Home > Syngenta offers inputs on grass diseases

Syngenta offers inputs on grass diseases

Supplier News

Syngenta  relates that a strange patch-like disease known as Kikuyu Yellows had appeared one summer in many areas of Australia and South Africa. The disease is believed to be caused by a primitive water mold known as Verrucalvas flavofaciens. Optimum growth occurs at 30°C (air temperatures) but growth of fungus can occur between 15 to 37°C. Associated with primitive water molds, wet conditions are often associated with the disease.

The fungus attacks the root system, causing a blackening rot appearance. Die-back of the root system can occur followed by chlorotic leaf symptoms. The symptoms may appear as small circular areas that can rapidly “grow” into large, several metres in diameter. This disease appears to be host-specific, attacking only kikuyugrass.

Culturally, symptoms occur try to promote growth through proper fertilization especially at this time. The use of ammonium sulfate as a nitrogen source has shown some medicinal properties that enhance turf recovery. Chemical control strategies are not fully understood and field evaluations continue.

The symptoms that appear as large circular patches are believed to be Kikuyu Yellows. This picture was taken toward late spring in Australia.

Rapid blight (pathogen: Labyrinthula terrestris) can occur on winter grass (Poa annua) or creeping bentgrass greens. Symptoms appear as irregularly shaped patches of yellow or brown turf ranging from 5cm to 2m in diameter.

Rapid blight outbreaks are associated with dry periods in the autumn and spring. This disease is predominantly associated with high soil salt or high salt in irrigation water. Creeping bentgrass or winter grass growing on soils with salt readings above 2.7 dS m-1 (Saturated Paste Extraction Method 1:1) are predisposed to this disease.

Frequent leaching needs to be done this autumn to reduce salt levels.

Newsletter sign-up

The latest products and news delivered to your inbox