- Written by Kevin R. Lee Kevin R. Lee
- Published: 11 January 2020 11 January 2020
While the eastern forest enjoys at least 15 species and the cold hard west maybe 3 or 4, the chinook belt in Alberta can claim only one hardy species. The northern red, the pin and the white can be found in Edmonton, Saskatoon and Winnipeg, and perhaps other areas, but in Calgary we have the bur oak. The bur is an eastern forest tree with a westward bent. Given enough time it will find its natural western boundary somewhere in the foothills of Alberta. It may take another 50,000 years. For now we are very happy to have even one of this much loved genus.
Anyone who has driven the prairie eastward to Winnipeg has seen the thick beautiful stands that start to occur at about the Manitoba-Saskatchewan border. For now this is the limit of westward expansion.
The bur oak, Quercus macrocarpa, is a beautiful tree, single stems and like a little colt in its adolescence. It soon thickens up to a full wide crown on most trees at about the 25-year mark. Large, deep jade green, deeply lobed leaves are a characteristic. With these classic oak leaves it is easy to identify this tree.
The bur oak has a few insect problems, none of them life threatening. Lace bugs are beautiful creatures that look like little flat space ships. Heavy lace bug feeding produces a mottled look with many off-color tiny whitish spots on the upper leaf surface. No serious damage is caused by lace bugs.
There are a number of small harmless wasps that associate with the bur oak, usually forming strange woody growths, galls. Some of these form on leaves, some on small twigs and stems. None do any significant damage to their hosts.
The rough bullet gall wasp is one of these, and clusters of small half-inch woody "bullets" along small stems is a sure identification. Another is oak leaf galls, which are small wood-like galls formed on the leaves themselves.
The bur oak is one of only two tree species in this area that form a tap root, identified as a large main root and if possible penetrating farther into the soil than the lateral roots. The other tree is the Russian olive. These tap roots are very important when considering transplanting either of these trees, not recommended.
With regard to pruning, it's usually unnecessary; remove deadwood if it occurs.