Anthracnose
Causal Agent
Colletotrichum spp.
What is Anthracnose?
Anthracnose is a group of diseases that cause dark, sunken lesions on leaves, stems, flowers, and fruits. Anthracnose infects many deciduous and evergreen trees and shrubs and in some regions also infects fruits, vegetables, and turf grass
What are the Symptoms of Anthracnose?
Turf that succumbs to Anthracnose will see the pathogen infect the stem, crown, upper root tissue and lower foliar tissue, causing dark brown to black discolouration.
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Leaves of infected plants turn yellow to a light tan to brown before dying. Younger leaves often turn red.
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In anthracnose foliar blight, red to brown elongated lesions can appear on leaf blades, enlarging to blight the entire leaf. Blighted leaves turn yellow and begin to die back from the tip
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Basal stem and leaf sheath rot, affected plants are easy to pull out.
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Infected areas are seen as irregular-shaped patches, and affected patches are reddish brown colour before yellow then tan to brown.
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A black stain may occur at the base of infected plants, this is an acervulus, a black fungal fruiting body. It can be seen using a hand lens often growing on the dead or infected tissue.
Anthracnose INFO SHEETWhat causes Anthracnose?
The fungal pathogen most commonly responsible for causing anthracnose diseases in turf is Colletotrichum graminicola. The pathogen can be identified by the presence of distinctive acervuli (fruiting bodies) which appear on infected plant tissue as black hairlike protrusions. These fungi are known to colonise plant tissue on most turf species, infecting crown and root tissue (known as basal rot), or foliage (foliar blight).
When does Anthracnose occur?
In general, the conditions favouring Anthracnose are:
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Warm and humid conditions - particularly temperatures over 25°C.
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More than 10 hours a day of leaf wetness for consecutive days.
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Hot summers in cool temperature areas are when the disease is most noticeable.
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Soil compaction and low amounts of nitrogen also contribute to disease occurrence.
What turfgrasses are especially susceptible to Anthracnose diseases?
Wintergrass (Poa annua), Bentgrass, Kentucky Bluegrass, Fescue & Couch. Though bentgrass suffers from anthracnose foliar blight, it is not known to become infected with the basal rot which commonly affects P. annua.
What can I do to manage Anthracnose diseases?
Anthracnose will often infect plants in a weakened or stressed state. Management practices that help reduce plant stress can be beneficial:
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Maintaining adequate nutrition and a balanced fertility level (avoid phosphorus and potassium deficiencies)
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Proper irrigation (avoid overwatering and underwatering), and regular aeration.
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Infected turf can often require micromanagement to reduce symptoms, including raising mowing height and reducing mowing frequency
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Decrease surface traffic.
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Core aerate and overseed in autumn but do not core aerate while disease symptoms are present.
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Convert to less susceptible varieties of turfgrass on fairways.
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Avoid management practices that encourage humidity and extended leaf wetness.
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Make preventative fungicide applications where the disease is a chronic problem.
