Brown Patch Not Only Fall Lawn Problem Says LSU AgCenter Horticulturist

Thomas J. Koske  |  4/19/2005 10:28:39 PM

News You Can Use For October 2004

Anyone who has a lawn has probably seen areas of Brown Patch disease browning out small to large areas in mid to late fall. LSU AgCenter horticulturist Dr. Tom Koske says Brown Patch is a common disease caused by the fungus Rhizoctonia solani.

To stop its spread, use a fungicide labeled for control of Brown Patch, Large Patch or Zoysia Patch.

Other diseases also can brown out areas of grass. Some are biotic (organism) diseases that may be an infectious fungus like that of Take-all Root Rot. Others are biotic noninfectious diseases that develop from organisms like algae, moss, slime mold or insects.

A third major category of disease-like problems is caused by abiotic (non-living) agents, such as chemicals, fertilizer, host, wear or freeze.

"We need to identify the causal agent first, before we can come up with the right cure," Koske says, adding, "It helps to review just what your lawn has been through in the last few weeks."

A sample of the problem area can be brought to a local county agent to be sent to the LSU AgCenter Plant Disease Clinic. Always take samples from areas that are just starting to go down – not from thoroughly dead spots.

Some noninfectious lawn problems may confuse people and cause them to apply a general fungicide instead of the correct treatment. Koske lists the problems and cures.

• Chinchbugs—browned out areas caused by the pests’ feeding in summer and early fall. Apply appropriate insecticide.

• Slime mold—a dark-gray or black powdery foliage cover that pops out overnight. It’s not damaging so ignore, and mow off or brush from the turf foliage.

• Algae—a green or black slimy surface in areas that hold water; cracks and peels up when dry. Improve drainage and turf thickness and apply copper sulfate.

• Dog spots—Distinct dead spots that develop quickly from urine burn. Irrigate to wash the salts out.

• Wear from walk path—traffic leads to wear and compaction of soil. Core or fork the area; lightly dust sand and sweep into the core holes; reroute traffic or relandscape as a path.

• Tan burned areas—uneven or overapplied fertilizer causes salt burn where concentrated. Irrigate to wash out salt burn where concentrated; irrigate to wash out salts.

• Dying turf in arcs and rings—usually found near tree canopy, drip lines; a type 1 (non-fruiting) fairy ring is choking the sod. Fork or spike to punch through the fungal mat and irrigate well; certain fungicides can help.

• Thin areas under a thick tree—too much shade for that turf species. Switch to St. Augustine; remove lower branches and thin the canopy for more light.

For more on this and related topics, look for Gardening and Get It Growing links in the Feature section of the LSU AgCenter Web site: www.lsuagcenter.com.  Additional yard and garden topics are available from an extension agent in your parish LSU AgCenter office.

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On the Internet: LSU AgCenter: http://www.lsuagcenter.com/
On the Internet: www.louisianalawnandgarden.org 
Source: Tom Koske (225) 578-2222, or tkoske@agcenter.lsu.edu

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