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Brown Patch and Other Lawn Diseases

Sadly, even the healthiest lawn is not entirely immune to blight such as brown patch and other lawn diseases.  Let’s look at the cause and treatment for some of the most common of them.

Brown patch becomes evident almost immediately as circular areas of dead and brown grass surrounded by a narrow dark ring.  The blades sometimes appear to be a purplish color before they turn brown.  What’s worse, once it has started it  spreads quickly.  Brown patch is caused by a fungus called Rhizoctonia solani.  The name of this fungus comes from ancient Greek rhiza (“root”) plus ktonos (murder”).  That sort of says it all, doesn’t it.  This fungus prefers warm, wet weather so most outbreaks occur in the early summer months with the most active growth occurring later in the summer, when temperatures reach 800 – 850 and humidity is high.  The usual treatment for brown patch is the application of a fungicide as soon as you notice symptoms and continuing this treatment as recommended on the product label (usually every 2 – 4 weeks).  One way of helping prevent the fungal infestation is proper watering of your lawn.  Excessive moisture contributes handsomely to creating an environment in which Rhizoctonia solani thrives so a correctly designed and regulated sprinkler system can work wonders in keeping your lawn free of this fungus.

Dollar spot disease has the appearance implied by its name.  These small, silver dollar sized and somewhat sunken circles of tan grass may not look very formidable, but they can destroy your lawn if they expand.  Dollar spot disease is caused by the Sclerotinia homoeocarpa fungus.  Some newer species of creeping bentgrass have been bred specifically for dollar spot disease resistance but, for those of us who don’t want to rip up and replace our Kentucky bluegrass or St. Augustine or bermudagrass lawns, there are fungicidal treatments available, some of which claim to be non-chemical.  Aeration of the lawn is important in controlling this disease, as is proper irrigation.  A correctly regulated sprinkler system is essential in mitigating the growth of this pestilent fungus.

The name “fairy rings” sounds whimsical, conjuring up images of a group of little fairies holding hands and dancing around in the evening mist.  What it really is, though, is an arc or ring of mushrooms that has sprung from fungi breaking down organic material in the soil or thatch.  Hmmm.  That’s not nearly as enchanting as fairies dancing about.  The fungi develops outward from the center of the ring.  As the innermost part of the ring dies, it releases nitrogen into the soil which will turn the grass above it a darker green.  The fungi also produces mycelium which is a kind of cotton-like webbing.  This webbing can harden and prevent water penetration into the soil, killing the grass above it.  Remediation includes improved aeration and proper watering.Fairy rings seem to be more prevalent in soils that are poorly fertilized or under-watered.

Red thread is another lawn ailment that is caused by a fungus.  Red thread appears as pink or red patches in smaller or larger diameters.  Up close, you’ll see reddish thread-like structures between the blades.  Lawns growing in soil that is low in nitrogen are most susceptible to red thread.  The fungus that creates red thread, Laetisaria fuciformis, lives in the soil and the thatch and fortunately does not attack the grass roots or crown, so it does not kill the grass.  Remediation of red thread is fairly simple and involves aeration, proper drainage, and the application of nitrogen to the affected area.

Crop circles are areas of lawn that have been burnt by alien spaceships landing.  This is rare, however, and seems to occur most often in New Mexico.  Apparently, the UFOs can be warded off by wearing tinfoil hats.

Extraterrestrials aside, most common lawn blight can be prevented and controlled by sound fertilization and irrigation practices.

Call Smart Earth Sprinklers for all your sprinkler system programming, maintenance and repair needs.  Call us today at (512) 694-1147.

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