The Lawn Man

Leaf Spot

Caused by: Bipolaris sorokiniana (Sacc.) Shoemaker, Curvularia spp., Dreschlera spp.

Leaf Spot

Plate 1: Dreschlera siccans on perennial ryegrass

Description

Symptoms depend on the grass species and the pathogen involved. Generally a yellowing or paling of the leaf blades may occur, accompanied with spots or lesions developing (Plate 1. Lesions may girdle the leaf and the portion above the girdle withers. The sward may thin or look drought stressed.

Where is leaf spot found?

Any area of turf, especially golf greens, tees, fairways, bowling greens, lawns, parks and sports pitches.

All grass species can be affected by leaf spots

When is leaf spot likely to attack turf?

During the summer months, when the temperatures are high. Humid conditions encourage outbreaks.

Effects of leaf spot

Minor infection may result in lesions on leaves but no other effects

Severe infection may thin the sward, cause dieback and leave patches with weak turf, affecting the aesthetic value and the playability of the turf

High risk situations

Leaf spots occur in mild and warm temperatures (around 20°C). As the temperature increases (25 - 35°C) blighting and melting out occurs.

High fertility

Moist conditions

Cutting heights lower than recommended for the grass species

Excessive thatch layers


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