Pythium Blight

Mature cool and warm season turf species

• Pythium Leaf Blight appears suddenly during hot, humid weather.
• Patches occur these patches can enlarge at a rapid rate.
• In the early morning, grass leaves appear water-soaked and dark in patches.
• When rubbed between the fingers, these water-soaked patches feel oily.
• Infected leaves become light tan to brown, shriveled and matted when dry.
• When humidity remains high, especially at night, the collapsed leaves become matted and covered with a fluffy white mass of fungal mycelium.

• Hot days (30°C - 35°C), humid or rainy weather when night temperatures are warm (above 20°C).
• Relative humidity exceeding 90% for at least 14 hours and a minimum temperature not falling below 20°C.
• Lush, dense grass growing under high nitrogen fertility is especially susceptible to attack.
• Turf areas with poor drainage and air circulation.

• When establishing a new area, provide for good surface and subsurface drainage.
• Avoid over-watering new plantings and avoid watering late in the day.
• On established turf water early in the day.
• Water infrequently and deeply.
• Removal of excessive thatch.
• Do not over fertilise turf with nitrogen.
• Promote good light penetration into the turf canopy.
• Increase air circulation to speed the drying process of the turf.

Excessive moisture is required before Pythium spp. can cause extensive damage.
Pythium Leaf Blight may be more severe in alkaline soils.