Lawn Fungus

Rusty Razor Sharp Blades of Grass


It’s a gloomy, yet great day in the Wonderful World of Weed Man.  The sky is overcast and threatening to sprinkle rain down upon us!  Hopefully it holds out so we can get some work done!  Last week we began the main part of our lawn disease series by discussing Necrotic Ring Spot.  Continuing on this week, we will delve into the topic of Rust.

Rust?  Yes, you can get rust on your lawn.  But your lawn is not metal you say.  Well, it’s not really rust in the conventional sense.  Rust Fungus is a disease that occurs on many types of grasses when their growth is slowed.  The actual name of the fungus is Puccinia spp.  This typically happens late summer, or early fall.  In fact, I noticed some on my lawn as I was mowing it this weekend.

Rust is fairly easy to identify.  Rust will causerustbuckets.jpg light yellow spots or flecks on the grass blade.  The spots will enlarge over time and create little spores that appear as orange-yellowish powder.  It looks very similar to actual rust that you might see on oxidized metal.  Hence the name ‘Rust.’  Walking through grass with significant amounts of infection will disturb and release the spores within these pustules and leave a distinct orange color on one’s shoes. These spores, carried by the wind or equipment, spread the disease to other areas during the growing season.

As mentioned before, when the lawn starts to decrease its growth rate, rust can begin to develop on the lawn.  Drought, or low water availability will slow down growth.  Lack of nitrogen nutrients can do the same thing.  If a lawn is over-watered, it can deplete the available nitrogen quicker than if it were to be watered as recommended.  Rust is more likely to develop when temperatures are cooler, early morning dew is heavy, and the sky is overcast with clouds creating a low light high humidity environment.

Alternating weather patterns changing in cycles from cool wet weather to hot dry weather can also create suitable conditions for the disease. Rusts survive on living and dead leaf tissue and in the thatch layer of turf grass and/or on alternate hosts (such as barberry or other ornamental plants) when they are not affecting the grass blades. Only when weather conditions become suitable do they begin to cause a concern on the lawn.


Rust is considered a minor disease in turf grass, but I can become severe, or create opportunity for more damaging diseases to start on the lawn.  In most cases the spores will only attack the leaf blade causing wilting and thinning of the grass.  The rust will interfere with the grass blades ability to photosynthesize.  As the grass becomes weakened it is more susceptible to other diseases and/or pests.

So what do you do if you see rust in your lawn?  Here are some great practices to help get rid of the rust:

  • Provide a light application of fertilizer to help promote recovery.
  • Reduce thatch with core aeration
  • Reduce shade and improve air circulation
  • Avoid watering at night
  • Water deeply and infrequently to increase growth
  • Mow the lawn frequently to keep it at a moderate height. Also, be sure to rinse off lawn equipment to prevent the spread of disease.

Rust generally does not need a chemical control.  Although there are chemicals that can help control fungus in the lawn, we generally do not recommend it.  There is a time and place for use of chemical treatment, but too often homeowners just want a quick fix.  Many times chemical control for fungus treats the symptoms and not the underlying cause.  Chemical control can get very expensive as it needs applied consistently and often to work.  If you make the necessary changes to your cultural practices it will improve on its own.

If you are seeing rust in your lawn, and need some help with it, don’t hesitate to call the Weed Man! 208-888-9911 #wecareforyourlawn