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Brown patch lawn disease
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May is a month eagerly awaited by many turf lovers.

As temperatures rise, lawns begin to green up.

Fertilizer has been spread and weed killer has been applied. Lawnmower blades have been properly sharpened.

The first few weekends of cutting grass have gone well, and your turf seems fit for a major league ball park.

However, after a few days you start to notice that large circular patches of dead grass have started invading your precious lawn. You just may have brown patch, a common turf fungal disease.

Brown patch is a disease caused by the fungus Rhizoctonia solani.

The fungus is actually called by different names depending on what type of grass it affects.

On cool season grasses, such as Tall Fescue, it is called brown patch.

On warm season grasses, like Bermuda and Zoysia, it is called large patch.

Both large patch and brown patch are the most commonly diagnosed turf diseases in Georgia.

Because the fungal disease can occur on many different species and cultivars of grasses, symptoms can vary.

It can show up as rings or blotchy areas of brownish turf anywhere from 5 inches to 10 feet across.

Spots often appear as "smoke rings," with a thin brown ring with green grass on the inside and outside.

This happens when the fungus spreads out from a central area, and new leaf blades grow back from the surviving stems.

If you suspect you have brown patch, pick some blades of grass from the outer edge of the blighted area. You might be able to see tan lesions with darker brown borders.

Brown patch is most prevalent when daytime temperatures reach above 80ºF and nighttime temperature above 60ºF, as well as during periods of high humidity.

The disease is more severe in areas of turf that experience more than 10 hours of leaf wetness per day.

Grasses being mowed at heights shorter than recommended tend to show more signs of brown patch. Lawns that are over-fertilized with too much nitrogen are more susceptible to the disease.

There are several management methods that can be used to lessen the incidence of brown patch in your lawn.

Don't use too much nitrogen fertilizer.

Use only an amount needed to maintain reasonably healthy green turf.
Nitrogen encourages new shoot growth, and the tender new shoots are the most favorable part of the plant for the fungus to attack. Try using fertilizers that are lower in nitrogen and have moderate levels of phosphorous and potash.

If you see signs of brown patch, discontinue nitrogen use until the disease has cleared up. It is best to test your soil to find fertilization rates tailored to your soil and avoid over-fertilizing.

Increasing your mowing height in many cases will promote a healthier grass, and healthy grass is the best defense against disease. If possible, increase air circulation around your lawn by removing thick vegetation from bordering areas.

Minimize shading of the turfgrass by pruning out over-reaching tree branches.

Water your grass early in the morning.

This will allow the leaf blades to dry off during the heat of the day.

Wet leaves during the night are the perfect environment for fungal development.

Also, try watering deeper and less frequently. This will reduce leaf wetness and will promote deeper root systems in the turf.

If you have a severe case of brown patch, fungicides may be required.

However, many of these are expensive and only available to licensed pesticide applicators.

For fungicide options, contact the extension office at (706) 265-2442.