Large Patch Grass FungusNovember Pest of the Month.

Large Patch Grass Fungus

What is Large Patch Grass Fungus & What Causes It?

Large Patch Grass Fungus previously known as Brown Patch is a cool weather disease that affects warm season grasses. The disease is caused by Rhizoctonia solania fungus. Rhizoctonia solani fungus is very similar to the one that causes brown patch disease of cool-season turf grasses in mid-summer.

Large Patch Fungus can occur on almost any type of turf species, most common: Zoysiagrass, St. Augustine grass and centipede. Bermudagrass can also be affected by Large Patch Grass Fungus however it causes less damage. It can arise on residential and business lawns as well as golf courses. Like the name applies, Large Patch Disease is a result of blighted turf in large areas or patches in areas that are 1' to 2' in diameter to over 20 feet in diameter. Large Patch Disease occurs in the fall and spring as small discolored patches that expand over time (see photos above & below). Normally patches appear in early to mid-October as temperatures drop and get cooler.

Jump to section: Appearance | Symptoms | Habitat | Treatment | Tips

General Appearance

Large Patch Grass Fungus is dormant during the winter much like turf. Areas that have been affected by this disease may become prone to injuries from the cold. If Large Patch Grass Fungus disease isn't controlled it will appear in the same locations every spring and fall and will get worse if the conditions are right (see disease favoring conditions). Large Patch Grass Fungus grows outward in all directions creating a circle. Often times this disease if often noticed in late October and early November then in the spring.

Large Patch Grass FungusYou may be able to tell if you have Large Patch Grass Fungus if you check the base of the brown (off-colored) grass blade along the border. If the grass blade is comes loose easily, is tan to brown in color and looks rotted, more than likely you have a Large Patch Grass Fungus disease (left photograph). To know for sure if your lawn has this disease, give one of our Lawn Care Pest Specialists a call today.

  • Large Patch Grass Fungus can also be spread by lawn mowers, foot traffic and grass clippings.
  • Mow areas affected by Large Patch last and wash the grass clippings off of the mower each time you mow.
  • When this fungus is active do not apply nitrogen fertilizer.
  • Water only when necessary when LPGF is present and only when dew is already present to try and prevent it from spreading even more.

If you think you have a lawn problem such as Large Patch Grass Fungus problem give us a call today at (386) 362-3887 and let one of our lawn care specialists handle it.

Also listen to recorded radio interviews with Roy Crain Jr. discussing this month's pest.


Large Patch Grass FungusThe centers of patches appear to look dead, thin and sunken. This area may become susceptible to weed growth. Large Patch Fungus varies in size and shape however they tend to be circular. If this fungus isn't controlled, it can return every spring and fall in the same places! When the disease is active an orange border will appear around the affected area. This orange area is new infected blades of grass.

  • It is most active along the border of the affected area where it is expanding to healthy grass.
  • Rings or patches of blighted turf grass from 1' to 2' up to 20 feet in diameter.
  • Leaf spots, blighted rings and patches and "smoke rings".
  • thin, brown borders around the diseased patches that appear most frequently in the early morning.
  • Blackened or rotted sheaths and stolons of turf grass near the soil layer.
  • The fungus may worsen in areas of excess shade, cooler temperatures, areas that stay moist for extended periods of time and can be even worse where water drainage is poor.

If you think you have a lawn problem such as Large Patch Grass Fungus problem give us a call today at (386) 362-3887 and let one of our lawn care specialists handle it.

Habitat (Favoring Conditions)

Large Patch Grass FungusLarge Patch Grass Fungus is prevalent in fall and spring months and is favored by cool temperatures and wet conditions. In order for Large Patch to grow it needs to have water on the grass blades so this disease is often noticed in areas that are shady such as under trees, fence lines and shrubs. Large Patch is most severe when temperatures at night are in the upper 50's and lower 60's with a mid-day temperature in the 70's; normally spring and fall. Once summer temperatures get into the upper 80's and 90's the disease activity stops until fall.

  • Active at cool temperatures on warm-season grasses in the spring and fall (77° to 83°F canopy temperatures).
  • Occurs in areas that experience extended periods of wetness or low areas subjected to standing water.
  • In shady and moist areas Large Patch Grass Fungus may not be circular.
  • More aggressive when turf is over-fertilized or over-watered.
  • Wet conditions can include: heavy dew, abundant/frequent rain, over-irrigating.


The best way to treat a Large Patch Grass Fungus problem is by giving our highly trained Lawn Pest Specialists a call. They will come out, assess the problem and will set the appropriate course of action. Call today at (386) 362-3887 for more information and to schedule an appointment.

Listen to recorded radio interviews with Roy Crain Jr. discussing this month's pest.

Cultural Disease Management Tips

  • Minimize the amount of shade.
  • Improve soil drainage.
  • Mow grass at regular intervals.
  • Use an adequate level of nitrogen, particularly in the spring and early summer.
  • Irrigate turf as infrequently as possible to avoid spreading the disease. When irrigation is necessary, water during the morning hours when dew is still on grass blades.
  • Reduce thatch by vertical cutting.
  • Core aerify; not during Fall or Spring when the disease is most active.
  • Increase the height of cut.
  • Lightly fertilize turf in early spring to encourage new growth.
  • Apply contact and/or penetrant fungicides on a preventive basis.

If you think you have a lawn problem such as Large Patch Grass Fungus problem give us a call today at (386) 362-3887 and let one of our lawn care specialists handle it.

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