Diseases

Leaf Spot — Kentucky Bluegrass

Poa pratensis L.

A complex of fungal diseases of Kentucky bluegrass that causes lesions on leaf blades and thinning of the stand. The primary pathogen is Drechslera poae, which triggers the 'melting-out' phase affecting tillering nodes and roots.

In the reference 105 varieties crop Kentucky bluegrass, where this is mentioned in the description.

The primary causal agent of classic leaf spot in Kentucky bluegrass is the fungus Drechslera poae, which causes characteristic thinning of the stand known as melting-out. In addition to this, leaf spot is caused by Bipolaris sorokiniana, Nigrospora oryzae, Leptosphaerulina trifolii, fungi of the genus Pyrenophora, and Clarireedia spp., which is responsible for dollar spot.

Initial symptoms appear as purple, brown, or black spots that enlarge over time, become lighter in the center, and often develop a dark margin. As the Drechslera poae pathogen develops, the infection spreads from the leaves to the sheaths and roots, leading to mass shoot death during periods of temperature fluctuations.

Resistance to leaf spots in Kentucky bluegrass varieties is polygenic in nature. In breeding practice, specific resistance genes are not identified; instead, the level of infection is assessed using scoring scales within field trials, where varieties are compared by their level of genetic resistance.

General information about the subject — on the page Leaf spot diseases.

Sources8

Varieties of Kentucky bluegrass mentioned in the description

Selection based on the description text, not on official evaluation: these data are absent from registers. For specific variety details, please refer to its profile.