Lawn & Turf Tips:  Leaf Rust

Leaf Rust (Puccinia graminis)               

Disease Description

Lawn or leaf rust appears as an orange-yellowish powder on your  grass blades. Overall, your turf may take on a yellow, red or brown appearance. You may also notice that when you are walking on your lawn that you shoes have an orange residue on them.  The rust is easily tracked into your homes either by your shoes or your pets when you are out in your lawn.

Predisposing factors

• This occurrence is primarily during the late summer-early fall when weather conditions are drier.
• It typically develops on lawns that are growing slowly due to low nitrogen and low water availability. With the turf grass growing more slowly, the fungus has plenty of time (approximately 7 - 14 days) to produce the spores in the infected grass blades.
• Seasons with excess rain may have rust outbreaks due to a depletion of available nitrogen.
• Cool nights with heavy dew and light, frequent rainfall add to the ideal conditions for rust to develop.
• Warm, cloudy, humid weather followed by hot, sunny weather also contributes to the promotes lawn rust.
• The grasses most susceptible to rust are Kentucky bluegrass, perennial ryegrass, and tall fescue.
• The fungus spreads by air, water, shoes, equipment, and vegetative turf material (sod).
• In cases where the rust continues into the late fall, the infected plants may become more susceptible to winter injury.
• Young grass and seedlings tend to be more affected by rust then more established lawns.
  

Cultural Control

The best way to control the rust:

• This is best accomplished by a good fertilizing maintenance program and proper irrigation habits which promotes grass growth.
• Water infrequently but deeply. You should irrigate in the morning preferably before 10:00 am. Avoid watering in the evening because it will increase the duration that the moisture is on the leaves which increases the chance of disease.
• Mow frequently and bag or collect the clippings when possible.
• Also, when possible, wash of the blades of your mower to prevent spread of rust to other grass blades.