The Lawn Man

Dollar Spot

Caused by: Sclerotinia homoeocarpa F. T. Bennett

Dollar Spot

Plate 1: Dollar spots on Poa annua

Description

Dollar spot lesions on leaves are a pale, bleached colour. They are bound at either end by a darker reddish-brown band separating the affected tissue from the healthy green tissue. Small (dollar size) spots of bleached turf occur on close mown grass (Plate 1). The spots may coalesce to form large areas of affected turf (Plate 2). White mycelium may be present on affected areas on dewy mornings, which disappear as the leaves dry.

Dollar Spot

Plate 2: Dollar spots coalescing

Where is dollar spot found?

Any area of turf, especially golf greens, tees, fairways and bowling greens.

In the UK, fescue dominant swards are at high risk of infection. Poa annua grass can also be severely affected.

When is dollar spot likely to attack turf?

During the summer months, when the daytime temperatures are above 20°C. Humid or thundery conditions can encourage an outbreak, as can heavy dews.

Low fertility swards are at more risk from dollar spot

Effects of dollar spot

The spots reduce the aesthetic appearance of fine turf, such as golf greens and create an uneven surface causing non-uniform ball roll.

On longer cut areas, such as tees, playability may not be affected (unless the outbreak is very severe) but the aesthetic appearance will be reduced

High risk situations

Heavy morning dew

Daytime temperatures 20°C and above

Low fertility situations

Excessively low cutting heights

Fescue dominant sward, although there is variation among subspecies and cultivars. Poa annua grass is also susceptible

Slowly growing turf

Moisture retentive turf surface


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