Yellow Patch

Disease

Cool season brown patch

Rhizoctonia cerealis

Photos

Yellow patch, also known as cool season brown-patch, is a Rhizoctonia pathogen similar to that of brown patch. Symptoms first appear as smaller (6-12 inches in diameter) patches, with yellow margins. Damage occurs on creeping bentgrass and annual bluegrass putting greens, and is typically a cosmetically damaging disease which does not cause severe turf damage. Individual patches may coalesce to form large irregularly shaped yellow areas.

Yellow patch is most prevalent in the early to mid-spring, and can also occur in mid-fall. Outbreaks occur on cool season turfgrasses during extended periods of cool, cloudy, wet weather. The fungus is most active between 50° F and 75° F.

Crops Affected: turf

Damage

The location of this disease is golf courses. General symptoms are a circle, patch, and irregular coloring. Foliar symptoms are browning, and yellowing. This can occur during the months of March, April, May, June, September, and October. Hosts of the disease are Kentucky Bluegrass, Tall Fescue, Fine Fescue, Creeping Bentgrass, and Annual Bluegrass.

Management

Yellow patch will typically subside when temperatures warm up and conditions become dryer. Control with fungicides is not usually recommended, as symptoms disappear after a few days of warm dry weather.
If fungicides are needed to control a severe case of yellow patch, effective fungicides include the strobilurin products, DMI fungicides, and polyoxin D.