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Home International SportsNotes Weather conditions are becoming more favorable for anthracnose (Colletotrichum cerealis formerly called Colletotrichum graminicola). Incidence of the disease has been confirmed in parts of the Midwest. Most cases involve Poa annua (annual bluegrass) areas on greens and collars with the more annual biotypes being most susceptible compared to the perennial types. In most years samples at some time are received that have the disease on bentgrass.

Why is this disease being seen at this time? Beside the favorable weather many golf courses are preparing or have increased conditioning (2X mowing, extensive rolling, top dressing, growth regulation, etc) for special club events that contribute to the development of anthracnose by leaving turf stressed and in a weaken state. Remember this is a disease that is present in the turfgrass sward and just waiting for an opportunity to invade weakened plants. Weather conditions and ongoing infections from spring may also be involved.

Current weather conditions of high temperatures, high humid, and frequent thunder storms/ or over watering are IDEAL for the rapid outbreak and explosion of this nasty disease!

It is recommended that a careful inspection be done as soon as possible. Look for the classic signs and symptoms of the disease which include the irregular decline of patches of turfgrass or general thinning; the color can vary from tan / brown to rust / orange. The black spines (setae) of the acervuli can be seen with a hand lens, see the photo, for a good quick field identification. Get help or another opinion if there are any questions. If the disease is present and favorable weather patterns are forecasted to continue implementing an aggressive turfgrass health management strategy and a sound fungicide program. Remember this disease is seldom "controlled" with fungicides alone!

Cultural practices of greens to manage for healthy turf and reduce anthracnose:

Mowing:

* Avoid scalping and mowing stress any way possible.
* Do not mow when greens are wet (soft and/or spongy).
* Use solid rollers.
* Use walk-behind mowers and reduce mowing frequency (floating head mowers preferred).
*Raise mowing height. Research has shown that a 0.015 inch increase in mowing height can result in an improvement of turf health and reduced anthracnose (i.e.: from 0.125 to 0.141 inch).
* In some cases by rolling greens the frequency of mowing can be reduced and the height increased.

Fertility programs:

*Maintain greens with a sound fertility program for healthy turfgrass. (~ 3 lb N / 1000 ft² / year).
* Apply 0.1 to 0.125-lb. N/M sq. ft. from ammonium sulfate or urea every 7-14 days. Tank-mix with fungicide applications.
* Soil test and tissue test to insure an adequate fertility program of all essential elements are used.

Water management - drainage and irrigation:

* Install drainage systems or rebuild greens to correct poor drainage or design problems.
* Avoid excessive irrigation. Syringe to prevent wilt. Avoid extremes in soil moisture.
* Improve and/or provide proper drainage to maximize turfgrass health and vigor. *Address compaction problems.
* Avoid over watering and excessive wet soils and conditions of continuously wet thatch.

Minimize wounding, mechanical damage, factors that limit turf growth and stress from other pests:

* Avoid aggressive grooming operations (topdressing, dethatching, verticutting, brushing, aeration) when anthracnose is active. Light to moderate topdressing is often beneficial to improve health.
* When grooming operations cannot be avoided, apply fungicides tank-mixed with soluble fertilizers prior to grooming, even if anthracnose is not active. Syringe after grooming.
*Use PGRs as an effective tool to maximize turfgrass health and part of an Integrated Turfgrass Health Management Program. Do not stop or severely slow grow if recovery is needed.
* Monitor parasitic nematode activity in the spring and early summer as nematode activity may be another predisposition factor to the development of anthracnose during the summer and fall.

FUNGICIDES LABELED FOR ANTHRACNOSE ON TURFGASS

Normally do not use a fungicide from the same chemical class in succession, rotate whenever possible. As temperatures increase keep in mind the growth regulating side effects of sterol-inhibiting fungicides. Read and follow all label recommendations.

Preventative programs and strategies are recommended if there is a history of the disease. If the disease has advanced to basal rot anthracnose and severe; select the high label rate, shortest timing interval, apply in the proper amount of water to place the fungicide where the disease is active and to protect the host. It is usually recommended to rotate penetrant fungicides from the different classes shown: i.e. Thiophanate (CL 3336 or Fungo 50) in the first 7-10 days; followed by a strobilurin (Compass, Heritage, Disarm or Insignia in the second 7-10 days; followed by a sterol-inhibitor (Banner, Bayleton, Eagle, Trinity, Tourney, Chipco Triton or Rubigan in the third 7-10 days period. Consider including Chipco Signature in this rotation at least once per month. Endorse is an additional penetrant to consider however works best as a preventative fungicide. Contact fungicides are most effective if applied to completely cover the leaf tissue with minimal run-off.

NOTES: Spray volume recommendations: - systemics (most are upward moving only) 4 to 5 gal/ 1000 sq ft, - contacts and local penetrants 1 to 2 gal/ 1000 sq ft.

Strobilurin and thiophanate-methyl resistant biotypes of anthracnose have been reported. Select products that are known to work and monitor for fungicide resistance. If possible leave untreated areas as check plots to observe results.

For a list of fungicides available on turf and their mode of action see Families of Fungicides for Turfgrass (January, 2008)

Posted by Joseph Rimelspach & Michael Boehm