Pathogenicity of Neonectria fuckeliana on Norway Spruce Clones in Sweden and Potential Management Strategies

Abstract

Abstract:The fungus Neonectria fuckeliana has become an increasing problem on Norway spruce (Picea abies) in the Nordic countries during recent years. Canker wounds caused by the pathogen reduce timber quality and top-dieback is a problem for the Christmas tree industry. In this study, four inoculation trials were conducted to examine the ability of N. fuckeliana to cause disease on young Norway spruce plants and determine how different wound types would affect the occurrence and severity of the disease. Symptom development after 8-11 months was mainly mild and lesion lengths under bark were generally minor. However, N. fuckeliana could still be reisolated and/or molecularly detected. Slow disease development is in line with older studies describing N. fuckeliana as a weak pathogen. However, the results do not explain the serious increased damage by N. fuckeliana registered in Nordic forests and Christmas tree plantations. Potential management implications, such as shearing Christmas trees during periods of low inoculum pressure, cleaning secateurs between trees, and removal and burning of diseased branches and trees to avoid inoculum transfer and to keep disease pressure low, are based on experiments presented here and experiences with related pathogens.

Wood-inhabiting macromycete communities in spruce stands on former agricultural land

“…Neonectria fuckeliana is currently considered to be a threatening spruce parasite. Pettersson et al (2018) reported the pathogenicity of N. fuckeliana to spruce. They researched the growth process and virulence of N. fuckeliana on inoculated young spruces and found that the development of symptoms in 8-11 months after inoculation was mild and lesions under the bark were usually small.…”

The tree species matters: Biodiversity and ecosystem service implications of replacing Scots pine production stands with Norway spruce

“…Thus, the planting of spruce on pine soil types may result in maladaptation of the host tree and a higher risk of infection. The canker-causing fungus Neonectria fuckeliana is also becoming an increasing problem for spruce (Pettersson et al 2018), though it is unknown whether elevated risks will occur for spruce in this context.…”