Long-term effects of mechanized stump treatment against Heterobasidion annosum root rot in Picea abies

Abstract

Airborne Heterobasidion annosum (Fr.) Bref. sensu lato infections can be controlled by winter thinning or by mechanically spreading urea or Phlebiopsis gigantea (Fr.) Jülich spores on stump surfaces during summer thinning operations. The long-term outcomes of these control methods when applied as part of the conventional forest operations are unclear. We studied the rot incidence and population structure of H. annosum in plots of Picea abies (L.) Karst. thinned in winter or thinned in summer with and without treatment of the stumps. Plots were distributed among 11 stands in Sweden representing two different land use histories: forest and agricultural. After 13 years, the effect of stump treatment on rot incidence was only evident in stands on former agricultural land. In stands planted on former forest land with higher levels of preexisting rot than on former agricultural land, the expansion of preexisting genets of H. annosum might have masked the effects of stump protection. In former forest land, unprotected summer plots showed a greater diversity of H. annosum genotypes and a smaller number of trees infected by each genet than in protected plots, suggesting that protection treatments prevented the establishment of new genets, which may result in a reduced rot incidence in the future.

Adaptation to Climate Change in Swedish Forestry

“…[54], but milder winters would also increase the length of the period the fungi are able to spread and infect new stands [55]. As new infections occur through the surface of newly-cut stumps, prevention through stump treatment will be increasingly important in the future [56]. One way to limit rot infection and development in already-infected stands is to manage forest with a fewer number of thinnings and shorter rotation periods [57].…”

Reaction zone and periodic increment decrease in Picea abies trees infected by Heterobasidion annosum s.l.

“…The experiment had a bi-factorial split plot design Oliva et al, 2010). The first experimental factor was the history of the stand.…”

“…Wood cores were inspected regularly, and the presence of H. annosum colonies was noted. A colony of H. annosum per tree was transferred into a new plate, and together with isolates obtained from stumps and dead trees, the population structure of H. annosum in the sampled plots was studied in Oliva et al (2010) by somatic compatibility tests (Stenlid, 1985). Species identification was performed by pairing the isolates with homokaryon strains belonging to the species H. parviporum and H. annosum s.s. and confirmed by taxon specific competitive priming-PCR (TSCP-PCR) following Gonthier et al (2003).…”

“…Jülich on the stump surface, thus subsequent H. annosum airborne infections are out-competed. Recently, the long-term effect of protection treatments has been demonstrated (Oliva et al, 2008(Oliva et al, , 2010. Good estimates of the detrimental effects on H. annosum infection are required in order to demonstrate the economic viability of stump treatment (Möykkynen et al, 1998(Möykkynen et al, , 2000Pukkala et al, 2005;Thor et al, 2006).…”

“…On forest land, the trees were already decayed before the thinning, and as opposed to agricultural land, no differences between the treatments were observed. The population structure of H. annosum in 2008 suggested that most of the rot could be ascribed to infections originating from preceding rotations, thus trees had been probably decayed for more than 13 years (Oliva et al, 2010). Nitrogen addition due to urea treatment of the stumps could have an effect on tree growth.…”