Armillaria novae‐zelandiae and other basidiomycete wood decay fungi in New Zealand Pinus radiata thinning stumps

Two studies were undertaken in a young New Zealand Pinus radiata stand to find a biological control agent for armillaria root disease caused by Armillaria novae‐zelandiae. Fresh thinning stumps were inoculated with saprophytic basidiomycete species as wooden dowel cultures or as homogenized aqueous mycelial suspensions, while all stumps were also inoculated with dowel cultures of A. novae‐zelandiae. After a period of between one and two years, no differences were found among test fungi in the percentage of Armillaria species isolated from stumps. However, inoculation of Stereum sanguinolentum as homogenate, and of Phlebiopsis gigantea, Sistotrema brinkmannii, Hypholoma acutum and Rigidoporus concrescens as dowel cultures, significantly increased their isolation incidence in comparison with stumps not treated by these species. Phlebiopsis gigantea, Resinicium bicolor and R. concrescens were also isolated with greater frequency nearer to their dowel inoculation points. Results suggest that P. gigantea and S. sanguinolentum should be included in further testing. However, a future trial is likely to be more effective if evaluation is directed towards the portion of the stump below the soil surface, particularly the root system.