PACHYMETRA ROOT ROT SURVEY OF THE TULLY DISTRICT IN 2013

PACHYMETRA ROOT rot is a soil-borne disease which impacts all sectors of the Australian sugar industry. The disease attacks the root system of the sugarcane crop, affecting yields and leading to stool loss/shortened crop cycles, impacting the farming, harvesting and milling sectors. Increased extraneous matter and stools in the cane supply result in elevated soil levels, reduced crushing capacity and increased factory wear. Monitoring and management of the disease is therefore important to minimise effects on the crop, so bringing benefits to the whole value chain. A survey conducted in 2004 showed that Pachymetra root rot was widely distributed across the Tully mill area and that some crops were badly affected by the disease. A second survey undertaken in 2013, initiated by Tully Sugar Limited, sought to determine trends in disease incidence and to quantify the current effects of the disease. Crop resistance has shifted significantly in recent times with a change in varietal resistance associated with the smut epidemic. The results suggest that disease levels have escalated since the last survey, with spore levels rising by over 65%. Increases in severity were recorded in almost all districts. El Arish, Feluga and Lower Tully remain the worst affected. Financial losses from reduced yield were estimated at $5.5 m; this compares with just under $1.0 m in 2004. Better management of crop varietal resistance is recommended as well as the breeding of varieties with a greater level of resistance to the disease. Further surveys should be undertaken on a regular basis to highlight the success or otherwise of applied management strategies.