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Anthracnose1
M. L. Elliott and G. W. Simone2Anthracnose
- Pathogen: Colletotrichum graminicola
- Turfgrasses Affected: Primarily centipedegrass, but it is known to occur on all warm-season turfgrasses.
- Occurrence: This disease is normally observed in the spring during periods of high moisture (rain or heavy fog) and warm temperatures. Disease severity is often greater on stressed turfgrass, especially during springs following cold winters.
- Symptoms/Signs: Leaf infection appears as reddish-brown to brown spots that are often surrounded by a narrow yellow halo. Single spots may span the blade width causing leaf yellowing and then death of the leaf. Tiller infection results in girdling of stems and the development of small, yellow patches of turfgrass ( Plate 4 ).
CREDITS: G. W. Simone
Plate 4. Anthracnose symptoms on centipedegrass.
- The fungus can be observed with a hand lens. It will appear as small, black, cushion-like structures (acervuli) with black spines (setae) extending from the cushion. These structures will be found at the base of leaves next to the stem.
- Cultural Controls: Avoid potassium deficiency. Do not apply excessive nitrogen during potential disease development periods. Do not use readily available forms of nitrogen such as soluble liquids or quick-release nitrogen sources just prior to or during these periods. Instead, use slow-release nitrogen sources. Apply a balanced fertilizer containing equivalent amounts of potassium, preferably a slow-release potassium form.
- Avoid drought stress. Irrigate deeply to saturate the root zone. Irrigate only in the early morning hours (between 2 and 8 AM) when dew is already present. If the diseased areas are associated with compacted soils, alleviate the compaction. If thatch is excessive, renovate.
- Chemical Controls: azoxystrobin, chlorothalonil, myclobutanil, propiconazole, thiophanate methyl, triadimefon, and trifloxystrobin.
- Chlorothalonil cannot be applied to a residential lawn, but it can be applied to turfgrass in a business or industrial landscape.
- Refer to "Turfgrass Disease Managment " section of the Florida Lawn Handbook for explanations of cultural and chemical controls.
Footnotes
1. This document is SS-PLP-56, 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: 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.
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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.
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