Root Decline

Causal Agent: Gaeumannomyces graminis var. graminis

Susceptible Turfgrasses: Warm season turfgrass, chiefly Cynodon spp.

Symptoms

• Irregular shaped, chlorotic patches from 20cm to 1m in diameter.

• Patches once established continue to spread throughout the year.

• Roots, rhizomes and stolons turn off white to dark brown in colour.

• Dark black hyphae can be visible on root tissue as the fungus begins to colonise the root system.

• Root length and density is compromised as roots die off and become black.

• Patches of infected turf eventually die back with foliage turning tan to dark brown.

• New shoots may recolonise infected areas but soon become infected and die back.

• Patches may enlarge to reach diameter of 5m or more.

• Affected patches do not usually heal rapidly and the centres are invaded/ colonised by weeds.

• Less severely infected tissues often bear dark strands of mycelium oriented primarily parallel to the root axis.

Conditions Favouring Disease

• Generally more active in spring and autumn months.

• Has a higher tolerance to warm temperatures (>25°C) than Take All Patch.

• Greatly enhanced on turfgrasses grown in soils with high pH.

• Increasing acidity tends to suppress this disease.

• Soil conditions favouring the disease include, light texture, low organic content, low or unbalance fertility, soil pH above 5.5.

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