Field trials with Armillatox against Armillariella mellea

Abstract

Abstract Field trials, in young conifer plantations, designed primarily to examine the effect of the proprietary fungicide Armillatox against root infection by Armillariella mellea, demonstrated that treatment of the soil with this material in the immediate vicinity of stem bases consistently reduced the activity of rhizomorphs present in the soil. On one site, in West Suffolk, with deep free-draining sandy soil, treatment with Armillatox caused the death of a substantial proportion of rhizomorphs in the soil without any evidence of significant phytotoxic damage to the roots of Scots pine and other tree species. On heavier soils in Alice Holt Forest, Surrey, the toxic effect of treatment on rhizomorphs was reduced, and with some species (notably Tsuga heterophylla and Abies grandis) significant damage to roots present in the treated soil was observed. In the Forest of Dean, again on heavier soil, considerable phytotoxic damage to the roots of Betula verrucosa was associated with the standard Armillatox treatment developed during these trials. However, the results suggest that protective chemical treatment against rhizomorph-initiated infection by A. mellea is feasible, and that a coordinated programme of research to examine the relative toxicity of a range of chemicals to rhizomorphs and to tree roots is warranted.