Ramorum Blight / Sudden Oak Death
Ramorum blight / Sudden oak death (RB/SOD) is...
...caused by the pathogenic wilt fungus Phytophthora ramorum and is thought to have been introduced from Asia. Much like Dutch elm disease, this exotic fungus causes wilting and dieback symptoms and ultimately leads to tree mortality.
RB/SOD is primarily spread by rain splash and wind, although P. ramorum spores possess the unusual ability to travel in waterways and therefore can potentially spread long distances. It is also spread by the movement of nursery plants, wood and soil.***Currently, ramorum blight has only been confirmed outside of nursery environments in California, Oregon and Washington. The fungus may not be able to survive in North Dakota due to susceptible host availability and climate requirements of the fungus.
Perhaps the most alarming feature of P. ramorum is its ability to exist on numerous other species without causing mortality. The fungus can be harbored on these species causing 'ramorum blight' of leaf tissue as it spreads to new areas. Though few of the known hosts are found in North Dakota, relatives of several of these species are found here (e.g. maples, oaks, rhododendron), highlighting the potential of the fungus to be introduced to our area.
Early detection of P. ramorum is essential for its control. Detection and treatment methods are continually being improved and strict monitoring and regulation of nursery materials is a focus of controlling the spread of RB/SOD.
Why should we be concerned about RB/SOD in North Dakota?
- Oak species are commonly planted as landscape trees in urban and rural settings.
- Oak is one of the few species that grows well in our state.
- Oak wood is valuable as lumber and is an excellent source of firewood.
- Wildlife populations rely on acorns as a valuable food resource.
More information about sudden oak death: www.na.fs.fed.us/sod/