DOLLAR SPOT
Caused by: Sclerotinia homoeocarpa F. T. Bennett
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.
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 20ºC. 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 20ºC 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