Scientific name
Pyricularia grisea (also known as Pyricularia oryzae)
Common Names
Grey Leaf Spot, Gray Leaf Spot
Grey Leaf Spot is a fungal disease that affects a wide range of turfgrass species, particularly kikuyu, buffalo grass and perennial ryegrass. It develops during hot, humid weather when leaf wetness is prolonged, especially in turf receiving high nitrogen applications or growing under stress. Symptoms begin as small brown spots that enlarge into oval or elongated lesions with grey centres and dark brown to purple margins. Severe infections can cause extensive leaf blighting, turf thinning and irregular dead patches.
Similar Diseases
- Leaf Spot (Bipolaris, Drechslera and Exserohilum spp.)
- Brown Patch (Rhizoctonia solani)
- Dollar Spot (Clarireedia spp.)
- Pythium Blight (Pythium spp.)
SCENARIOS AND SOLUTIONS
At the first signs of grey-centred leaf lesions: Apply Indigo AzoForce 250SC Fungicide 2.5L promptly to minimise disease spread and protect healthy turf.
On kikuyu and buffalo lawns during hot, humid weather: Apply Indigo AzoForce 250SC Fungicide 2.5L preventatively before extended periods of high humidity.
On sports fields and golf courses with recurring outbreaks: Include Indigo AzoForce 250SC Fungicide 2.5L in a preventative fungicide rotation during summer disease pressure.
In heavily fertilised turf showing rapid disease development: Reduce excessive nitrogen, improve airflow, and apply Indigo AzoForce 250SC Fungicide 2.5L to suppress disease activity.
References
https://www.syngentaturf.com.au/disease-foliage/grey-leaf-spot
https://www.au.envu.com/turf-and-ornamental-management/what-to-control/gray-leaf-spot
https://pnwhandbooks.org/plantdisease/host-disease/lawn-turf-gray-leaf-spot
