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Brown Patch

a most destructive disease
 

Active In Hot Weather

Brown patch disease is one of the most destructive of all turf diseases. It sneaks up on you and destroys large areas of turf virtually overnight when the weather conditions are just right.

Brown patch isn't picky, it attacks a wide variety of grass types, and really likes the lawns receiving large amounts of fast release nitrogen fertilizer.
 

Brown Patch Loves The Hot Summer

Brown patch is really a summer disease that's caused by a fungi called Rhizoctonia. The disease begins to show growth when temperatures reach 65 degrees, but its most active growth occurs at temperatures of 80-85 degrees when humidity levels are very high.

The fungi themselves survive the winter in plant debris (thatch) and enter the leaf tissue through wounds caused by mowing and through the pores (or stomata) when daytime temperatures get into the 70s. Infected turf can go quite a while without showing damage because its actively growing. But let the daytime temperatures reach the mid 80s and night time air temperatures stay above 70 degrees, and the grass will be under stress. Then damage can become visible almost immediately.

Once started, brown patch spreads fast. Brown patch damage first appears as circular areas of brown and dead grass surrounded by a narrow, dark ring. This dark, smoke ring is not always visible, but is more likely to appear in the early morning when there's dew on the grass. The disease grows out from a central point, so these circular areas can enlarge rapidly. Brown patch circles range from a few inches in diameter to several feet, and are not always true circles. Sometimes the patches grow together creating large irregular dead areas. Diseased turf first appears water soaked with leaf edges showing a wavy or wilted pattern, but soon dies completely and mats down creating a sunken affect.



Cultural Management: Helping To Prevent Brown Patch

Mow less frequently during periods of hot and humid weather. This reduces stress and the movement of the disease by being carried on your feet or mower. If possible, increase light and air penetration or movement by pruning overhanging trees and shrubs. During cooler seasons, open up the thatch layer with power aeration. If these cultural cures fail, a preventative fungicide program may have to be applied to control this most damaging of lawn diseases.



Summary:

Brown patch is the most damaging of all turf diseases.

Brown patch becomes most active when day temperatures are over 85 degrees and night air stays above 70 degrees.

Because infected plants may appear healthy, brown patch damage can occur very fast when condition are right.

Avoid high levels of nitrogen in fast release form it encourages brown patch development.