Current and future biotic risks for fast-growing broadleaves

Efficient land use requires efficient crops. Poplar and hybrid aspen have shown potential to meet these requirements. However, it has been demonstrated that production expectations are not always met and the reason for these failures can be associated with fungal decay in the roots and stems. Rot fungi may reduce the output from established plantations, both in the form of reduced wood fibre quality and reduced growth and vitality. In addition, global warming can in the future affect decomposition rates of fungi, including those in tree wood, making it less energy dense or even useless for bioenergy.  

Damage caused by biotic pests and pathogens seriously compromise the production potential and quality of biomass of fast-growing broadleaves. The PhD project will focus on: i) current fungal threats causing root and stem rot in birch, poplar, aspen and hybrid aspen and how to mitigate that damage, and ii) future threats on-the-horizon for birch production in Sweden, anticipating climate warming that may increase the incidence and severity of damage of Oomycete root pathogens, and possible introduction of exotic pests via global trade, which is on the rise, that would be devastating to birch.  

1) Root rot and spruce/birch admixtures:
Building on previous work which has shown infection in birch stumps post-thinning, the PhD student will investigate how do birch stump infections proceed i.e. contributing to secondary spread on roots?  

2) Diseases of aspen, hybrid aspen and poplar:
The PhD student will utilize material from a study where bore cores have been collected from trees in 20 stands across southern Sweden to examine fungal communities in sapwood and heartwood contributing to decay in trees; and possibilities for improving rust resistance screening with advanced phenotyping tools using infrared spectroscopy.    

3) Oomycete pathogens affecting birch in the landscape and nurseries:
The PhD student will investigate the distribution and diversity of Phytophthora and Pythium spp. to understand which are potentially hazardous for birch production now and in the future with climate warming. 

4) New threats:
Bronze birch borer is a quarantine pest for Europe and if introduced would likely have devastating consequences to birch populations especially in Scandinavian countries. The PhD student will assess the susceptibility of silver birch to bronze birch borer at birch provenance trials and common garden trials in Canada, in collaboration with tree breeding experts there.