Dollar spot is a common fungal disease evident in many home lawns at this time of year. All of the commonly used turfgrasses in Nebraska including bluegrass, tall fescue, fine fescue, perennial rye and zoysia grass are susceptible to Dollar spot although some cultivars of each grass species have greater resistance to the disease.
Dollar spot gets its common name from the size of the affected spots of grass in the lawn. Usually the spots will initially be about the size of a silver dollar. Large leaf spots or lesions develop across the entire width of the leaf blade and are light tan or whitish with a medium reddish-brown border. Dollar spot lesions are also typically pinched in at the middle of the lesions giving an hourglass effect. Infected leaf blades eventually die leading to quarter- or silver dollar-sized dead spots in the lawn.
On coarser bladed grasses like tall fescue, the lesions may develop along the edges of the leaf blade and could be confused with Brown patch. Brown patch, however, has a much darker brown or purplish-black margin around the leaf spot.
When dew is present, white, cobweb-like fungal growth appears on infected leaf blades, but disappears as the dew dries.
Dollar spot is most severe on lawns that do not receive adequate fertilization. Warm, damp nights that result in high humidity around the grass canopy for long periods of time are optimal for the growth of Dollar spot fungal spores. Injury is usually most severe when daytime temperatures are 70-80 F degrees and the soil in dry. Excessive thatch and low soil nitrogen and potassium levels also promote Dollar spot development.
Dollar spot can be controlled using the following techniques.
- Provide the turf with adequate fertilizer.
- Promote good air circulation by pruning landscape plantings and trees.
- Keep mowing and other activities to a minimum when the grass is wet.
- Apply a preventive fungicide if Dollar spot has been a problem in the past. The fungicides such as benomyl, Banner, Bayleton and chlorothalonil are all labeled for Dollar spot control.
Sarah Browning is an Extension Educator with the University of Nebraska- Lincoln Extension in Dodge and Saunders Counties. She can be contacted by phone at 727-2775: by mail at 1206 W. 23rd Street, Fremont, NE 68025: or by e-mail at sbrowning2@unl.edu
