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Science-based gardening information for Colorado communities from CSU Extension, Denver Botanic Gardens, and Green Industries of Colorado.

1522 – Dollar Spot of Turfgrass   arrow

Dollar spot, a fungi that infects turfgrass, gets its name from the silver-dollar-sized spots it forms on closely mowed bent grass, like the grass found on a golf course green. On lawns, however, the fungi may infect larger areas in just a few days. Patches may coalesce to encompass several square feet. In Colorado, dollar spot affects Kentucky bluegrass, annual bluegrass, Bermuda grass, fine-leaf fescues, perennial ryegrass and zoysia grass.

How is dollar spot diagnosed?

Dollar spot of turfgrass

To determine the presence of dollar spot, inspect an individual blade of grass from a healthy looking part of the lawn. Then select a blade from an area just outside of a dead-looking patch of grass. Inspect the individual grass blades for a white lesion or spot that is pinched in the middle and looks like an hourglass. The lesion often occurs in the mid-section of the leaf blade and may have a purple margin. This bleached, hourglass-shaped lesion is characteristic of dollar spot.

When is dollar spot most prominent?

Dollar spot is especially active during hot, humid weather and when leaf blades are wet for prolonged periods of time. A stressed lawn is more susceptible to the disease than a properly maintained lawn. When dollar spot infects a lawn that’s stressed due to soil compaction, heavy thatch, improper fertilization or insect damage, a fungicide won’t solve the problem.

How can I prevent dollar spot?

Dollar spot of turfgrass

Proper lawn care is the key to managing dollar spot. A compacted or heavily thatched lawn may require core aeration. Proper irrigation also is important. Water between 9 PM and 8 AM, so watering corresponds with -but doesn’t extend -the natural dew period. It’s important to minimize leaf wetness as much as possible. If you mistake dollar spot for an under-watered lawn, when in fact the lawn is over-watered, the disease may get much worse.

When planting new turfgrass, choose varieties that are resistant to dollar spot, if they’re available in your area. But don’t choose a particular variety only for that reason. It’s best to seed or sod with a mix of two or more turf varieties that have desirable characteristics.

Do fungicides prevent dollar spot?

Dollar-spot fungi have developed varying degrees of tolerance to fungicides, so use them only as a last resort. As with any chemical, be sure to read and follow label instructions.

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