You Are Here: Management Updates 2007 Archive August 13, 2007

Date: August 13, 2007
Category: Diseases
Subject: Anthracnose

The arrival of typical summer weather with hot, humid days and warm nights resulted in the detection of anthracnose in many specimens submitted to the UMass Extension Plant Diagnostic Lab . In most cases, the anthracnose was limited to the foliage; in severe cases, the pathogen was also observed on plant crowns and several cases of basal rot were seen (even though this is primarily a cool weather disease).

Anthracnose is caused by Colletotrichum graminicola. The fungus survives as a saprophyte in plant debris or as a pathogen in infected tissue and attacks turf growing under low fertility, temperature stress, or both. C. graminicola usually infects grass blades from the tip down, especially freshly mowed grass and can be present on the leaves, roots, or stolons. The disease is most severe in areas of poor drainage, heavy traffic, and soil compaction. Basal rot can be extremely difficult to suppress when it becomes a chronic problem on annual bluegrass greens.

Anthracnose becomes more severe on stressed turfgrass; some of the stresses seen have been cultural and others the result of infection by root pathogens. Excessive amounts of thatch, unbalanced fertility, soil compaction, and recent top-dressing can contribute to this disease. Roots affected by ectotrophic root infecting fungi (Take-all or Summer Patch) or high populations of plant-parasitic nematodes can increase the occurrence and severity of anthracnose.

Increase mowing height, divert traffic from affected areas, and avoid potentially abrasive grooming practices such as double-cutting, aeration, and brushing. Anthracnose can be managed with light nitrogen applications and fungicide applications. Apply azoxystrobin (Heritage™), fenarimol (Rubigan™), propiconazole (Banner™), or Al-phosphonate (Signature™), water these materials in, and let dry. Follow with a separate application of chlorothalonil at a high rate. Greens should be spoon-fed weekly with nitrogen to encourage the growth and spread of healthy bentgrass.

Submitted by: M. Bess Dicklow

DISCLAIMER - As always, it is the responsibility of the applicator to verify the registration status of any pesticide BEFORE applying it. Different states have different regulations as well. Trade names of materials are provided for informational purposes only and do not substitute for a thorough and careful reading of the label and application according to label instructions. The author and the University of Massachusetts are not liable for any consequences of any pesticide recommendations. Mention of any trade name is not to be considered endorsement of a product.

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