The black cottonwood, Populus balsamifera, native to the northwestern United States and western Canada are under a new threat from a deadly fungal disease. The black cottonwoods along coastal British Columbia are integral to the ecosystem; they provide habitat and forage for wildlife, prevent erosion and improve water quality, however, unless researchers can determine a method for control and eradication, the populations are at serious risk.
The fungus causing mass mortality among black cottonwoods, Mycosphaerella populorum, causes fatal lesions on tree stems, leaves, branches and trunks. The fungus uses its accessory genes to produce a toxin which causes the tissue damage. Until 2005, this fungus was contained in plantations and on research sites, the fungus broke out of one of these sites and spread.
Richard Hamelin, UBC professor and research analyst with Natural Resources Canada says, “”We are still in a stage we think we can contain it, our biggest concern is it might jump out and spread on native poplar black cottonwood.” Professor Hamelin warns that weather extremes and changes to the environment are probably contributing to the ability of this fungus to grow and spread, however, since the fungus is non-native, it is hard to quantify exactly what it will do. The research team is sequencing the genome of M. populorum in order to map the DNA and hopefully identify exactly how it is killing the trees. Once the mortality mechanism is isolated, methods for containing, controlling and eventually eradicating the tree disease can be formulated.