Susceptible Turfgrasses:
Creeping bentgrass
Identification:
Pythium Root Dysfunction (PRD) symptoms emerge primarily during stress periods, such as heat, drought, or low fertility conditions:
Initial Signs:
Circles or irregular patches appear, initially resembling wilt or nutrient deficiency.
Progression:
Affected areas, up to two feet (61 cm) diameter, turn orange and eventually collapse to the ground.
Root Damage:
Roots become tan-colored, with soil easily falling away due to a lack of root hairs.
Favorable Conditions:
PRD is particularly problematic in creeping bentgrass putting greens less than 10 years old and is influenced by the following conditions:
Root Infection Period:
Infection occurs during fall to spring, with soil temperatures between 50°F and 75°F (10°C to 24°C).
Symptoms are usually absent above ground during this time.
Symptom Onset:
Severe root dieback occurs when soil temperatures exceed 85°F (29°C), triggering visible signs of decline.
Stress Amplifiers:
Low fertility
Drought stress
Low soil oxygen levels, often caused by compaction or excessive water retention.
Management Tips:
Soil Monitoring:
Use soil sensors to monitor temperature, moisture, and oxygen levels, helping to predict and mitigate risk.
Fertility Management:
Maintain balanced fertility levels, avoiding prolonged nutrient deficiencies that exacerbate stress.
Irrigation Practices:
Ensure consistent irrigation, particularly during high-risk periods, to prevent drought stress.
Aeration and Drainage:
Promote soil oxygenation through regular aeration and improve drainage to reduce compaction and waterlogging.
Chemical Applications:
Apply fungicides targeting Pythium spp. during high-risk infection periods to prevent root dysfunction.
Apply effective fungicides in the fall and spring on a 21- to 28-day interval when soil temperatures are between 50°F and 75°F.
