf blade turns yellow starting at the tip and progressing to the base.
• The infected areas rise above the epidermis and then rupture, releasing spores that are yellowish-orange to reddish-brown in colour.
• Severe disease infection causes the shoot to turn yellowish to reddish-brown and slows growth.
• As individual plants die, the turf thins.

• Rust diseases typically occur in early spring through mid-summer.
• Rusts favour moist, low-light areas.
• Leaf wetness is required for fungal growth.
• Depending on the species, Rusts favour temperatures between 18°C and 30°C.
• Severe rust infections occur on slow-growing turfgrass particularly those with low nitrogen levels and/or water stress.

• Convert to a turfgrass seed blend that is resistant to rust diseases found in the area.
• Apply adequate levels of nitrogen and other nutrients
• Remove clippings from turf.
• Reduce shade and improve air circulation.
• Regulate irrigation to minimise the amount of time moisture remains on the leaf surface.
• Water deeply and infrequently.

Grasses growing under stressful environmental conditions are most easily parasitised by the Rust fungi.