First record of Entoleuca mammata in hybrid aspen plantations in hemiboreal Estonia and stand–environmental factors affecting its prevalence

Abstract

Entoleuca mammata [causing Hypoxylon canker (HC)] is one of the most serious pathogens that are colonising Populus species. The area of fast-growing hybrid aspen plantations has remarkably increased in northern Europe because of the high demand for woody biomass, but the prevalence of HC and the stand-related and environmental factors that favour its presence have rarely been monitored in such monocultural plantations. The presence of E. mammata in Estonia was proven by ITS sequence on hybrid aspen. Repeated monitoring after 4 years in 24 hybrid aspen plantations found that the share of visually damaged trees by HC increased from 0.6% (15-year-old trees) to 1.6% (19-year-old trees). The mortality rate of the infected trees during the 4 years was 100%. The probability of HC incidence was favoured by tree vigour and higher soil acidity. The higher susceptibility of more vigorous trees might be related to their trade-off between productivity and defence compounds. The share of trees with clear visual symptoms of HC can be considered marginal, but the aggressive nature of the pathogen suggests the need to extend the monitoring period, especially in recently thinned sites, and to expand the observations to native Populus tremula stands.

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