The rights, wrongs, and realities of pruning

pruning demonstration
Proper pruning enhances tree health and value. Photo: Andy Perleberg, Washington State University Extension.

Pruning trees produces lumber clear of knots, reduces the hazard of fire climbing into crowns, may decrease the transmission of certain diseases, and improves the aesthetic appeal of the stand. But have you ever found yourself shaking your head, wondering “Why can’t I get the pruning done?” Judicious pruning is like being for motherhood and against sin. We are all agreed on it. Why isn’t it getting done? (from The Tree Farm Family by Robert Treuer)

Many forest owners keep journals. A journal also can help you keep up with pruning needs. A journal does not need to be formal or complicated, and it is better than the shoebox method for recording expenses, income, and activities. Pruning entries probably start out like this:

July 14 –Holiday and vacations over. Bees don’t come out until 9 am. Kids and I can get in two hours of pruning! Started near Y-road. Billy found bees nest early. Went to river to slap some mud on the stinger. Jimmy reminds me about swim team in 20 minutes. Returned to house…

August 3– Misty and unusually cool for August. Great day for pruning! Started at Y-road (avoiding bees nest!). Boys will join after slopping hogs. Mom calls and says pigs let themselves out and are down on the railroad tracks…

Sept. 25– Early supper. No scheduled sports or band this day. Great evening for pruning! Billy and Jimmy like their new saws and eagerly go to work. Saw worked well while Billy and Jimmy used them. Must remember batteries for stereo next time. Mom calls and says dessert is ready…

There are no entries for the remainder of the year. Does this sound like your life? If not, congratulations for balancing family needs with your forest management objectives! If you do find yourself just not getting things accomplished, don’t lose sleep. While you were tending bee stings and chasing pigs, your trees kept growing and working for you.

Pruning is the most commonly implemented cultural practice by family forest owners. As mentioned, there are multiple reasons why people prune. Some prune for wood quality, some for risk reduction, and others because they like the way a pruned stand looks. Simply clearing a trail through your woods can open the door to activities and engagement. For whatever reason(s) you prune, it is important that you do it properly so that your objective(s) can be achieved.

This article is a compilation of practical experiences and ideas, contributed by family forest owners throughout Washington State. The purpose is to help you understand the basics of pruning, and to tell their story from a management planning context. For a good “Here’s how-to” guide to pruning, download the WSU Extension bulletin Conifer Pruning Basics for Family Forest Landowners, EB 1984.

Why prune trees

First, answer the question, What is your ideal condition? Most landowners want their forest to be productive, rich with wildlife, and aesthetically enjoyable. Pruning is compatible with these goals.

If you desire a pruned stand of crop trees with high quality wood, you’ll want to start early and conduct your pruning in combination with your thinning treatments – typically when tree diameter is about the size of a tuna can. If you prune before you thin, you risk investing time and money into pruning trees that will be removed in the future. As a general rule, you want to leave 50 percent of the total tree height in a live crown. Reducing the crown beyond this decreases the trees “energy factory,” or its ability to photosynthesize for maximum production and vigor.

Don Theoe, a forester and tree farmer in western Washington, says pruning to develop clear, knot-free wood is labor-intensive (usually requires two or three prunings over time), may be expensive if you hire out the job, and there is no guarantee that the clear logs you produce will fetch a premium when they sell. According to Theoe, pruning certification does exist in New Zealand, but domestic markets don’t generally reward for this practice. It is advisable to take photos and record these activities in business or tree farm inspection records, just in case this market does develop.

If your main reason for pruning is to reduce the risk of fire being carried into the crowns of the trees by ladder fuel, bear in mind that your goal is to reduce fuel and break the chain of radiant and convective heat. In this case, it is advisable to prune heavier and earlier in the stands development, achieving at least a 12 foot “lift” or clear bole. Remembering never to remove more than one half of the crown at one time, you may need to prune the tree at least twice.

Rhidian Morgan, a southwest Washington tree farmer said it best “The current markets do not reward our obstinacy in pruning. However, the original Douglas-fir pruning along a public road prevented an arsonist from starting a forest fire in late August. The device, recovered by a Washington State Department of Natural Resources (DNR) investigator, started the dry grass, but the fire could not catch any low dead branches. A neighbor reported the odd behavior, and a rapid DNR response controlled the grass fire. The investigation produced a culprit, but the pruning stopped the grass fire from rising into the trees.”

With the exception of fire protection, pruning is typically conducted before the limbs are greater than one inch in diameter. There is no need to dress the wound, because the tree will seal off with pitch and eventually wood will compartmentalize the site, creating clear wood beyond that ring. Pruning early before the limbs are large in diameter decreases the opportunity for bugs and cruds to enter, and will develop clear wood sooner. When pruning, never cut into the branch collar, as that will greatly enlarge the wound. Read more about how to prune correctly in the Oregon State University article Pruning to Enhance Tree and Stand Value

Finally, pruning can reduce infection and risk of exposure to white pine blister rust, a disease contracted by all five-needled pines which can kill the tree. The blister rust fungus enters the tree through the needles and travels down the branch where the symptoms are expressed by a orange-red canker on the trunk of the tree. It is practically impossible to eliminate blister rust from the stand, but pruning and/or thinning any signs of infected trees can greatly reduce the chance of leave trees becoming infected. For a complete article about white pine blister rust, read the University of Idaho publication: White Pine Blister Rust: Pruning Can Increase Survival

Mistletoe, an endemic parasitic plant to all conifer species, is also frequently pruned but rarely controlled.

When to prune

Pruning can take place anytime you can get an hour of work out of your teenager. Seriously, trees can be pruned at almost anytime of the year. The one exception is when the tree is actively growing (about mid-March to mid-July), when the bark and branch collars are soft and easily stripped off. Theoe prunes live branches from November to March when the trees are not growing; he prunes dead ones anytime. Morgan also prunes in fall and winter, and recently has timed pruning to take advantage of a Christmas greenery market. Dick Shellhaas, a northeast Washington forest owner, prunes following pre-commercial or commercial thins when the trees are dormant – he even prunes on snowshoes!

How to get pruning accomplished

Pruning right and wrong
Remove branches properly to minimize damage to the branch collar. (Source: Pruning to Enhance Tree and Stand Value, 1995)

If tennis champion Arthur Ashe is correct that “success is a journey and not a destination,” then he must have been a tree farmer. If you do the pruning yourself, you may never get it accomplished. Just as described in the journal example above, life happens. Theoe, Morgan, and Shellhaas are no exceptions – they prune for multiple objectives and are making progress. How people get the pruning done is where the greatest inconsistency occurs: Some use saws, some loppers. Some use ladders, some poles.

Because chainsaws can be awkward and because they cut so fast, most foresters advise not to use them for pruning trees. If chainsaws or motorized pole pruners are used, the operator should always have two feet on the ground. Never operate a saw when fatigued.

Quality saws are essential, so buy the best that you can afford, and keep them in good shape. Remove pitch daily. Remember a dull saw just makes you work slower. Good hand pruning saws can be purchased for about $20. A quality telescoping pole saw that can cut up to 18 feet high may cost as much as $200. Purchase saws from a forestry supplier instead of a big box store – this will ensure that you receive quality equipment that has been tested by forestry professionals. Theoe makes his own pole saws by attaching a saw blade to an ax handle, allowing him to reach up to ten feet. Safety equipment is a must, and includes a hardhat with goggles or safety glasses or screen, a long-sleeved shirt or coat, boots, gloves, and thick pants (a good northwest supplier is

Pruning work can be done by the landowner, or by hired help. Quality pruning crews are available, as are quality pruning supervisors. Theoe cautions landowners that if the job is done by hired help the workers need to be trained and closely supervised. Never prune more trees per acre than you would expect to have present at the time of the final harvest. Spacing of 20 feet x 20 feet provides 109 trees per acre.

Satisfaction guaranteed

Theoe, Morgan, and Shellhaas all agree that there is stress-relieving pleasure in pruning and being among a pruned stand. There is a sense of accomplishment with seeing instant results. And though the specialty market for pruned logs is virtually nonexistent, they continue to prune. At the end of the day, they gain confidence in knowing the risk of stand replacing wildfire is minimized. Of equal or greater importance, they like the way their forest looks.

First published in Northwest Woodlands, Fall 2008, Vol 24, No. 4

By Andy Perleberg, Washington State University Extension  509-667-6658
 For more information, see the PruningYourForest video series, a joint project with Washington State University Extension, Washington State Department of Natural Resources, and the Rural Technology Initiative UW/WSU