Leaf Spot and Melting-Out is Active

Leaf Spot of Kentucky bluegrass.

Leaf Spot of Kentucky bluegrass.

The leaf spot phase of this disease, caused by the fungus Drechslera poae, is apparent on susceptible Kentucky bluegrass turf at this time.

Melting-Out of Kentucky bluegrass.  A resistant cultivar (left) compared to a susceptible cultivar (right).

Melting-Out of Kentucky bluegrass. A resistant cultivar (left) compared to a susceptible cultivar (right).

To prevent severe damage from the melting-out stage of this disease during the next six weeks, avoid heavy applications of nitrogen in the spring (not more than 0.5 lb N / 1,000 sq. ft. / application of quick-release, water soluble formulations such as urea or ammonium nitrate), maintain the cutting height at or above 2 to 2-1/2 inches, remove excess thatch, and apply Armada, Compass, Disarm, Headway, Heritage, Insignia, mancozeb, Medallion, Tartan, or Velista now, per manufacturer’s recommendations.  Avoid the use of certain acropetal penetrant fungicides (e.g., benzimidazoles) this spring in areas with a history of leaf spot and melting-out, since these fungicides may intensify symptom expression.

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