Dollar Spot, Sclerotinia homeocarpa (possibly in complex with additional fungi)
Dollar spot on creeping bentgrass. Photo by Florida Division of Plant Industry Archive, Florida Department of Agriculture and Consumer Services, Bugwood.org.
IPM Steps to Reduce Dollar Spot
1. Sample for Pest
Confirm the presence of dollar spot before you treat.
Where to find it while inspecting: Most commonly on close mowed turfgrass (most varieties) but occurs on higher cut turf as well. On golf greens it is definitely a small round spot. In higher turf can be irregular circles 3–6" in diameter. Can be found from late spring through late fall, most often after a run of moist, cool weather. This fungus lives in soil and thatch and becomes active when there is prolonged leaf wetness during temperatures between 60 and 85 degrees. Mycelium (tiny white threadlike structures) may be visible early in the morning on wet grass but disappear later in the day. Look for tiny yellow spots on individual grass blades. The spot expands to a straw-colored band with reddish margins. The tan “band” becomes narrower than the rest of the leaf blade, even while the tips may remain green. Eventually the whole blade becomes brown.
2. Proper ID
Is it dollar spot?
Size and Appearance: 1–6" diameter circles, sometimes irregular.
3. Learn the Pest Biology
Dollar spot symptoms. Photo by Kevin Mathias, Bugwood.org.
What is the life cycle of dollar spot?
Life Cycle: The fungus is in soil and thatch and becomes active when temperatures are between 60 and 85 degrees, with prolonged leaf wetness.
Preferred Food Sources: Fungal diseases obtain nutrients through the breakdown of organic matter.
Preferred Habitat: Turf with prolonged leaf wetness.
4. Determine Threshold
How much dollar spot is too much?
Threshold: Threshold for dollar spot depends greatly on the aesthetic needs of a particular turf site, and is rarely a major problem on most athletic fields.
5. Choose Tactics
Creating a healthy soil condition and understanding turfgrass’s needs is the first step in reducing turf pests. What can I do to treat, reduce, or prevent Rust Diseases of Turf?
Best Management Practices: Use adequate nitrogen fertilizer reduces the severity of dollar spot (note that over fertilizing, especially at specific times of the year may increase the likelihood of other turf pests). Find ways to reduce or shorten periods of leaf wetness. Do not water in the late afternoon or evening. Prune back plant material such as tree branches or shrubs that shade sun or block air movement. Irrigate turf deeply during times of drought. Turf does best with heavy waterings for short periods of time rather than light waterings frequently.
Treatment Methods: In extreme cases, fungicide applications made early in the outbreak are generally effective.
Was the tactic successful? Record the date pests were first noted, and the tactic you used, and its success. Use one of our RECORD KEEPING tools.
For More Information:
When a pesticide application is necessary, all necessary and required precautions are taken to minimize risk to people and the environment and to minimize risk of pesticide resistance or pest resurgence. Pesticide use in your school may be prohibited or regulated by local policies or state and federal regulations. Risk reduction methods can include, but are not limited to, spot-treatment, the use of gel or paste bait formulations placed in inaccessible locations, injection into a crack or crevice, and other methods that reduce potential exposure.