A lot of microbes love to call lawn grasses 'home.' It's hard to fight back when you don't know which microbe to blame. No wonder Google searches for "lawn disease pictures" are so numerous.
As you'll find below, several universities and organizations supply great pictures online. Pictures may not be enough, unfortunately. Many diseases and insects leave look-alike damage, at least to the untrained eye.
The month of occurrence, recent weather conditions, location, soil, and especially turf type all determine the possibilities.
Determine the Turf Type
Above all, it is crucial to know what grass species make up the lawn. It's almost always a mix of species, all selected for the local climate and soil. Here are several ideas to help determine what type of grass you have:
- Check the back of the leftover grass seed bag or visit the garden center or website where you purchased the seed to read the contents of the seed mix. Seed companies almost always list the varieties in the mix.
- If you "inherited" the lawn and have no idea what species are growing, here are several guides that give an idea of what is likely to have been planted:
- The US National Arboretum offers an overview of the best grasses for each area. The lawn was probably planted from a mix recommended for the area. (See our article on free, local lawn and turf advice from the Cooperative Extension programs in all 50 states.)
- Scotts Company offers turfgrass variety recommendations based on zip code. This helps narrow the species likely to be in your lawn.
Lawn Disease Identification
Three resources may help with identification:
The Departments of Crop Science and Plant Pathology at North Carolina State University created a website for turf disease identification using simple checkboxes.
First, choose (or guess, based on the resources above) the grass varieties in the affected lawn and check the month when symptoms appear.
These two choices lead to additional tabs, where you can check off symptoms.
As you refine the selection criteria, the disease list narrows. Each disease has an easy-to-read information card and clear photographs that help distinguish the symptoms.
If you don’t know the grass varieties in the lawn, you can still click through the disease list and look for symptoms and photos.
Also, visit Michigan State University's Turf Disease identifier. This site asks whether the turf is located at a home or golf course, offers checkboxes for 13 symptoms, then asks for irrigation status, time of year, and host plants.
Both of the NC State and Michigan State sites help demystify a lot of hard-to-identify turf problems.
Not Just for Turf Pros
Also visit TurfDiseases.org, which is targeted to turf professionals who manage golf courses and athletic fields. The rest of us can benefit from the detailed pictures this site offers. There are diagnostics for cool season and warm season turf afflictions as well as technical information on how to fight back. This site also supplies regional turf disease information.