Common Native Insects and Diseases
Bark beetles are small black insects that feed just under the bark of stressed/dying trees. Signs include straight, horizontal feeding galleries, and small circular exit holes (about the size of a pencil point).
Sawyer beetles are large insects whose large cream coloured larvae cause a large amount of damage throughout the wood of a stressed tree. Signs are sawdust under the bark and large, round exit holes.
Armillaria root rot is a fungus that infects aspen, fir, maple, oak, pine and spruce. Infected trees can die from girdling at the root collar or killing major roots. Armillaria kills the cambium and outter layers of wood, leading to decay. Infected wood appears wet, yellows then whitens.
Balsam Fir single tree mortality
You may have noticed a large number of dead or dying individual fir trees in the landscape. Curious why?
The Forest Pest Management Group has been conducting surveys across the province over the past few weeks to better understand the cause and severity of the decline.
Rapid tree death has been observed at low impact levels (less than 0.5%) province wide (as well as through Vermont-New Hampshire-Quebec). Balsam fir is most affected in our area, but other conifers are also showing signs of stress.
The cause appears to result from a combination of climatic conditions (last summers drought, last winters big thaw) creating rapid water loss without replacement. When this occurs in spring, before the roots systems have thawed, a condition described as “Winter Drying” can occur. It may take months for some stressed tress to turn red as temperatures rise. The Forest Pest Management Group suspects that roots system depth, snow pack, soil composition, heavy winds etc. are contributing factor.
While the cause of die-offs is NOT an insect, stressed trees do become more susceptible to a variety of pests, so any number of insects may be present on the already dead/dying trees.
Native insects and fungi play an important role in decomposition and nutrient cycling in our soils, and at normal population levels, are nothing to be concerned over.
Changing climate and increased droughts are hard on many of our northern species. New Brunswick is towards the southern limit of balsam firs range, so is particularly susceptible to high temperatures and dry conditions in our area.