Grey Leaf Spot

All turf species, especially Ryegrass and Kikuyu

• Grey Leaf Spot first appears as tiny, brown leaf and stem lesions, which enlarge rapidly into round to oblong spots.
• The largest spots may extend nearly across the entire leaf and become a bluish-grey in colour.
• Mature lesions are tan to grey with purple to brown borders.
• A halo or general chlorosis may occur around or near spots.
• The spots may be covered with a grey mycelium during periods of warm, humid weather.
• If disease is severe, the entire planting may appear scorched as if it were suffering from severe drought.

• Grey Leaf Spot is most severe during warm, humid weather.
• Temperatures between 25°C to 30°C.
• When turf grasses are stressed by various factors, including drought, soil compaction and excessive nitrogen.

• Avoid high nitrogen levels during mid-summer.
• Irrigate turf deeply and as infrequently as possible to avoid water stress.
• Allow water to remain on leaves for only a short period of time.
• Reduce thatch by verti-cutting.
• Prevent soil compaction.
• Avoid using herbicides or plant growth regulators when the disease is active.

Grey Leaf Spot is more severe in newly established planting with high nitrogen levels.