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Turf diseases are caused by fungi, bacteria, or environmental stressors, leading to discoloration, thinning, or death of grass in lawns and sports fields. Common diseases like brown patch and dollar spot are often exacerbated by improper watering, mowing, or nutrient imbalances.
Common Turf Diseases
- Symptoms: Small, round, sunken lesions with a bleached appearance. The lesions are usually about the size of a dollar coin and have a reddish-brown edge.
- Causes: Fungal pathogen (Sclerotinia homoeocarpa) thrives in warm, humid conditions.
- Management: Improve air circulation and reduce excess moisture. Apply fungicides if necessary and follow a proper fertilization program.
- Symptoms: Irregular, brown, sunken patches with a grayish or tan center and a dark brown edge. Patches can range from a few inches to several feet across.
- Causes: Fungal pathogen (Rhizoctonia solani) often caused by high humidity and warm temperatures.
- Management: Avoid over-watering and high-nitrogen fertilization. Improve drainage and increase air circulation. Apply appropriate fungicides if needed.
- Symptoms: White or gray powdery spots on grass blades, which can coalesce into a dense powdery layer. Grass may appear stunted or have a whitish cast.
- Causes: Fungal pathogen (Erysiphe graminis) thrives in shady, humid environments.
- Management: Improve light penetration and air circulation. Avoid excessive watering and apply fungicides if necessary.
Rust
- Symptoms: Orange, yellow, or reddish-brown pustules on the underside of grass blades. Grass may appear yellowed and weakened.
- Causes: Fungal pathogens (Puccinia spp.) thrive in warm, dry conditions.
- Management: Increase mowing frequency, avoid excessive nitrogen fertilization, and improve air circulation. Apply fungicides if necessary.
Leaf Spot
- Symptoms: Small, dark brown or black spots on grass blades, often with a yellow halo. Spots may merge to form larger areas of dieback.
- Causes: Various fungal pathogens (e.g., Drechslera spp., Bipolaris spp.) thrive in warm, wet conditions.
- Management: Avoid overhead watering and improve air circulation. Use disease-resistant grass varieties and apply fungicides if needed.
Summer Patch
- Symptoms: Circular patches of brown or yellowed grass with a green border. Patches may increase in size during hot, dry periods.
- Causes: Fungal pathogen (Magnaporthiopsis poae) often associated with high temperatures and drought stress.
- Management: Improve irrigation practices and avoid high-nitrogen fertilization. Aerate the lawn and apply appropriate fungicides.
- Symptoms: Roughly circular, reddish-brown spots or strreaks that suddenly appear. Presence of cottonball-like mycelium in early morning.
- Causes: Pythium aphanidermatum often occurs during wet weather in high maintenance landscapes that are frequently watered.
- Management: Avoid overwatering. Provide adequate soil drainange. Thin landscape plantings to promote good air movement across the turf. Avoid mowing and trafficking wet turf.
- Symptoms: Circular patches of dead grass with a dark brown or black ring around the edges. Patches can range from a few inches to several feet in diameter.
- Causes: Fungal pathogen (Ophiosphaerella korrae) often exacerbated by drought and high soil compaction.
- Management: Improve soil aeration and irrigation practices. Use disease-resistant grass varieties and apply fungicides if needed.
General Management Practices
Cultural Practices
- Proper Mowing: Maintain the recommended mowing height for your grass type. Avoid cutting more than one-third of the grass height at a time.
- Watering: Water deeply and infrequently to promote deep root growth. Avoid watering in the evening to reduce humidity.
- Fertilization: Follow a balanced fertilization program based on soil test results. Avoid over-fertilizing with nitrogen, which can exacerbate some diseases.
Soil and Lawn Health
- Aeration: Regularly aerate the lawn to reduce soil compaction and improve root health.
- Thatch Management: Manage thatch buildup by dethatching if it exceeds 0.5 inches. Excessive thatch can harbor pathogens.
Pest and Disease Monitoring
- Regular Inspection: Monitor your lawn regularly for signs of disease and address issues promptly.
- Record Keeping: Keep a record of any diseases and treatments to track patterns and effectiveness.
Disease Prevention
- Resistant Varieties: Choose grass varieties that are resistant to common diseases in your area.
- Sanitation: Remove and dispose of infected plant material to prevent disease spread.
Fungicide Application
- Correct Timing: Apply fungicides according to the disease lifecycle and recommended application rates. Follow label instructions for best results.
- Integrated Approach: Use fungicides as part of an integrated disease management strategy, combining cultural practices and resistance management.