Causal Agent:
Pythium spp.
Susceptible Turfgrasses:
Annual bluegrass
Creeping bentgrass
Bermudagrass
Identification:
Pythium Root Rot (PRR) symptoms can vary and often require lab analysis for definitive identification:
High-Density Bentgrasses:
Appears as reddish-brown, blue-gray, or purplish spots, resembling symptoms of wilt.
Older Bentgrasses:
Manifests as non-descript yellow, reddish-brown, or bronze-colored areas, indicating thinning and dying turf.
Root and Stem Activity:
The pathogen primarily affects roots and stems, with no visible foliar mycelium present.
Favourable Conditions:
Pythium Root Rot is caused by at least 30 different Pythium species, which infect turfgrass roots under the following conditions:
Soil Temperature Range:
Pythium species can infect across a wide range of soil temperatures, making PRR a versatile and persistent threat.
Excess Moisture:
Wet soil conditions are the primary contributors, often resulting from:
Frequent rainfall
Over-irrigation
Poor soil drainage
Environmental Stressors:
Symptoms are exacerbated by heat, low mowing, traffic, and shade, which weaken the turfgrass and increase disease severity.
Prevention Tips:
Drainage Improvements:
Enhance soil drainage through aeration or drainage installation to reduce excessive soil moisture.
Irrigation Practices:
Avoid over-irrigation and monitor soil moisture to prevent waterlogged conditions.
Stress Management:
Alleviate stress by raising mowing heights, reducing traffic, and minimizing shade where possible.
Soil Monitoring:
Use soil sensors to track moisture and temperature levels, making adjustments to mitigate disease risk.
Chemical Control:
Apply fungicides specific to Pythium species during high-risk periods to protect susceptible turfgrass.
Where Pythium root rot is a chronic problem, apply preventive fungicides on a 14- to 21-day interval when soil temperatures are above 65°F.
