 |
ANTHRACNOSE
ON TURFGRASS
| Colletotrichum
graminicola |
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Introduction
Anthracnose of turfgrass is found in many areas and climates. It attacks
most turfgrasses but is most damaging on Annual Bluegrass (Poa
annua) and Bentgrass (Agrostis palustris) in
North America. The fungus is an active pathogen of young leaves but
it is most readily detected on senescent plant parts.
Symptoms
The pattern of symptoms depends largely on weather conditions.
Rotting of the basal stem is the most prevalent symptom detected during
cool, wet weather. Water-soaked stem lesions become dark in color
and the leaf blades eventually yellow and die (Fig. 1). The central stem
can be pulled from the plant quite easily revealing a blackened base.
Microscopic examination reveals the dark mycelium and hyphopodia.
Reddish-brown lesions may occur when warm weather, dry
soil and increased humidity within the turf canopy occur. Reddish-brown
irregular patterns on the turf may form as the disease develops. Over
time, the patterns turn yellow, tan then brown. Mycelium and acervuli
may be detected on the lower stems or on seasoned tissue. Characteristic
setae, that look like black, bristly hairs (Fig.
2), are often associated with the acervuli.
Figure 1: Symptoms of Anthracnose
on turfgrass. (provided by Dr.
Eric B. Nelson, Cornell University) |
Figure 2: Microscopic view of setae of the fungus.
(provided by Dr. Eric B. Nelson,
Cornell University) |
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Disease Cycle
The fungus, Colletotrichum graminicola, overwinters on
living plant material. Stressed turfgrass is most susceptible to infection.
The fungus penetrates the root, crown, and/or leaf tissue during high
humidity and wet weather conditions.
Management Strategies
Keeping the turf healthy and reducing stress, such as soil compaction,
may help in reducing the damage observed on the plant material. Proper
watering and correcting fertilizer deficiencies, especially phosphorus
and potassium, will be particularly helpful in reducing damage caused
by Colletotrichum graminicola.
Many products are available for use against Anthracnose. For home
lawn use in New York State, use Heritage or Golden Eagle to treat Anthracnose. Some fungicides containing the active
ingredients chitosan, propiconazole, triadimefon, or thiophanate-methyl may also be registered to treat Anthracnose. Before purchasing,
be sure the product is labelled for the intended use, and follow directions
on the label. Commercial applications please refer to the appropriate
commercial pest management guidelines, or contact your local Cooperative
Extension Office for more information on currently registered products.
Created, KLS, 8/99; Updated, SLJ, 1/07
This publication contains pesticide recommendations.
Changes in pesticide regulations occur constantly, some
materials mentioned may no longer be available, and some
uses may no longer be legal. All pesticides distributed,
sold, and/or applied in New York State must be registered
with the New York State Department of Environmental
Conservation (DEC). Questions concerning the legality and/or
registration status for pesticide use in New York State
should be directed to the appropriate Cornell Cooperative
Extension Specialist or your regional DEC office. READ
THE LABEL BEFORE APPLYING ANY PESTICIDE.
__________________________________________________________________________________
The Plant Disease Diagnostic Clinic
at Cornell University is located at 334 Plant Science Building,
Ithaca, NY, 14853. Phone: 607-255-7850, Fax: 607-255-4471,
Email: kls13@cornell.edu
or slj2@cornell.edu |