Brown patch is a common

turfgrass A lawn is an area of soil-covered land planted with grasses and other durable plants such as clover which are maintained at a short height with a lawnmower (or sometimes grazing animals) and used for aesthetic and recreational purposes. L ...

fungal disease that is caused by species in the genus ''

Rhizoctonia ''Rhizoctonia'' is a genus of fungi in the order Cantharellales. Species form thin, effused, corticioid basidiocarps (fruit bodies), but are most frequently found in their sterile, anamorphic state. ''Rhizoctonia'' species are saprotrophic, but ...

'', usually ''

Rhizoctonia solani ''Rhizoctonia solani'' is a species of fungus in the order Cantharellales. Basidiocarps (fruit bodies) are thin, effused, and web-like, but the fungus is more typically encountered in its anamorphic state, as hyphae and sclerotia. The name ''Rhi ...

''. Brown patch can be found in all of the cool season turfgrasses found in the United States. Brown patch is most devastating to:

Bentgrass ''Agrostis'' (bent or bentgrass) is a large and very nearly cosmopolitan genus of plants in the grass family, found in nearly all the countries in the world. It has been bred as a GMO creeping bent grass. Species * '' Agrostis aequivalvi'' ...

(Agrostis sp.),

ryegrass ''Lolium'' is a genus of tufted grasses in the bluegrass subfamily (Pooideae). It is often called ryegrass, but this term is sometimes used to refer to grasses in other genera. They are characterized by bunch-like growth habits. ''Lolium'' is ...

(Lolium sp.), Annual bluegrass (Poa annua), and

Tall fescue ''Festuca arundinacea'' ( syn., ''Schedonorus arundinaceus'' and ''Lolium arundinaceum'') is a species of grass commonly known as tall fescue. It is a cool-season perennial C3 species of bunchgrass native to Europe. It is an important forage gr ...

(Festuca arundinacea). Brown patch is also found in

Kentucky bluegrass ''Poa pratensis'', commonly known as Kentucky bluegrass (or blue grass), smooth meadow-grass, or common meadow-grass, is a perennial species of grass native to practically all of Europe, North Asia and the mountains of Algeria and Morocco. Altho ...

(Poa pratensis) and Fine fescue (Festuca sp.) but this is rare or does minimal damage. Brown patch is known as a foliar disease, so it does not have any effect on the crown or roots of the turf plant.

Symptoms

Brown patch symptoms differ depending on the various maintenance practices performed on the turfgrass (mowing height, fertilizer, watering, etc.) Symptoms on turfgrasses that are wet for extended periods and are closely mowed will produce a distinctive gray-purplish bordered ring "smoke-ring" that is up to 50 cm in diameter. While on taller cut grasses that are not wet for extended periods of time will begin to produce patches that can be several feet in diameter and may have a "frogeye" appearance. White mycelium can be found on dew-covered turf in the early part of the morning. Penn State
/ref> On a closer look at the grass leaf blades (usually on Tall Fescue) you maybe able to see tan to brown small, irregular shaped lesions.

Disease cycle

The Rhizoctonia species thrives in temperatures ranging from 70 °F to 90 °F but can survive in freezing temperatures. Brown patch is most common when night temperatures fail to drop below 68 °F and during extended periods of high humidity or prolonged leaf wetness. The Rhizoctonia species has two specific fungi that affects the turf plant at different times of the year. In most cases Rhizoctonia solani will cause Brown patch in June throughout early July. While when temperatures begin to heat up and the air becomes more humid Rhizoctonia solani will be replaced by Rhizoctonia zeae. It has been found that the Rhizoctonia species is capable of surviving in the soil for many years without affecting turfgrass. During the winter months the fungus will lie dormant in the grass tissue or soil and form into resting bodies called sclerotia.

Cultural control

Similar to most turfgrass diseases one of the best cultural practice to prevent Brown patch is by incorporating new disease resistant turfgrass varieties. To find these new cultivars you can visit turfgrass seed distributors, extension specialists, or visit the National Turfgrass Evaluation Program website at: ww.ntep.org If incorporating disease resistant varieties of turfgrass is not an option then focus on better management practices. Some of the management practice include reducing thatch, having adequate drainage, and removing

dew Dew is water in the form of droplets that appears on thin, exposed objects in the morning or evening due to condensation. As the exposed surface cools by radiating its heat, atmospheric moisture condenses at a rate greater than that at wh ...

during hot and humid weather. Dew can be removed from the grass from mowing, using a backpack blower, or dragging a hose across the grass. Install an internal drainage system if you have severe drainage problems. Improve air circulation and avoid irrigation practices that will leave moisture on the grass blades for extended periods of time. An adequate aeration program will relieve compaction and improve drainage.

Aeration Aeration (also called aerification or aeriation) is the Systems engineering process, process by which air is circulated through, mixed with or solvation, dissolved in a liquid or other substances that act as a fluid (such as soil). Aeration proces ...

should annually disrupt between 15 and 20% of the total surface area. Be sure that you are not applying excess nitrogen to your soil. Most balanced fertility programs for Kentucky Bluegrass lawns will consist of applying two to five lbs of nitrogen/1000 sq.ft. a year.

Chemical control

If severe enough or on high valued turf (ex. golf greens) summer patch can be controlled with the use of fungicides. The application of

fungicides Fungicides are biocidal chemical compounds or biological organisms used to kill parasitic fungi or their spores. A fungistatic inhibits their growth. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality, ...

is usually done on a curative basis. Apply fungicides at the very first sign of Brown patch symptoms. In traditionally bad areas that cause severe damage to the turf a preventative fungicide application will work best. Fungicides should be applied according to the instructions on the label, the application of fungicides containing thiophanate-methyl and/or chlorothalonil in weather above 90 °F have been proven ineffective against Rhizoctonia zeae. Minimize the cost of applying fungicides by selecting fungicides that will work on a wide range of turfgrass diseases at the same time. Effective fungicides includes: *Benzimidazoles : Pro Turf *Carboximides : Prostar *DMIs : Banner, Bayleton *Dicarboximides : Proturf Fungicide X, Touche *Dithiocarbamates : Captan *Nitriles : Daconil *QoIs : Heritage, Compass, Insignia *Antibiotics : Endorse (polyoxin D) *Phenylpyrroles : Medallion

References

{{reflist Turfgrass diseases