Dollar Spot Lawn Disease: Identification and Treatment

It starts innocuously — small, straw-colored spots scattered across your lawn, each about the size of a silver dollar. You might assume it’s dry spots, or perhaps some chemical burn. But within a week, those spots multiply and begin to merge, and what was a few isolated patches becomes a lawn riddled with dead, bleached areas that no amount of watering seems to fix.

That’s dollar spot lawn disease — one of the most economically significant turfgrass diseases in North America, affecting golf courses, athletic fields, and home lawns from coast to coast. The good news: once you understand what drives it, dollar spot is highly manageable with the right combination of cultural practices and, when necessary, fungicide treatment.

What Is Dollar Spot?

Dollar spot is a fungal disease caused by Clarireedia jacksonii (recently reclassified; you’ll still see the former name Sclerotinia homoeocarpa in older resources). It is one of the most researched turfgrass diseases in the world, primarily because of its impact on golf course turf — but it’s equally destructive in home lawns.

The fungus overwinters in infected plant tissue and thatch as dormant mycelium. When temperatures and moisture conditions become favorable, it activates and spreads from plant to plant through hyphal growth, water, foot traffic, and equipment movement.

Identifying Dollar Spot: Visual Symptoms

Accurate identification of dollar spot is important before you invest in treatment. The disease has several very distinctive characteristics that separate it from similar-looking problems like brown patch, drought stress, or fairy ring.

Patch-Level Symptoms

Spots are small — typically 2–6 inches in diameter at normal lawn mowing heights (1.5–3.5 inches). At lower mowing heights like golf fairways, spots may be as small as a quarter.
Bleached, straw-colored appearance — affected areas are tan to white rather than reddish-brown (which would suggest brown patch)
Irregular shapes at higher mowing heights, where spots coalesce into larger, amorphous areas
Scattered distribution across the lawn rather than one or two isolated patches

The Definitive Clue: Blade-Level Lesions

This is what separates dollar spot from almost every other lawn disease. Examine individual grass blades in and around affected areas:

Hourglass-shaped lesions — tan or straw-colored spots that span the full width of the blade, with reddish-brown margins on both sides
The lesion “pinches” the blade, creating the characteristic hourglass shape
In severe infections, multiple lesions may appear on a single blade, causing complete dieback from tip downward
The lesions are tan in the center with distinct dark reddish-brown borders — this color combination is highly diagnostic

Morning Mycelium

Under conditions of high humidity and morning dew, you may observe white, cobweb-like mycelium draped over affected areas and the surrounding healthy grass. This mycelium disappears as the dew dries and temperatures rise during the day. If you see this in combination with the small bleached patches, dollar spot is your almost certain diagnosis.

Dollar Spot vs. Similar Diseases

Feature	Dollar Spot	Brown Patch	Fairy Ring	Drought Stress
Spot size	2–6 inches	6 inches to several feet	Ring shape	Irregular, widespread
Blade lesions	Hourglass shape	Tan with brown border	None distinctive	Folded/wilted
Morning mycelium	White cobwebs	Dark smoke ring	None	None
Season	Spring through fall (50–80°F)	Hot summer (>70°F nights)	All season	Summer dry periods
Nitrogen relationship	Worsens with low N	Worsens with high N	Neutral	Neutral

What Causes Dollar Spot?

Understanding the conditions that trigger dollar spot is essential because the primary driver — low nitrogen fertility — is something you can directly control.

Temperature Range

Dollar spot is uniquely active across a wide temperature range: 50–80°F. This means it can be active in spring, early summer, and fall, unlike brown patch which requires hot nights above 70°F. This broad range is part of why dollar spot is so common — it can infect during multiple seasons.

Peak activity typically occurs when:

Daytime temperatures are in the 70–85°F range
Nighttime temperatures remain above 50°F
There are extended periods of leaf wetness (dew, rain, or irrigation)

The Nitrogen Connection

Low nitrogen fertility is the most important cultural factor driving dollar spot. This relationship is consistent and well-documented:

Turf that is nitrogen-deficient is dramatically more susceptible to dollar spot
A light application of nitrogen fertilizer is often the single most effective “treatment” for mild dollar spot outbreaks
Conversely, excessively high nitrogen (especially in hot weather) increases susceptibility to brown patch — so finding the right fertility balance matters

The reason nitrogen matters: actively growing, well-nourished grass produces leaf tissue rapidly and can outpace the rate at which the fungus damages blades. Slow-growing, nitrogen-deficient turf provides an ideal environment for dollar spot to persist.

Drought Stress

Drought-stressed turf is significantly more susceptible to dollar spot. When grass is moisture-stressed, its growth rate slows, it becomes more physiologically vulnerable, and recovery from fungal attacks is impaired. Interestingly, dollar spot thrives in conditions where the plant is drought-stressed but the leaf surface has adequate dew or moisture — a combination that’s very common in summer.

Leaf Wetness

Like most fungal diseases, dollar spot requires prolonged leaf wetness for infection to occur. Morning dew, frequent light rain, and evening irrigation all extend leaf wetness periods and promote disease spread. The fungus spreads most actively when:

Dew remains on leaves for 10+ hours
Fog or overcast conditions reduce drying
Irrigation is applied in the evening or at night

Low Mowing Height

Turf mowed at lower heights (below 2 inches) is more susceptible to dollar spot, primarily because:

Lower-cut turf is under greater stress
The canopy is more dense at the surface, reducing air circulation and drying
Individual plant roots are shallower and less resilient

Thatch Accumulation

A thatch layer thicker than 1/2 inch provides a protected reservoir for dollar spot mycelium and maintains higher humidity at the soil-canopy interface. Excessive thatch is a risk factor for many diseases, including dollar spot.

Grass Types Most Affected by Dollar Spot

Dollar spot can infect virtually all turfgrass species, but some are significantly more susceptible:

Highly Susceptible

Creeping bentgrass — the most susceptible; dollar spot is the #1 disease problem on bentgrass golf course putting greens
Bermudagrass — very susceptible, especially hybrid bermuda maintained at low heights
Zoysiagrass — susceptible, particularly in humid climates
Kentucky bluegrass — moderately to highly susceptible

Moderately Susceptible

Perennial ryegrass
Tall fescue
Annual bluegrass

More Resistant

Fine fescues (especially hard fescue and sheep fescue)
Buffalograss
Centipedegrass

Cultural Management: Reducing Dollar Spot Without Fungicides

For many homeowners, cultural controls alone can manage dollar spot effectively — especially if disease pressure is moderate. Focus on the following:

1. Maintain Adequate Nitrogen Fertility

This is the most impactful change you can make. If dollar spot is a recurring problem:

Test your soil to determine actual fertility needs — a soil test kit takes the guesswork out of fertilization
Apply light, frequent nitrogen applications during the growing season rather than infrequent heavy applications
For cool-season grasses, the primary fertilization windows are fall (September–November) and spring (March–May)
Choose slow-release nitrogen fertilizers to maintain steady nutrition between applications — this is more beneficial than a single large application
Don’t over-correct — excessive nitrogen in summer increases brown patch risk

2. Water Management

Water in the early morning (ideally 4–8 AM) so turf dries quickly
Avoid evening or nighttime irrigation — this is the single most common mistake that worsens dollar spot
When drought stress is present, water deeply and infrequently (1–1.5 inches per week) rather than frequent shallow irrigation
Use a catch can or rain gauge to measure actual water delivery — most homeowners significantly under- or over-water

3. Raise Mowing Height

If dollar spot is active, raise your mowing height by 0.5 inches. Taller grass is more stress-tolerant, produces more carbohydrates, and recovers from disease more quickly. For most cool-season lawns during summer:

Tall fescue: 3.5–4.5 inches
Kentucky bluegrass: 3–3.5 inches
Perennial ryegrass: 2.5–3.5 inches

4. Reduce Thatch

Core aerate annually in fall for cool-season grasses
Dethatch if thatch exceeds 1/2 inch — use a power rake or vertical mower
Topdress with compost after aeration to improve soil biology and thatch decomposition

5. Improve Air Circulation

Prune low-hanging branches and thin nearby shrubs to reduce humidity at the turf surface
Avoid dense plantings that restrict airflow near affected areas
In areas that stay damp chronically, consider improving drainage or transitioning to more suitable ground covers

6. Avoid Spreading the Disease

Don’t walk through actively infected areas when the turf is wet — foot traffic spreads mycelium
Clean mower blades and equipment when moving between infected and healthy areas
Remove grass clippings from heavily infected areas rather than redistributing them

Fungicide Treatment for Dollar Spot

When cultural practices aren’t sufficient — or when disease pressure is high on a high-value lawn — fungicide applications are highly effective against dollar spot.

Timing: Preventive Is Best

As with most lawn diseases, preventive fungicide applications are more effective than curative ones. Apply when:

Historical disease has been a problem (base timing on previous years)
Conditions are favorable (temperatures 60–80°F, extended dew periods)
You see the first scattered spots appearing — early curative treatment before widespread infection

Effective Active Ingredients

1. Chlorothalonil (e.g., Daconil, GardenTech Daconil)

A contact (non-systemic) fungicide with excellent preventive activity against dollar spot
Must be applied before or at first sign of disease; provides no curative activity on established infections
Apply every 7–14 days during high-risk periods
Widely available, affordable, and one of the most commonly used homeowner fungicides
Chlorothalonil fungicide — stock up before season starts

2. Propiconazole (e.g., Bonide Infuse, Banner MAXX)

Systemic triazole fungicide with both preventive and curative properties
Moves within the plant to provide internal protection
Effective application interval: 14–28 days
One of the best options when dollar spot is already established

3. Myclobutanil (e.g., Spectracide Immunox)

Triazole fungicide, widely available at retail stores
Good systemic activity against dollar spot
Apply every 14 days; rotate with chlorothalonil or other modes of action

4. Azoxystrobin (e.g., Scotts DiseaseEx, Heritage)

Strobilurin fungicide with broad-spectrum activity
Strong preventive activity; moderate curative
Apply every 14–28 days; rotate with triazoles to manage resistance

5. Iprodione (e.g., Chipco 26019, Bayer 26/36)

Dicarboximide fungicide with good dollar spot activity
Effective both preventively and curatively
Not always widely available in consumer markets; more common in professional products

Important: Fungicide Resistance

Dollar spot fungicide resistance is a genuine concern, especially on golf courses where fungicides are applied frequently. C. jacksonii has demonstrated resistance to multiple fungicide classes, including benzimidazoles, dicarboximides, and DMIs.

For home lawns, resistance is less common but still a consideration:

Always rotate between fungicide classes — never use the same product (or same class) consecutively
Avoid applying fungicides more frequently than the label recommends
Use cultural controls as the foundation — fungicides should supplement, not replace, proper lawn care

Sample Rotation Program for Home Lawns

Application	Timing	Active Ingredient	Class
1st	When 60°F days/50°F nights arrive	Chlorothalonil	Contact/Multi-site
2nd	10–14 days later	Propiconazole	Triazole (DMI)
3rd	10–14 days later	Azoxystrobin	Strobilurin (QoI)
4th	10–14 days later	Chlorothalonil	Contact/Multi-site

Continue as long as conditions remain favorable (typically through October in cooler regions).

Recovering From Dollar Spot Damage

Dollar spot typically kills individual grass blades but does not attack crowns and roots in the same way that summer patch or necrotic ring spot do. This means recovery is generally faster than for root-rotting diseases:

Apply a light nitrogen fertilization to stimulate active growth and fill in damaged areas
Mow frequently to remove diseased tissue and encourage lateral spread from healthy plants
If patches are large or bare spots remain after 3–4 weeks, overseed with a resistant grass variety using a nitrogen fertilizer at seeding to support establishment
Continue monitoring for recurrence — once dollar spot is established in a lawn, it tends to recur annually unless cultural practices improve

Dollar Spot on Specific Grass Types

Bermudagrass Lawns

Dollar spot is one of the most common diseases on bermuda lawns in the South and transition zone. Key management:

Maintain active growth with adequate nitrogen; dormant or slow-growing bermuda is extremely vulnerable
Apply fungicides preventively in spring as bermuda breaks dormancy if the disease has been a previous problem
Use thatch-control practices — bermuda builds thatch rapidly, and thick thatch worsens dollar spot

Kentucky Bluegrass Lawns

Dollar spot is most problematic in spring and fall on bluegrass
Blends with disease-resistant varieties show significantly less damage
Prioritize fall fertilization to build nitrogen reserves that reduce spring susceptibility

Fine Fescue Areas

Fine fescues are among the more resistant grasses to dollar spot. If you’re dealing with chronic dollar spot in a shady area, transitioning to a fine fescue blend may reduce the need for fungicide programs over time.

Conclusion

Dollar spot is ultimately a disease of stressed, under-nourished turf. The most powerful tool you have against it isn’t a fungicide — it’s a fertility program that keeps your grass growing vigorously and a watering schedule that minimizes overnight leaf wetness.

When cultural controls aren’t enough, a well-timed fungicide rotation using products like chlorothalonil and propiconazole will bring even severe outbreaks under control. Pair that with a thatch rake for annual dethatching, and a soil test to dial in your nitrogen program, and dollar spot can go from a season-long battle to a minor, manageable nuisance.

Know the hourglass lesion. Water in the morning. Keep your nitrogen up. And you’ll stay ahead of dollar spot all season long.