Kennelly, Megan, Commercial Management of Brown Patch of Cool?season Turfgrasses, Manhattan, Kansas, Kansas State University, September 2008

Kennelly, Megan M.

K-State Research Exchange

blighted turf from several inches to several feet in diameter (Figure 1). However, damage often develops in an irregular pattern without formation of discrete, circular patches (Figure 2). The pathogen primarily infects the foliage and makes tan lesions with a brown border (Figure 3). The leaves in affected areas are killed. On warm, dewy mornings you might find white, cobweb-like fungal growth in the foliage (Figure 4). Changes in the weather will slow the pathogen, new leaves will emerge, and the turf will recover in 2 to 4 weeks. In extreme cases, the pathogen can infect crowns Brown patch is a disease caused by the fungus Rhizoctonia solani. Tall fescue is particularly susceptible, but brown patch also occurs on perennial ryegrass and creeping bentgrass.Symptoms Tall Fescue: Initially, patches are dark purple-green then quickly fade to light tan or brown as the diseased leaves dry out. Diseased turf may appear drought stressed even when the soil is moist. The pattern of damage is variable. Damaged areas sometimes form circular patches of Commercial Management of Brown Patch  of Cool‑season TurfgrassesKansas State University Agricultural Experiment Station and Cooperative Extension ServicePlant Pathology  EP-146Figure 1. Discrete patches of brown patch in tall fescue. (Photo by P. Sell)Figure 2. Diffuse symptoms in tall fescue. (Photo by N. Tisserat)Figure 3. Brown patch lesion on tall fescue: tan with dark border. (Photo by D. Settle)Figure 4. Cobweb-like fungal growth is sometimes visible on dewy mornings. (Photo by D. Settle)Megan KennellyPlant PathologistDepartment of Plant Pathologyor stems, leaving weak areas of turf that are susceptible to invasion by weeds.Lower‑cut turf: In greens-height turf, the patches are yellow or brown (Figure 5), and they can be several inches to several feet across. In fairway or greens-height turf, when the disease is active, a grey or purple “smoke ring” is some-times visible on the edge of the patch (Figure 6). Conditions for DevelopmentBrown patch symptoms develop in 24 to 48 hours during warm, humid weather. The fungus becomes highly active when conditions are moist and night temperatures are above 65 degrees Fahrenheit. That is, if a lawn is dewy in the morning, with overnight low temperatures of 65 to 75 degrees, then conditions are favorable for brown patch. In Kansas, this usually occurs in July and August.Cultural ManagementThe first step is to manage the turf so conditions are not favorable for disease. This disease is favored by long periods of leaf wetness. Do not irrigate in the evening — this leads to a long, wet period overnight that extends into the dew period in the morning. Water in the morning instead. Fertility is also a key factor. Do not overfertilize, and do not fertilize if you have active brown patch. Finally, if you are seeding or reseeding, do not use overly high rates. Overly thick, lush lawns are highly susceptible to brown patch. Aerification and improved drainage can help prevent brown patch. Using fans on putting greens can improve airflow. Research at K-State has demonstrated that returning grass clippings to the lawn has no effect on brown patch.FungicidesIn many cases, the turf recovers on its own after a couple of weeks, especially after a change in the weather. However, chemical controls are available — see Table 1. Repeat applications may be necessary. Fungicides work better as a prevention before disease appears or when disease first appears. If you have a site with a history of brown patch, and a high aesthetic requirement, you might consider a preventative application around July 1 and another one or two applications as described on the product labels. Once the disease appears, it is impossible to “cure” infected plants. All you can do is protect the remaining healthy tissue to prevent further spread. However, the fungus has a latent period; it infects plants for a few days before we see symptoms. Therefore, you might have even more diseased tissue than you realize, and it is difficult for fungicides to stop those latent infections. Finally, keep in mind that other conditions can lead to brown turf (insects, thick thatch, poor soil conditions, other diseases such as Pythium blight), so if you have any doubts contact your local K-State Research and Extension office for help with a diagnosis.Fungicides for Brown Patch Always check the label to make sure the site (ex: home lawn/residential lawn/golf course) is allowed. It is the responsibility of the user to read, understand, and follow the label. Figure 5. Brown patch in greens-height turf. (Photo by R. St. John.)Figure 6. Active brown patch in perennial ryegrass. The fungus is visible as smoky-gray mycelium at the edge of the patch. (Photo by M. Kennelly)Active ingredient Fungicide group a Example trade names EfficacyTypical interval (days)azoxystrobin Strobilurin/QoI Heritage Good to excellent 14-28 Bacillus licheniformis Biocontrol EcoGuard Good 3-14 Bacillus subtilis, strain QST 713Biocontrol Rhapsody Little data available7-10 chlorothalonil chloronitrile Daconil Ultrex, Manicure, Concorde SST, Chlorostar, Echo, Pegasus L Good to excellent 7-14 copper hydroxide + mancozeb Junction Little data available7-14 fenarimol DMI Rubigan Good 7-14 fludioxonil Phenylpyrolle Medallion Good to excellent 7 fluoxastrobin Strobilurin/QoI Disarm Good to excellent 14-28 flutolanil carboximide Prostar Good to excellent 14-21 hydrogen dioxide Oxidizing agent Zerotol Inconsistent 7 iprodione dicarboximide Chipco 26GT, Proturf Fungicide X, Raven, Lesco 18 Plus, Iprodione Pro Good to excellent 14-28 mancozeb EBDC Fore, Manzate 200, Protect T/O, Dithane, Pentathlon Good to excellent 7 myclobutanil DMI Eagle Good 10-21 polyoxin D polyoxin Endorse Good to excellent 7-14 propiconazole DMI Banner MAXX, Spectator Good 10-21 pyraclostrobin Strobilurin/QoI Insignia Good to excellent 14-28 thiophanate-methyl benzimidazole Cleary’s 3336, Fungo, Proturf Systemic Fungicide, Systec 1998, Cavalier, T-Storm Good 10-14 thiram dithiocarbamate Spotrete, Thiram Good 7-10 triadimefon DMI Bayleton, Proturf Fungicide VII Good 14-30 trifloxystrobin Strobilurin/QoI Compass Good to excellent 14-21 triticonazole DMI Trinity Good to excellent 14-28 vinclozolin dicarboximide Curalan, Touché Inconsistent 14-28 Combination Productstrifloxystrobin + triadimefon Tartan Good to excellent 14-28trifloxystrobin + triadimefon Armada Good to excellent 14-28azoxystrobin + propiconazole Headway Good to excellent 14-28a Fungicide group abbreviations: EBDC = ethylene bis-dithiocarbamate, DMI = demethylation inhibitor (sterol inhibitor)Tables modified with permission from “Chemical Control of Turfgrass Diseases 2008” by P. Vincelli and A.J. Powell, University of KentuckyKansas State University Agricultural Experiment Station and Cooperative Extension ServiceEP-146 September 2008K-State Research and Extension is an equal opportunity provider and employer. Issued in furtherance of Cooperative Extension Work, Acts of May 8 and June 30, 1914, as amended. Kansas State University, County Extension Councils, Extension Districts, and United States Department of Agriculture Cooperating, Fred A. Cholick, Director.Brand names appearing in this publication are for product identification purposes only. No endorsement is intended, nor is criticism implied of similar products not mentioned. Persons using such products assume responsibility for their use in accordance with current label directions of the manufacturer.Publications from Kansas State University are available on the World Wide Web at: www.oznet.ksu.eduContents of this publication may be freely reproduced for educational purposes. All other rights reserved. In each case, credit Megan Kennelly, Commercial Management of Brown Patch of Cool-season Turfgrasses, Kansas State University, September 2008.

Commercial management of brown patch of cool-season turfgrasses

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Commercial management of brown patch of cool-season turfgrasses

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