The Pythium Problem in Turf
Pythium root rot is a destructive disease that affects both cool- and warm-season turfgrasses on golf course putting greens, where turf is maintained under intense environmental and mechanical stress. Cool-season species like creeping bentgrass and annual bluegrass are especially susceptible, while warm-season grasses such as bermudagrass and zoysiagrass are also at risk. Pythium root rot compromises root integrity and limits the plant’s ability to absorb water and nutrients, leading to rapid turf decline if left unmanaged.
Symptom Development
Symptoms of Pythium root rot can appear as uneven turf decline, general thinning, and a lackluster, chlorotic appearance that usually appears in irregular patches. Affected turf may also exhibit a bluish-gray hue and rapidly collapse under environmental stress, despite adequate moisture. Roots appear dark, greasy, and are easily sloughed off, revealing weakened or entirely decayed cortical tissue. Patchy turf decline often begins in low-lying or poorly drained areas and expands outward, particularly during cool, wet periods.
Environmental Conditions Favoring Disease
Pythium thrives in cool, moist soils, especially during spring and fall transition periods. Overwatering, cloudy weather, and poorly drained soils create the perfect conditions for disease infection and proliferation. Root zones that remain excessively moist for prolonged periods are especially susceptible. For warm-season grasses in particular, warm and humid spring conditions combined with prolonged soil saturation are ideal for disease development. Nighttime temperatures above 68°F, particularly when combined with heavy dew or rainfall, also elevate risk.
Cultural Control Strategies
Improve Drainage: Address poor surface and internal drainage to avoid saturated root zones. Persistent soil moisture is one of the primary drivers of Pythium diseases.
Increase Ventilation: Use high-powered fans, prune trees, or open canopy edges to promote airflow, reduce humidity, and dry out playing surfaces—particularly in shade-prone greens.
Aerify and topdress: Regular core aeration reduces compaction and thatch—both of which harbor Pythium. Manage organic matter and enhance water movement throughout the profile to prevent water-logged conditions.
Preventative Fungicide Program for Warm and Cool-Season Turf
Although visible symptoms and turf damage from Pythium root rot are usually not apparent until summer stress conditions, prevention of disease development and infection must begin in the earlier spring months. It is important to have an established fungicide program that includes rotation of different modes-of-action. Because the disease resides in the root zone, it is important to water in with at least 1/8” irrigation to move the active ingredient downward. Fungicide programs should begin in the spring when soil temperatures are consistently at or above 65°F.
Additional products may be added as needed for additional disease control throughout the year. Refer to the product label before use for all directions and restrictions. 1Fosetyl-Al 80 WDG is not compatible with certain products, refer to label for specific compatibility and use directions.
Quali-Pro Products Perfect for your Pythium Program
Gateway: Powered by cyazofamid, the trusted solution for fast, effective control of Pythium root rot, delivering targeted protection where your turf needs it most.
Strobe 2L: Enhances the control of Pythium root rot while reducing resistance risk and broadening disease protection for other key diseases like anthracnose, brown patch, fairy ring, leaf spots, and large patch.
Fosetyl-Al 80 WDG: Delivers exceptional summer stress protection by stimulating plant defense responses and enhancing turf vigor, while its unique mode of action supports resistance management and strengthens any Pythium control program.