Chemical compounds released by decay fungi may facilitate infection by Neonectria. Decay fungi breakdown wood polymers into constitutive monomers for absorption into hyphae by secreting wood degrading enzymes Neonectria use digestive enzymes during colonization and infection of bark tissue. A facilitative interaction has been suggested to exist between beech scale and Neonectria because the insect saliva contains digestive enzymes similar to those secreted by the fungus. Thus, it seems reasonable to hypothesize a similar interaction between one or both Neonectria species and decay fungi. These different groups of fungi primarily occur in separate tissues, except during sporocarp development when decay infections spread outward radially through the bark and subsequently longitudinally within bark. Because we used conk presence as an indicator of infection by decay fungi, it is reasonable to assume that bark tissue of affected study trees was colonized by decay fungi. Indeed, bark tissue axial to conks often was swollen and deformed (data not shown), another indicator of decay fungi within this tissue. Neonectria may, therefore, be capable of colonizing larger amounts of bark by augmenting its digestive enzymes with those secreted by decay fungi.