Pachymetra Root Rot

This disease was discovered in North Queensland in the early 1980s and is now found in all sugarcane-growing regions in Australia.

Pachymetra root rot is caused by a fungus-like organism known as an oomycete. The disease reduces yield, causes gappy ratoon crops and can lead to an increase of soil in the cane supplied to the mills.

What to look for

  • Pachymetra root rot attacks the large primary roots of the sugarcane plant, stunting its growth and reducing the anchorage of the plant in the soil.
  • Poorly anchored plants can tip out of the ground during strong winds or be pulled from the soil by a harvester.
  • The primary roots infected by the disease will become completely flaccid and only the epidermis or skin of the root remains intact.
  • Within the rotted root, the large spherical spores with large blunt knobs are produced in abundance.
Pachmetra root rot symptoms

Management

Pachymetra root rot can be managed by planting resistant varieties. Growers are advised to plant only highly resistant varieties if spore counts exceed 50-100,000 spores/kg of soil. An assessment for the spores of the fungus in the soil is available from SRA.