You Are Here: Management Updates 2009 Archive April 8, 2009

Date: April 8, 2009
Category: Diseases
Subject: Basal Rot Anthracnose

The first turfgrass disease specimens received by the UMass Extension Plant Diagnostic Lab have exhibited basal rot anthracnose caused by Colletotrichum graminicola.

Basal rot anthracnose can be an extremely destructive disease in putting greens. This disease has become more commonplace in recent years and is considered one of the most important diseases of greens. The increased incidence is attributed to common practices such as mowing extremely low, maintaining low nitrogen fertility, and the frequency of abrasive cultural practices. Basal rot anthracnose occurs during cool periods in the spring and can remain active in annual bluegrass throughout mild winters. Areas of intense traffic, soil compaction, and shaded and wet spots are particularly vulnerable. Symptoms occur as orange or yellow spots about the size of a dime. Infected plants can coalesce into large, nonuniformly affected areas which appear yellow or reddish brown. Large areas may thin out or die completely. Removal of sheath tissues to expose the stem base reveals a black, water-soaked rot of crown tissues. Basal rot is difficult to suppress when it becomes a chronic problem on annual bluegrass greens. The disease seldom attacks both annual bluegrass and bentgrass on the same green; this supports the theory that there are different biotypes of the pathogen.

To manage basal rot anthracnose, divert traffic from affected areas and avoid such practices as rolling, double cutting, core aeration, vertical cutting, or brushing. Use walk behind greensmowers and raise the height of cut temporarily. Irrigation should be applied only as needed to prevent wilt. A modest (0.125-0.25 lb N/1000 sq ft) application of nitrogen should be combined with a fungicide application.  Curative sprays include azoxystrobin (Heritage™), fenarimol (Rubigan™), fludioxonil (Medallion WP™), myclobutanil (Eagle™), polyoxin (Endorse™), propiconazole (Banner™), triadimefon (Bayleton™), thiophanate-methyl (Fungo 50™), or trifloxystrobin (Compass™). Follow with a separate application of chlorothalonil at a high rate.

Where basal rot is a chronic problem on greens, fungicides should be applied preventively in combination with an improved nitrogen fertility program. Greens should be spoon fed with nitrogen (0.1-0.2 lb N/1000 sq ft) every two to three weeks. In autumn after symptoms have eased, core aerify and overseed.

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. 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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