Fumigation of regrowth karri stumps with metham-sodium to control Armillaria luteobubalina

Summary

The use of metham-sodium as a possible control agent for armillaria root disease was studied on 13-year-old karri (Eucalyptus diversicolor) regrowth stumps. As a consequence its effect on colonisation by wood decay organisms was also examined. Armillaria luteobubalina-infccted stumps, with volumes of about 2000 cm³ (11–12 cm diam.) and 8000 cm³ (21.5–23.5 cm diam), were treated with 500 ml of metham-sodium and examined after 3½ years. Control stumps with volumes of about 4000 cm³ (16–17 cm diam.) were not treated. Compared to untreated stumps, the volume of uncolonised wood and advanced decay was significantly greater in metham-sodium treated stumps. The volume of stump colonised by A. luteobubalina was lower in metham-sodium treated stumps than in untreated stumps. In stumps with a volume of 2000 cm³, treatment with metham-sodium eliminated A. luteobubalina from 40% of the stumps and enhanced colonisation by white rot organisms, including an unknown species which colonised 45%-60% of the volume of the stumps in which it occurred. The use of fumigants to control armillaria root disease in regrowth forests is, however, very labour intensive and costly, and it creates health and safety issues for the operator. It is considered not to be a practical option.

Keywords:

• plant disease control
• plant pathogens
• fungi
• stumps
• fumigation
• metham-sodium
• Armillaria
• Eucalyptus diversicolor