The summer warmth that draws golfers to the course is equally enticing to disease pathogens, which thrive in hot, humid conditions. Three all-too-common summer disease concerns for golf course superintendents (GCS), especially those located in the southern United States, are pythium blight, brown patch and dollar spot. Dollar spot appears in late spring and early summer, but lasts throughout both seasons. Here are a few tips to help understand your opponent better and make a preventive fungicide plan of attack:
Know your opponents.
Three turfgrass diseases commonly found infecting greens during periods of high heat and humidity are pythium blight, brown patch and dollar spot.
- Pythium blight is capable of killing a golf course green in less than 24 hours. As one of the fastest-moving diseases on golf courses, treating it quickly is critical to effective control. Even a small delay in response can cause substantial turf damage.
Pythium blight develops in high humidity conditions when night temperatures exceed 65°F in cool-season turf or 50°F for warm-season turf, and when leaves remain wet for more than 12 to 14 hours over several consecutive nights. Daytime temperatures above 85°F also encourage pythium blight development in cool-season turf, possibly due to increased stress. Excessive soil moisture and succulent foliar growth also favor disease development.
- Brown patch, caused by the Rhizoctonia spp fungus, can develop when nighttime temperatures exceed 60°F and leaves on the turfgrass remain wet for at least 10 hours. It is often severe when nighttime lows exceed 70°F and daytime highs are above 90°F. Other disease development factors include poor soil drainage, lack of air movement, cloudy weather and heavy dew. Management issues that encourage prolonged leaf wetness, such as overwatering or watering in late afternoon, can also increase disease severity.
- Dollar spot, an early season disease consideration that often begins in earnest in late spring, but is pervasive and can last all summer long, can cause permanent damage to turfgrasses. This disease develops when nighttime temperatures surpass 50°F, aided by the moisture caused by high humidity levels.
How to treat.
Preparation with preventive fungicide applications is always the best plan of attack when combating turf disease. A few tips:
- Limit high-moisture situations when possible and when ambient temperatures are high. Minimize leaf wetness and moisture with cultural practices such as using a leaf blower or other tool to dry heavy dew on grasses.
- Use a 10- to 28-day rotation of fungicides for preventive disease control, remembering to rotate modes of action and ensure adequate product coverage. Overlapping residuals with applications made every 14 days also ensures there are no gaps in disease coverage.
- Eagle® 20EW specialty fungicide acts as a curative solution for more than 15 turfgrass diseases. It also can be applied before turf conditions become hot and humid to preventively protect turfgrass from infection. When sprayed, Eagle 20EW migrates upward through plant tissue, translocating to new growth, providing continuous protection as new foliage appears for up to 28 days after an application.
- Fore® 80WP Rainshield® specialty fungicide provides the most cost-effective control of brown patch and black algae. It also protects against many other troublesome diseases. It is an ideal choice for summertime conditions when heat, humidity and heavy irrigation combine to create the most intense disease conditions of the year.
A combination of cultural maintenance and fungicide product solutions can help prevent and treat your most troublesome diseases.
Legals: ™ ® Trademarks of Dow AgroSciences, DuPont or Pioneer, and their affiliated companies or their respective owners. Arylex is a registered active ingredient. State restrictions on the sale and use of Eagle 20EW apply. Consult the label before purchase or use for full details. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Always read and follow label directions.