PYTHIUM BLIGHT

Causal Agent:

Pythium spp.      

Susceptible Turfgrass:

Mature cool and warm season turfgrass species. 

Symptoms: 

• Pythium 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, shrivelled 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.

 

Conditions Favouring Disease: 

• 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.

General Comments: 

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

   

Distribution:

Found in all states of Australia.

Management Tips: 

• Preventative fungicide program during high risk periods. 
• 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 fertiliser turf with nitrogen.
• Promote good light penetration into the turf canopy.
• Increase air circulation to speed the drying process of the turf.

Fungicidal control

The following products have label recommendation for Pythium blight control in Australia:  

Parameter	Subdue Maxx	Heritage Maxx
Mode of action	Systemic	Systemic
Optimum timing	When conditions favour disease development to first sign of disease	When conditions favour disease development
Dose rate	1.7-3.5 l/ha	6 l/ha
Ideal water volume	350-600 l/ha	350-600 l/ha

Refer to label for full details.

Suggested Programme

 

Contact Syngenta for assistance in creating a custom GreenSure Plan for your course.