Root Decline / Take All Root Rot
Causal Agent
Gaeumannomyces graminis var. graminis
What is Root Decline / Take All Root Rot?
Root Decline is an ERI (ectotrophic root-infecting) fungal disease that can affect all warms season turf grasses but is a key pest of couch grasses. Root decline is also known as Take-All Root Rot.
The symptoms of root decline can be seasonally recurring and difficult to control.
What are the Symptoms of Root Decline?
Symptoms of root decline include:
-
Irregular shaped, chlorotic patches from 20cm to 1m in diameter. Patches once established continue to spread throughout the year and may enlarge to reach a diameter of 5m or more.
-
Patches of infected turf eventually die back with foliage turning tan to dark brown. Affected patches do not usually heal rapidly and the centres are invaded/ colonised by weeds.
-
New shoots may recolonise infected areas but soon become infected and die back.
-
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.
-
Less severely infected tissues often bear dark strands of mycelium oriented primarily parallel to the root axis.
Root Decline INFO SHEETTurfgrasses particularly susceptible to Root Decline are:
Warm season turfgrass, mainly Cynodon spp. and Couch grass
When does root decline occur?
General conditions that favour root decline are:
-
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
What can I do to manage or control root decline?
Turf management practices that can help control or reduce instances of root decline include:
-
Use acidifying fertilisers
-
Apply moderate to high levels of phosphorous, potassium and minor elements where these nutrients are depleted from the soil.
-
Apply biostimulants to trigger root recovery following infection.
-
Improve drainage of turf.
-
When liming apply the coarsest grades of lime to avoid rapid changes in pH.
-
Removal of diseases patches and re-sodding where small areas are affected.
-
Preventative systemic fungicide applications
