Long-term effects on other fungi are studied in biological and chemical stump treatments in the fight against Heterobasidion annosum coll

Abstract

The effects on mycoflora of Norway spruce stumps of biological and chemical treatments in the fight against Heterobasidion annosum coll. were investigated two yr after applications of these treatments. The biological treatments were Hypholoma fasciculare, Phanerochaete velutina, Vuilleminia comedens, Trichoderma harzianum and both the conidial suspension and culture filtrate of Verticillium bulbillosum; propiconazole was used as chemical treatment. Samplings were performed on 130 stumps, including controls with (C1) and without (C2) an autologous wood disk. Forty-nine fungal taxa were isolated, and most were Deuteromycetes. Trichoderma harzianum significantly reduced the number of taxa versus controls (three versus 25), while the other treatments showed more limited qualitative and quantitative effects. Cluster and correspondence analysis differentiated three groups of treatments: one including the three Basidiomycetes, V. bulbillosum and C1; one comprising propiconazole and C2; and one composed of the treatment with T. harzianum only. Because the same stumps already had been sampled one yr after treatments in a similar study, comparisons between data were possible and were very useful in the investigation of the temporal evolution of the effects of each treatment. Multivariate analysis showed that the strong effects of T. harzianum on stump mycocenoses increased over time. Transient effects were shown in most treatments (i.e., the three Basidiomycetes), whereas V. bulbillosum had the least impact on naturally occurring mycoflora.