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Publication #SS-PLP-1

Key for Identification of Landscape Turfgrass Diseases1

P. F. Harmon and M. L. Elliott 2

The following is a general key that may help in making a preliminary diagnosis of landscape turfgrass. Additional diseases not listed are commonly diagnosed from golf course turfgrass. Please see the linked documents for more specific diagnostic characteristics, and information concerning the time of year the disease is most likely to occur. In many cases, the key will help narrow down the potential disease problem you face. Read more information by clicking the links in the key below to see EDIS publications on these diseases. If you cannot narrow down the potential problem using the key, consider consulting your local county extension office, or submit a sample to an Extension Plant Diagnostic Clinic.

Diagnostic Features and Control of Turfgrass Diseases

Each linked EDIS publication in the key above will have the following sections. The types of information given in each section is explained below.

Disease: This is the correct name for the problem.

Pathogen: This is the Latin name of the fungus that causes the disease. The first word is the genus name, and the second word is the species name.

Turfgrasses Affected: This is a list of the turfgrasses that are normally affected by this disease. If one or two turfgrass species are more likely to be affected than others, that is indicated.

Occurrence: The exact time when a disease will occur is dependent on the environment. The time of year when the disease is most likely to occur is indicated. Since there are distinct climatic variations in Florida (north vs. south; coastal vs. inland), these variations should be considered when diagnosing a disease problem. The situations (ex: rain or fog) or stresses (ex: nitrogen deficiency) that will cause the disease to occur or make it worse are stated.

Symptoms/Signs: This section describes the appearance of the turf when diseased (symptoms) and what if any fungal structures, molds, or other evidence of the pathogen (signs) may be present.

Cultural Controls: This section describes the cultural controls that can be employed to prevent the disease or to help the turfgrass recover from the disease. Cultural controls require that everyone involved with management of the turfgrass work together to solve or prevent the disease problem. Refer to the cultural control sections of the specific EDIS publication for the disease being managed or consult other resources like the Florida Lawn Handbook for more details. Specific cultural practices such as nutrition or water management differ between some diseases, so an accurate diagnosis is important.

Chemical Controls: Chemical control treatments (fungicides) are listed as the common name only in many EDIS publications. Refer to the Pest Control Guide for Turfgrass Managers (http://turf.ufl.edu/pdf/2012_UF_Pest_Control_Guide.pdf) or the Homeowner’s Guide to Fungicides for Lawn and Landscape Disease Management (http://edis.ifas.ufl.edu/pp154). for an example of a corresponding trade name. Fungicide labels change frequently, so read the label to determine if the product is still legal to use on the turfgrass site.

Fungicides suppress or inhibit fungal growth. They do not stimulate turfgrass growth. In many cases, diseases occur when the turf is not growing rapidly, usually due to sub-optimal temperatures. Under these circumstances, recovery from a disease will be slow. After all, to replace diseased leaf tissue the grass plant must produce new leaves.

Tables

A. 

Distinct patches of yellow, light straw or brown-colored turfgrass are present.

1. Distinct patches are less than 3 inches in diameter.

 

a. Leaf spot lesions with light tan to straw colored centers present. Can occur on any grass.

Dollar Spot

 

b. On seahore paspalum only, chocolate to dark brown patches with brown colored centers present.

Microdochium patch

2. Patch areas are greater than 3 inches in diameter. Leaf spot lesions not present.

 

a. Affected areas are distinct circular patches as big as several feet across. Leaf pulls out of leaf sheath very easily. Patch may have distinct yellow to orange border.

Large Patch

 

b. Affected areas are irregular patches of 8 to 24 inches diameter or larger with mixture of deficient yellow and dead grass throughout patch. Roots are short and black. Stolons may be rotted also.

Take-all Root Rot

B. 

Rings or arcs of lush green to dead grass; mushrooms may be present.

1. Rings or arcs larger than 15 inches across, may repel water, may be mushrooms present.

Hydrophobic Fairy Ring

2. Rings less than 15 inches in diameter, narrow consistent width, do not repel water, on closely mown Bermudagrass.

Mini-ring symptoms of Rhizoctonia Leaf and Sheath Spot

C. 

No distinct patches are present.

1. Orange 'spots' or blisters present on leaves; orange color rubs off easily.

Rust

2. Orange 'spots' not present on leaves.

 

a. Leaf spots present.

 

 

i. Primarily on bermudagrass and zoysiagrass. Leaf spots have wide range of sizes.

Bipolaris Leaf Blotch aka 'Helminthosporium' Leaf Spot

 

 

ii. Primarily on St. Augustinegrass in summer. Leaf spots oval to irregular with brown borders and tan to gray centers.

Gray Leaf Spot

 

 

iii. Primarily on St. Augustinegrass in earlyspring and summer. Narrow, dark purple leaf spots initially, then become oblong, irregular spots with dark tan centers with brown borders.

Cercospora Leaf Spot

 

 

iv. Primarily on centipedegrass. Reddish-brown to brown spots surrounded by yellow halo.

Anthracnose

 

b. No leaf spots present.

 

 

i. Grass covered with an easily removed slimy or crusty growth usually gray, purple, or bright yellow in color.

Slime Mold

 

 

ii. Grass has scattered chlorotic (yellow) leaves associated with general decline.

Pythium Root Rot

 

 

and/or Nematodes

Footnotes

1.

This document is SS-PLP-1, a series of the Plant Pathology Department, UF/IFAS Extension. This information is included in the Florida Lawn Handbook, SP-45, avalable for purchase at http://ifasbooks.com. First published: July 1991. Revised February 2014.

2.

Philip F. Harmon, associate professor, Plant Pathology Department, UF/IFAS Extension, Gainesville, FL 32611, and M. L. Elliott, professor, Plant Pathology, Fort Lauderdale Research and Education Center.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.