Effects of biological and chemical treatments against Heterobasidion annosum on the microfungal communities of Picea abies stumps

Abstract

This study describes the effects of biological treatments with Trichoderma harzianum, Hypholoma fasciculare, Phanerochaete velutina, Verticillium bulbillosum and Vuilleminia comedens and chemical treatment with propiconazole against Heterobasidion annosum, on the microfungal communities of Picea abies stumps in a forest in the Alps of northwestern Italy. Immediately after felling, 20 healthy stumps per treatment were sprayed with the treatment preparations and their surface was protected with an autologous wood disk. The controls were 20 untreated stumps covered with an autologous wood disk. Another 20 untreated stumps were left without a wood disk to evaluate disk effects on the naturally occurring mycoflora. The microfungal populations were evaluated after one yr on 27 shavings from each stump. Fifty-seven fungal taxa were isolated, and most were Deuteromycetes. The number of species was generally significantly lower in the treatments respect to the control; T. harzianum treatment reduced the most species, V. bulbillosum the least. Multivariate analyses differentiated four groups of treatments: one comprising the treatments with the three lignovorous Basidiomycetes, one comprising the treatments with V. bulbillosum and the control, one comprising the treatment with propiconazole and the untreated stumps without the wood disk, and one composed of the treatment with T. harzianum only. These findings provide evidence that the pattern of fungal colonization of Picea abies stumps is influenced, sometimes greatly, by the treatments examined. T. harzianum and V. bulbillosum had the greatest and the least effect, respectively, on the naturally occurring mycocenoses.