The Top 6 Most Common Lawn & Turfgrass Diseases

he fungus known as Rhizoctonia Solani is responsible for the Brown Patch lawn disease.

Whenever the summer heat is unleashed on our lawns, we have several good reasons to be worried! These intense temperatures weaken our grasses to the point where they become vulnerable to a wide variety of debilitating diseases. The same usually applies for cold temperatures, as well. Most of these diseases involve fungi, and trust me when I say that they aren’t fun guys! Bacteria and other microorganisms are also capable culprits to keep in mind. Every homeowner should be wary of the most common diseases and how to stop them from spreading all over their property. The old adage of “prevention is the best medicine” applies to dealing with lawn and turfgrass diseases just as well. Now, let’s dive into the list of the usual suspects that lawn service experts deal with on a regular basis.

Brown Patch (Rhizoctonia Solani)

These ugly patches are perhaps the most common of the common diseases seen in the lawn service industry. Several parts of the country will see this disease, and it most often affects cool season turfgrasses. When humid summer nights with temperatures around 65 to 70 degrees (F) come into play, this disease strikes at its hardest. While it is pretty easy to spot once it has spread, it’s quite hard to catch it early. It literally looks like brown patches of dead grass, but not all dead grasses are the result of this fungal disease.

Large Patch (Rhizoctonia Solani)

This disease is an interesting case, because it is caused by the same fungus that causes Brown Patch, but it has a few distinct differences to be aware of. For starters, it mainly targets warm season turfgrasses such as zoysiagrass and bermudagrass. Also, it typically occurs in spring or autumn rather than summer. The prime weather conditions for it are overcast, moist, and cool. As the name would imply, this offender has a large area of effect. It starts out at around the size of a baseball, but it can develop into an area the size of a car! When the disease is clearly in motion, the turf around the edges of the patch will look discolored, and sometimes small bits of healthy turf can be seen at the center of the patch.

Red Thread (Laetisaria Fuciformis)

This fungal bad boy mainly affects bermudagrass, bluegrass, fescue, bentgrass, and perennial ryegrass. It thrives most of all in cool, humid conditions, and it shows up most often in lawns grown in soils with poor nutrient density. If you see thin, red hairs or strands on the ends of your grass blades, then you definitely have it. This disease can survive for years if left unchecked, so if you don’t like your lawn having red highlights in its “hair,” then you’d better be vigilant!

Pythium Blight (Pythium Aphanidermatum)

When half of your name is Blight, you know you’re dealing with a menace! Our dangerous friend here is a foliar disease, which means that it relates to leaves. Fungi have a role to play in this disease, as well. It is classified as a water mold, and outbreaks are most commonly associated with poorly drained soils or damp, humid conditions in turfgrass canopies where the leaves don’t dry enough. Knowing this, the prime time for the disease to strike is when newly seeded areas receive daily irrigation. Symptoms of the blight include circular areas 1-3 inches in diameter and foliage with a gray, soaked appearance. 

Pink Snow Mold (Microdochium Nivale)

You might be thinking: “A disease with a pink coloration should be easy to spot, right?” Well, this offender is notable for only staying pink for a short period of time. In areas where cool, humid weather is king, this mold can occur year round. Initial symptoms tend to include small, circular patches that may have a soaked appearance around the edges. The patches can become tan and look bleached under dry conditions. Like a chameleon, it can elude you with a clever change of color.

Summer Patch (Magnaporthe Poae) or Necrotic Ring Spot (Ophiosphaerella Korrae)

These two diseases are caused by different fungi, but they are incredibly identical and hard to distinguish from each other, so they share a spot. They both primarily target Kentucky bluegrass, and the symptoms almost always end up being circular patches (as usual) of brownish or tan turf. Their differences lie in how they start. Summer Patch obviously begins in the summer, and the initial symptoms are small areas of wilted grass blades. Necrotic Ring Spot usually begins in the spring, and the initial symptoms are small, light green spots on your lawn.

What Should You Do To Counter?

None of the diseases I listed above are a walk in the park, and that’s why you need to take the initiative to make your lawn tough to take down. There are multiple measures to take regarding keeping your lawn safe during the summer. It’s no secret that a lot of these measures involve watering habits and lawn mowing practices. Staying clean and dry is the key to avoiding lawn diseases, much like with human diseases. You should only water in efficient patterns when you need to. As for your lawn mowing, you need to make sure that you’re cutting precisely with the right mower and supplemental gear. Of course, there are times when it’s too late to apply preventative measures, so that’s when you call for fungicide. These chemical tools are not a soft touch, and a lawn care professional should definitely take the lead on applying it. There are a wide variety of fungicide products to deal with the wide variety of fungal diseases out there, so always ask for a thorough inspection before purchasing any of them.

It’s not easy thinking about lawn and turfgrass diseases, because we’ve got enough human diseases to worry about on a day-to-day basis! It seriously pays to know the early signs and symptoms, though. A beautiful lawn can easily be transformed into something akin to a post-apocalyptic wasteland, and the homeowners themselves could be in danger if the fungi get way out of hand. If your lawn is dealing with the difficulties of any of these diseases, then don’t hesitate to call your trusted local lawn company to handle things swiftly and safely.


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