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Key for Identification of Landscape Turfgrass Diseases1
M. L. Elliott and G. W. Simone2Key for Identification of Landscape Turfgrass Diseases
The following is a general key that may help in making a preliminary diagnosis. Please see the following section for more specific diagnoistic characteristics, and information concerning the time of year the disease is most likely to occur.
A. Distinct patches of yellow to brown-colored turfgrass are present.
1. Patch areas are less than 3 inches in diameter. Leaf spot lesions present.
2. Patch areas are greater than 3 inches in diameter. Leaf spot lesions not present.a. Ring or arc of lush growth or dead grass; mushrooms may be present.
b. No rings or arc of lush growth.
i. Affected areas are distinct circular patches. Leaf pulls out of leaf sheath very easily.
Brown Patch
ii. Affected areas are irregular patches of 8 to 24 inches diameter or larger with mixture of yellow and dead grass. Roots are short and black. Stolons may be rotted also.
Take-all Root RotB. No distinct patches are present.
1. Orange 'spots' present on leaves; 'spots' rub off easily.
Rust
2. Orange 'spots' not present on leaves.
a. Leaf spots present.
i. Primarily on bermudagrass and ryegrass. Leaf spots have wide range of sizes.
'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 late spring and summer. Narrow, dark brown 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.
Slime Mold
ii. Grass is chlorotic (yellow) or has mottled leaves associated with general decline.
Pythium Root Rot and/or NematodesDiagnostic Features and Control of Turfgrass Diseases
The following section will describe the common diseases found on turfgrasses used in the landscape in Florida, primarily St. Augustinegrass. It is set-up in the following format.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 (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.
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 section of this chapter or other chapters in the Florida Lawn Handbook for more details on specific cultural practices such as nutrition or water management.
Chemical Controls: Chemical control treatments (fungicides) are listed as the common name only. Refer to Table 1 of the Turfgrass Disease Management section of the Florida Lawn Handbook 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. Afterall, to replace diseased leaf tissue the grass plant must produce new leaves.
Footnotes
1. This document is SS-PLP-1, a series of the Plant Pathology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. This information is included in the Florida Lawn Handbook, SP-45. For a copy of this handbook, request information on its purchase at your county extension office. First published: July 1991. Revised: April 2001.2. M. L. Elliott, Associate Professor, Plant Pathology, Fort Lauderdale Research and Education Center; and G. W. Simone, Emeritus Professor, Plant Pathology Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.
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 extension publications, contact your county Cooperative Extension service.
U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Larry Arrington, Dean.
Copyright Information
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