Posted 3/15/01 Master Gardener: by Jerry Vitalis, Chisago County Master Gardener More on Pruning Trees Last week I wrote that fruit growers would be out pruning apple trees by the end of February. Well, with the cold weather and the mounting snow depth in the orchards, pruning may be delayed. Remember that fruit trees should be pruned by April 15. Hopefully, the snow will be gone by that time. Master Gardeners, as well as the Extension Office, receives many calls each spring concerning the best time to prune different varieties of trees and shrubs. Check for winter damage as soon as possible and plan accordingly. Most deciduous (non-evergreen) trees and shrubs, should be pruned in late winter, about mid-February to mid-March, depending on the weather. Spring pruning of sap producing trees, such as maples, produce a heavier flow of sap that may be unattractive. However, it will not harm the tree. The boxelder is in the maple tree family and it seems that you can prune it anytime without fear of killing it. In fact, if you know how to get rid of the boxelder, let me know. Oak trees can be pruned until April 15 and then not until after July 1 to prevent oak wilt. Oakwilt is the name of a fungus disease that effects oak trees. One way the fungus travels is through the air by the picnic beetle, which attacks a fresh wound. The other way the fungus spreads is underground. After the first oak dies, other oaks of the same species contract the disease, via the root grafts. This is the way that most oaks are affected. Rarely will white and red oaks form root grafts. If you notice recently dead or dying oaks, call the Extension Office at (651) 674-4417. Evergreen plants, such as pines, spruce, junipers and arborvitae, are usually pruned in late spring or early summer as new growth emerges. Spring flowering, deciduous shrubs that bloom on last years wood (forsythia, lilacs and mock orange, for example) should be pruned right after they finish blooming because they start setting flower buds for the next year within a month or so of flowering. These shrubs can also be pruned in late winter, but remember you will be removing some flower buds at the same time. The birch tree is one of the few species of trees that should not be pruned until late summer or early fall. August is probably a good time to start pruning the birch in order to avoid exposing the tree to the bronze birch bores, which is a very nasty insect. You may want to keep this article for future use during the coming growing season. Remember that you can always call the Extension Office is North Branch at (651) 674-4417. Also, remember the Bonanza on Saturday, March 24 at the Fairview Medical Center in Wyoming, MN. Look for updates on this great event that you are encouraged to attend. ©Post Review