Incidence of Armillaria root disease in karri regrowth forest is underestimated by surveys of aboveground symptoms

Summary

Intensive survey based on aboveground symptoms of Armillaria root disease underestimated true levels of disease by at least 20% and sometimes by up to 40% in high-quality karri regrowth stands. The results challenge the reliability of surveys based on aboveground disease symptoms. While most disease was established within the subdominant stratum, a very high proportion (30–60%) of the dominant trees were also infected. Within the study areas 15 distinct genotypes of Armillaria luteobubalina were identified. Individual genotypes existed as clones, with 2–3 clones per hectare. These factors need to be considered in stand management planning and yield predictions. A broader study, including lower-quality sites, is needed to determine whether these findings apply to all types of karri regrowth.

Keywords:

• root and butt rots
• disease surveys
• plant disease control
• karri
• Eucalyptus diversicolor
• Armillaria
• Western Australia