Grey Leaf
The turf disease gray leaf spot (GLS) is rare in Germany. When it does occur, it is usually found on heavily used sports turf, such as in soccer stadiums or on adjacent practice fields.
Clinical Presentation and Effects
In gray leaf spot, the grass blades are affected by gray leaf necrosis. The affected plant tissue dies off locally, causing:
photosynthesis is interrupted
substance transport in the leaf tissue no longer functions
The consequences can be serious:
In cases of severe infestation, the turf often dies off over a large area, making it necessary to partially or completely replace the lawn.
Ideal conditions for an infestation
For the disease to break out, high temperatures and prolonged leaf wetness must occur simultaneously.
Optimal temperature: 28–32 °C
→ at least 9 hours of continuous leaf wetnesssuboptimal temperature: 20–23 °C
→ Leaves must remain wet for 21–36 hours
Important:
Air temperature alone is not enough—what matters is the combination of heat and persistent moisture on the leaves.
Lawn areas that receive high doses of nitrogen are particularly susceptible.
Susceptible grass species
The following are particularly affected:
Perennial ryegrass
Lolium multiflorum
Tall fescue (Festuca arundinacea)
The following is not affected:
Poa pratensis (Meadow Bluegrass)
Survival and Spread
During unfavorable periods, the fungus survives as mycelium in dead plant material, such as that found in lawn thatch. As soon as conditions become favorable again, the disease can reoccur.
It spreads through:
Shoe soles
Tools
Wind
Water
Preventive Measures
To prevent a gray leaf spot infestation, we recommend:
A nitrogen supply tailored to needs
no over-fertilization
Avoid readily available forms of nitrogen
Optimize Irrigation
It's better to water early in the morning than in the evening
Keep the lawn as dry as possible
Mow regularly and collect the clippings
Do not reseed if there is an active infestation, so as not to encourage its spread