How to Spot and Treat Dollar Spot Disease in Lawns? - Plant Care Guide

Dollar Spot disease appears as small, straw-colored spots on your lawn, typically the size of a silver dollar. You can spot and treat Dollar Spot disease by identifying its distinct symptoms and then applying cultural practices or fungicides.

What Does Dollar Spot Disease Look Like?

Dollar Spot disease is a common lawn fungus that creates distinct symptoms, making it relatively easy to identify. Recognizing these visual cues is the first step in effective management.

Identifying the Spots

The most obvious sign of Dollar Spot is its namesake small, circular, sunken patches of dead grass. These spots typically measure 1 to 3 inches in diameter, resembling the size of a dollar coin. When multiple spots appear close together, they can merge, forming larger, irregularly shaped areas of damaged turf. The grass within these spots usually turns a straw-brown or bleached-tan color.

The Webbing Clue

One of the most defining characteristics of active Dollar Spot is the presence of mycelium. This is a fuzzy, white, cobweb-like growth that appears on the affected grass blades. You'll most likely see this webbing in the early morning when there's dew on the lawn, and it tends to disappear as the day warms up and the dew evaporates. This is a crucial diagnostic sign that confirms the presence of the fungus.

Individual Blade Lesions

Upon closer inspection, individual grass blades affected by Dollar Spot will show small, hourglass-shaped lesions. These lesions are usually light tan with a reddish-brown border. This distinct banding pattern on the grass blades helps differentiate Dollar Spot from other lawn diseases.

When Does Dollar Spot Occur?

Dollar Spot thrives in specific environmental conditions. It is most active during warm days (60°F to 85°F) and cool nights (below 60°F), especially when accompanied by high humidity or prolonged periods of leaf wetness. This often means late spring, early summer, and fall are prime seasons for this disease. Lawns that stay wet from dew, light rain, or improper irrigation are particularly susceptible.

What Causes Dollar Spot Disease?

Understanding the causes of Dollar Spot disease is essential for both treatment and prevention. This fungal disease, caused by the fungus Clarireedia jacksonii (formerly Sclerotinia homoeocarpa), thrives when certain environmental conditions and lawn care practices align.

Environmental Triggers

Dollar Spot fungus requires specific conditions to flourish:

• Prolonged Leaf Wetness: This is arguably the most critical factor. The fungus needs water on the grass blades for extended periods (typically 10-12 hours or more) to infect the plant. This often occurs due to:
  • Heavy morning dew.
  • Light, frequent watering that doesn't allow the grass to dry.
  • Poor air circulation that prevents dew from evaporating.
  • Slow-drying soils.
• Moderate Temperatures: The disease is most active when daytime temperatures are in the 60°F to 85°F (15°C to 29°C) range, with night temperatures dropping into the 50s°F (10s°C). This is why it's common in late spring, early summer, and fall.
• High Humidity: While related to leaf wetness, high atmospheric humidity contributes to the slow evaporation of moisture from grass blades.

Lawn Care Contributing Factors

Certain lawn care practices can inadvertently encourage Dollar Spot:

• Low Nitrogen Levels: Lawns that are deficient in nitrogen are particularly vulnerable. Nitrogen helps grass grow vigorously and recover from stress. Under-fertilized lawns are often the first to show symptoms.
• Compacted Soil: Poorly aerated, compacted soil restricts root growth and limits water drainage, leading to prolonged surface wetness.
• Poor Drainage: Areas of the lawn where water tends to pool or drain slowly will remain wet for longer, creating ideal conditions for the fungus.
• Excessive Thatch: A thick layer of thatch (dead organic matter between the grass blades and the soil) can hold moisture near the base of the grass blades, preventing them from drying quickly.
• Drought Stress: Paradoxically, while the fungus needs wet leaves, grass under drought stress can also be more susceptible to disease, as it's weakened and less able to fight off pathogens.

The combination of these factors creates the perfect environment for Dollar Spot to establish and spread in your lawn.

How Can I Prevent Dollar Spot Disease?

Preventing Dollar Spot disease is far more effective and less costly than treating an active outbreak. By implementing smart cultural practices, you can create a less hospitable environment for the fungus.

Smart Watering Practices

Proper watering is crucial for prevention:

• Water deeply and infrequently: Instead of light, daily sprinkles, water your lawn thoroughly to a depth of 4-6 inches. This encourages deeper root growth.
• Water in the early morning: Aim to complete watering before 10:00 AM. This allows the grass blades to dry completely before nightfall, reducing the duration of leaf wetness. Avoid late afternoon or evening watering, as this keeps the grass wet overnight.
• Check for dry patches: Use a Rain Bird 1804VAN Pop-Up Spray Head for efficient watering, ensuring consistent coverage.
• Address poor drainage: If you have areas that consistently stay wet, consider improving drainage through aeration or amending the soil.

Proper Fertilization

Maintaining adequate nitrogen levels is a key defense:

• Fertilize appropriately: Follow a balanced fertilization schedule based on your grass type and soil test results. Nitrogen is particularly important for strengthening grass and helping it recover. Avoid excessive nitrogen, however, as it can lead to other issues.
• Slow-release nitrogen: Using slow-release nitrogen fertilizers can provide a steady supply of nutrients, promoting consistent growth without sudden flushes that can weaken plants.
• Consider a Scotts Turf Builder WinterGuard Fall Lawn Food to ensure your lawn gets the nutrients it needs.

Mowing and Thatch Management

• Mow at the correct height: Mow your grass at its recommended height (usually 2.5 to 3.5 inches for most cool-season grasses). Taller grass shades the soil, promoting deeper roots and resilience.
• Regular mowing: Mow regularly to avoid removing more than one-third of the blade at a time, which stresses the grass.
• Remove thatch: Dethatch your lawn annually or biannually if the thatch layer exceeds 1/2 inch. Thatch removal improves air circulation and water penetration.
• Aerate compacted soil: Core aeration helps reduce soil compaction, allowing water and air to reach the roots more effectively, promoting healthier grass and reducing surface wetness.

Improve Air Circulation

• Prune trees and shrubs: If trees or shrubs shade your lawn and prevent air movement, consider pruning their lower branches to improve airflow and sunlight penetration.
• Avoid overcrowding: Don't plant too many trees or shrubs that will cast dense shade and restrict air movement over your lawn.

By diligently applying these preventative measures, you can significantly reduce the likelihood of Dollar Spot appearing in your lawn, maintaining a healthier and more resilient turf.

How Can I Treat Dollar Spot Disease Organically?

For those who prefer to avoid synthetic chemicals, several organic methods can effectively help treat and manage Dollar Spot disease. These approaches focus on improving turf health and creating conditions unfavorable for the fungus.

Cultural Control is Key

Organic treatment largely relies on perfecting your cultural lawn care practices, many of which are also part of prevention. When a mild Dollar Spot outbreak occurs, often simply adjusting these practices can halt its spread.

• Correct Watering: Re-emphasize deep and infrequent watering in the early morning. This is the single most important organic control measure. Allowing the grass blades to dry completely each day is paramount.
• Increase Nitrogen (Carefully): While often tied to prevention, a mild application of a nitrogen-rich organic fertilizer can help grass recover. Look for products like compost tea, alfalfa meal, or other slow-release organic nitrogen sources. The idea is to give the grass the nutrients it needs to outgrow the fungal damage. A soil test is highly recommended before adding any nitrogen.
• Improve Airflow: Use a leaf blower or a rake to gently remove dew from the lawn in the mornings. This simple action can dramatically reduce the duration of leaf wetness. Pruning overhanging tree branches can also help.
• Reduce Thatch and Aerate: These practices are just as vital for organic treatment as they are for prevention. A healthy soil ecosystem, fostered by aeration and proper thatch levels, will naturally resist disease.
• Mow Tall: Continue to mow at the upper end of your grass type's recommended height. Taller grass blades often mean deeper roots and a more resilient plant.

Beneficial Microbes and Compost Tea

• Compost Tea: Applying compost tea can introduce a diverse array of beneficial microorganisms to your soil and grass blades. These microbes can help suppress pathogenic fungi by competing for resources or directly attacking them.
• Mycorrhizal Fungi Products: Some products contain beneficial mycorrhizal fungi that can form a symbiotic relationship with grass roots, improving nutrient uptake and overall plant health, making the grass more resistant to disease.

Neem Oil

• Neem oil is a natural botanical extract that can act as an antifungal agent. It's often used as an organic fungicide and insecticide.
  1. Dilute: Mix neem oil concentrate with water according to product instructions.
  2. Apply: Spray the affected areas of the lawn thoroughly, ensuring good coverage of the grass blades.
  3. Timing: Apply in the late afternoon or early evening to avoid rapid evaporation and potential sun sensitivity during the hottest part of the day. Reapply as recommended by the product label, often every 7-14 days.

Consider a Garden Safe Fungicide3 Concentrate for an organic approach.

Organic treatment for Dollar Spot requires patience and consistent effort. It focuses on building a robust, resilient lawn ecosystem that can naturally fend off disease, making it a sustainable long-term strategy for Dollar Spot disease treatment.

How Can I Treat Dollar Spot Disease with Fungicides?

When cultural practices aren't enough or the Dollar Spot disease outbreak is severe, fungicides can be an effective treatment option. It's important to choose the right fungicide and apply it correctly for optimal results and to prevent resistance.

Types of Fungicides for Dollar Spot

Fungicides for Dollar Spot typically fall into two categories based on their mode of action:

• Contact Fungicides: These work on the surface of the grass, killing the fungus they come into direct contact with. They offer immediate protection but need to be reapplied more frequently, especially after rain or heavy watering.
• Systemic Fungicides: These are absorbed by the plant and move within its tissues, providing protection from within. They offer longer-lasting control and are often more effective at treating established infections.

Common active ingredients effective against Dollar Spot include:

• Propiconazole: A systemic fungicide widely used for turf diseases.
• Myclobutanil: Another systemic fungicide, often found in homeowner products.
• Azoxystrobin: A broad-spectrum systemic fungicide.
• Chlorothalonil: A contact fungicide that offers good preventative and curative control.

For a reliable option, check out Scotts DiseaseEX Lawn Fungicide.

When to Apply Fungicides

• Preventative application: If you have a history of severe Dollar Spot and consistent ideal conditions for its development, a preventative fungicide application might be considered. Apply before symptoms appear when conditions are favorable (e.g., late spring/early summer).
• Curative application: Apply fungicides at the first sign of symptoms. Early treatment is much more effective than waiting until the disease is widespread.

How to Apply Fungicides Safely and Effectively

1. Read the Label: This is the most crucial step. Fungicide labels provide specific instructions on application rates, mixing ratios, safety precautions, active ingredients, and target diseases. Always follow the label directions precisely.
2. Wear Protective Gear: Use gloves, eye protection, long sleeves, and pants when mixing and applying fungicides.
3. Calibrate Your Spreader/Sprayer: Ensure your equipment applies the correct amount of product. Over-application can harm your lawn, and under-application will be ineffective.
4. Apply Evenly: Aim for uniform coverage over the affected areas.
5. Timing: Apply when conditions are calm (no wind) to avoid drift. Avoid applying just before heavy rain, as it can wash away the product. Some systemic fungicides might require light watering after application to help them get into the soil and roots.
6. Rotate Fungicides: To prevent the fungus from developing resistance, it's highly recommended to rotate between fungicides with different active ingredients or modes of action. Don't use the same fungicide repeatedly.
7. Follow Reapplication Schedules: Note the reapplication interval on the label. Many fungicides require follow-up applications for sustained control.

While fungicides can be very effective in controlling Dollar Spot disease, they should be considered as one tool in an integrated pest management (IPM) approach. Combining fungicide use with improved cultural practices will yield the best long-term results and a healthier lawn.

How Do Environmental Factors Influence Dollar Spot?

Environmental factors play a dominant role in the development and severity of Dollar Spot disease. Understanding these influences allows you to anticipate outbreaks and adjust your lawn care strategies proactively.

Temperature and Humidity

• Moderate Temperatures: As discussed, Dollar Spot thrives in temperatures ranging from 60°F to 85°F (15°C to 29°C) during the day, with cooler nights. This combination creates an environment where the fungus can rapidly reproduce and infect grass blades.
• High Humidity/Prolonged Leaf Wetness: This is the absolute critical environmental factor. The fungal spores require a film of water on the grass blades for an extended period (typically 10-12 hours or more) to germinate and penetrate the plant tissue. This wetness can come from:
  • Heavy dew: Common during spring and fall mornings.
  • Light rain: Especially drizzly, overcast days that keep surfaces moist.
  • Irrigation: Improper watering that leaves grass wet overnight.
  • Poor air circulation: Prevents moisture from evaporating quickly.

Soil Conditions

• Nitrogen Deficiency: Lawns that are low in nitrogen are significantly more susceptible to Dollar Spot. Nitrogen is a vital nutrient for vigorous grass growth and its ability to repair damaged tissue. Under-nourished grass is simply weaker and less able to fight off infection.
• Soil Compaction: Compacted soil reduces the infiltration of water and air, leading to standing water on the surface and slower drying times. This directly contributes to prolonged leaf wetness.
• Poor Drainage: Similar to compaction, areas of the lawn with poor subsurface drainage will hold water, keeping the root zone soggy and, in turn, the grass blades moist for longer.
• pH Levels: While not as directly impactful as nitrogen, extreme soil pH (either too acidic or too alkaline) can stress grass and make it more vulnerable to disease. A soil test will help determine optimal pH levels for your turf.

Light and Air Circulation

• Shade: Shady areas of a lawn often stay wet longer due to reduced sunlight exposure for evaporation and potentially poorer air circulation. This makes turf in shaded spots more prone to Dollar Spot.
• Restricted Air Movement: Anything that impedes air movement over the lawn surface – dense trees, shrubs, fences, or even closely spaced turf in over-seeded areas – can create pockets of stagnant, humid air, increasing leaf wetness duration.

Understanding these environmental influences is crucial for comprehensive Dollar Spot disease management. By mitigating these factors through cultural practices, you can make your lawn much less inviting for the fungus.

What Grass Types are Susceptible to Dollar Spot?

While Dollar Spot disease can affect a wide range of turfgrasses, some types are more susceptible than others. Knowing your grass type can help you understand its inherent risk and tailor your preventative measures.

Highly Susceptible Grasses

• Bentgrasses (especially Creeping Bentgrass): These are extremely prone to Dollar Spot, which is why golf course greens, often composed of bentgrass, frequently battle this disease. Their fine texture and dense growth can trap moisture.
• Perennial Ryegrass: Another cool-season grass that is highly susceptible, particularly under stress.
• Fine Fescues (e.g., Chewings Fescue, Creeping Red Fescue): While generally low-maintenance, fine fescues can be quite vulnerable to Dollar Spot.
• Kentucky Bluegrass: While often resilient, Kentucky Bluegrass can still develop Dollar Spot, especially if nitrogen deficient or under stress.

Moderately Susceptible Grasses

• Tall Fescue: Generally more tolerant than fine fescues or ryegrass, but can still be affected, especially if conditions are ideal for the disease.
• Bermudagrass: A warm-season grass, Bermudagrass can get Dollar Spot, though often less severely than cool-season varieties.
• Zoysiagrass: Also a warm-season grass, it can be susceptible but often shows more resistance than bentgrass or ryegrass.

Factors Increasing Susceptibility Within a Species

Even within a susceptible grass type, certain factors can increase the likelihood of a Dollar Spot infection:

• Cultivar: Some specific cultivars (varieties) of grass within a species have been bred for better disease resistance. When choosing seed, look for disease-resistant cultivars.
• Stress: Any kind of stress on the lawn – drought, compacted soil, nutrient deficiencies (especially nitrogen), improper mowing height, or pest damage – weakens the grass and makes it more vulnerable to all diseases, including Dollar Spot.
• Age of Turf: Newly established lawns or recently overseeded areas might be more tender and susceptible.

If you have a highly susceptible grass type, it's even more critical to adhere strictly to all the preventative cultural practices, such as proper watering, fertilization, and thatch management, to minimize your risk of Dollar Spot disease.

What Other Lawn Diseases Resemble Dollar Spot?

When you see brown spots on your lawn, it's easy to assume the worst. While Dollar Spot disease has distinct characteristics, several other lawn diseases and issues can cause similar-looking patches. Accurate identification is crucial for effective treatment.

Brown Patch

• Appearance: Brown Patch typically forms larger, more irregular patches than Dollar Spot, ranging from 6 inches to several feet in diameter. The outer edge of the patch might have a smoky, purplish-brown ring (a "smoke ring") in humid conditions. Individual blades might have lesions, but they are usually larger and less hourglass-shaped than Dollar Spot.
• Conditions: Thrives in hotter temperatures (75°F-90°F / 24°C-32°C) and high humidity, often with excessive nitrogen.
• Key Difference: Size of spots (larger for Brown Patch), absence of the distinct hourglass lesion, and occurrence in hotter temperatures.

Pythium Blight (Grease Spot)

• Appearance: Starts as small, greasy-looking, dark spots that quickly spread and merge, turning water-soaked and then a cottony white as the fungus grows. In severe cases, it can look like an oil slick.
• Conditions: Favors very wet, poorly drained areas and hot, humid weather (85°F-95°F / 29°C-35°C).
• Key Difference: Greasy appearance, rapid spread, and occurrence in much hotter, wetter conditions.

Fusarium Blight (Necrotic Ring Spot)

• Appearance: Causes distinct "frog-eye" patterns, which are rings of dead grass with a healthy patch in the center. Rings can be anywhere from a few inches to several feet in diameter.
• Conditions: More common in compacted soil and stressed turf.
• Key Difference: Ring pattern of damage, larger size, and different individual blade lesions.

Drought Stress

• Appearance: Irregular patches of dry, straw-colored grass. Often appears first on elevated areas or compacted spots. Grass blades might curl or wilt before turning brown.
• Conditions: Occurs during prolonged dry periods with insufficient watering.
• Key Difference: No fungal signs (mycelium, specific lesions), usually no distinct circular spots unless irrigation patterns cause them. Grass feels brittle and dry.

Insect Damage

• Appearance: Depending on the insect, damage can range from irregular patches to thinning areas. Grubs, for example, cause grass to pull up easily like a carpet. Chinch bugs cause irregular brown patches in hot, sunny areas.
• Key Difference: Presence of insects, their droppings, or larvae (e.g., grubs), and different blade damage (chewed edges, yellowing). No fungal webbing or specific lesions.

How to Differentiate:

• Look for Mycelium: The white, cobweb-like mycelium of Dollar Spot in the early morning dew is a strong indicator.
• Inspect Individual Blades: The hourglass-shaped lesions on individual grass blades are unique to Dollar Spot.
• Observe Spot Size and Shape: The small, circular, silver-dollar sized spots are characteristic of Dollar Spot.
• Consider Environmental Conditions: Match the symptoms with the prevailing temperatures and moisture levels.

If you're unsure, it's always best to consult with a local lawn care professional or send a sample to a university extension service for accurate diagnosis. Proper identification is vital for effective Dollar Spot disease treatment.

What is the Role of Nitrogen in Dollar Spot Management?

Nitrogen fertilization plays a surprisingly significant role in both the susceptibility and recovery of lawns from Dollar Spot disease. Understanding its impact is crucial for effective management.

Nitrogen Deficiency and Susceptibility

• Weakened Turf: Lawns that are deficient in nitrogen are significantly more susceptible to Dollar Spot. Nitrogen is a fundamental nutrient for overall grass health and vigorous growth. When turf lacks sufficient nitrogen, it becomes weakened, stressed, and less able to naturally defend itself against fungal pathogens.
• Slow Recovery: Under-fertilized grass also recovers very slowly from any damage, including that caused by Dollar Spot. The existing spots will persist longer and potentially expand if the grass cannot grow new, healthy tissue quickly.
• Common Cause: Many homeowners unknowingly under-fertilize their lawns, or apply nitrogen unevenly, leading to patches of deficiency that become prime targets for the fungus.

How Nitrogen Helps

• Promotes Growth: Adequate nitrogen promotes lush, green growth. This helps the grass to "outgrow" the disease by constantly producing new, healthy blades, effectively replacing the damaged ones.
• Enhances Recovery: When a lawn has a good nitrogen supply, it has the resources to heal quickly, reducing the visible impact of Dollar Spot. The spots will shrink and disappear faster.
• Increased Density: Properly fertilized lawns tend to be denser, which can help shade the soil surface slightly, potentially reducing soil evaporation and influencing microclimates, though leaf wetness duration is still key.

Nitrogen Application for Dollar Spot Management

• Balanced Fertilization Program: The best approach is to maintain a balanced fertilization program throughout the growing season, based on your grass type and a soil test. This prevents severe nitrogen deficiencies.
• Moderate Nitrogen Boost: If you observe Dollar Spot and suspect nitrogen deficiency is a contributing factor, a light application of a quick-release nitrogen fertilizer can help the grass recover more quickly. However, this must be done carefully.
• Avoid Excessive Nitrogen: While nitrogen is good, too much nitrogen, especially in the wrong conditions (e.g., cool, wet weather for cool-season grasses), can lead to other fungal diseases like Brown Patch or Pythium Blight. It's a balance.
• Slow-Release Nitrogen: For long-term health and consistent nutrient supply, incorporating slow-release nitrogen fertilizers into your program is highly beneficial. They provide a steady feed, reducing the boom-and-bust cycle that can stress grass.

Nitrogen is a powerful tool in your Dollar Spot disease prevention and recovery arsenal. By ensuring your lawn receives adequate, but not excessive, nitrogen, you build a stronger, more resilient turf better equipped to withstand and recover from fungal attacks.

How to Assess Your Lawn for Dollar Spot Risk?

Proactively assessing your lawn's risk for Dollar Spot disease can help you implement preventative measures before an outbreak occurs. It involves observing your lawn and understanding its environmental conditions and care history.

Historical Risk Factors

• Previous Infections: Has your lawn had Dollar Spot in previous years? If so, the fungal spores are likely present in the soil, and your lawn is at higher risk when conditions become favorable again.
• Susceptible Grass Type: Do you have a highly susceptible grass type like bentgrass, perennial ryegrass, or fine fescue? Knowing this elevates your baseline risk.
• Neighborhood Issues: Are your neighbors dealing with Dollar Spot? Fungal spores can spread by wind, water, or even on lawn equipment.

Environmental Risk Factors

• Weather Patterns: Pay attention to forecasts. Extended periods of cool nights (below 60°F) combined with warm days (60°F-85°F) and high humidity (or prolonged dew periods) signal prime conditions for Dollar Spot activation.
• Dew Duration: How long does dew typically remain on your lawn in the mornings? If it persists for 10-12 hours or more, your risk is high. This can be due to:
  • Poor air circulation: Obstructions like dense shrubs, fences, or unpruned tree branches.
  • Shade: Areas that don't receive direct sunlight early in the morning.
  • Heavy thatch layer: Traps moisture at the soil surface.
• Drainage Issues: Are there areas in your lawn where water pools after rain or irrigation, taking a long time to dry? These spots are hotbeds for fungal activity.

Cultural Practice Risk Factors

• Watering Habits: Do you water frequently and lightly, especially in the late afternoon or evening? This is a major risk factor, keeping grass wet overnight.
• Fertilization Schedule: Have you neglected to fertilize your lawn, or has it been a while since its last nitrogen application? Nitrogen deficiency is a key weakness.
• Mowing Height: Are you mowing too short? Mowing too low stresses the grass and can make it more vulnerable.
• Thatch and Compaction: Do you have a thick thatch layer (over 1/2 inch)? Does your soil feel hard and compacted when you walk on it? Both hinder healthy growth and promote disease.

By honestly assessing these factors, you can get a clear picture of your lawn's vulnerability to Dollar Spot disease. This allows you to implement targeted preventative measures, such as adjusting your watering schedule, applying appropriate nitrogen, or performing aeration and dethatching, to reduce your risk and maintain a healthier lawn. Being proactive is the best defense against Dollar Spot.