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'pruning'

Jan 23

Pruning Hacks

Posted to MMWD Blog: Think Blue Marin on January 23, 2015 at 9:09 AM by Ann Vallee

by Charlene Burgi

The past three weeks we have covered a throng of information about pruning whys and wherefores. Simply said, there are three reasons for pruning trees: Prune for your safety, the tree's health, and beauty.

Unfortunately, it is that time of year when blinders are needed to help alleviate the pain of seeing trees hacked by inexperienced hands that haven’t thought through the purposes of pruning. Sometimes I wonder if it is inexperience, lack of knowledge, or the attitude of "jest get 'r done." Either way, the outcome can be disastrous to the tree’s appearance, the tree’s health, and to anyone or anything unlucky enough to be around those trees in a storm.

 Pruning horror
 Pruning horror
I shudder when I see this attempt at pruning. The branch weighed too much to be removed with only one cut. That careless cut caused the heavy branch to rip into the bark and the cambium layer before departing from the body of the tree. There are no sealing properties left where the wood is exposed from the tear. This tree will, however, grow weak branch attachments from nodes where the bark is still attached at the cut. But like trying to attach something with the wrong type of glue, this type of growth will easily break off in high winds, becoming hazardous to anyone in the vicinity. Sadly this pruner did not consider safety, aesthetics, or the health of the tree!

With that said, let's set down some easy-to-learn ground rules about pruning:
  1. Always use the right tool for the job, as discussed in the blog three weeks ago.
  2. Never remove more than 1/3 of the tree's top growth in a year.
  3. Always make thinning cuts when reducing the height of a tree. That is, cut the entire limb back to another limb or trunk, rather than giving the tree a crew cut (also known as “topping”). Save the crew-cut look for hedges.
  4. When removing a heavy branch, make three cuts. The first cut is a small V undercut made away from the trunk to prevent the weight of the branch from ripping into the wood below. The second cut is made from above the limb and above the undercut (further away from the tree trunk) to remove the entire limb. The final cut is made next to the branch collar so the tree can seal properly. In time, a well-sealed tree wound will look like a doughnut. This link shows several methods for making good pruning cuts.
When it comes time to prune your trees and shrubs, if you don’t feel comfortable with the job, don’t hack. Hire a certified arborist, and check that they are experienced with the type of pruning you need. For example, some arborists do not specialize in fruit trees. Even if they use proper pruning cuts, they may inadvertently sacrifice your fruit production.

Also, remember to save some prunings to enhance the beauty of your home. Time your pruning to take advantage of quince, forsythia, pussy willows, and even fruiting tree twigs in bloom to make a beautiful statement in a vase in your home. And there is nothing better than saving fruit tree twigs to feed a BBQ fire. The fruity wood smoke will infuse the meat you are cooking. (Uncle Stan, I will never forget that turkey you barbequed years ago!)

Rebates: Five New Ways to Save

 video thumbnail
As a reminder, for a limited time MMWD is offering rebates up to $50 each for pool covers, hot water recirculating systems, organic mulch, laundry-to-landscape system components, and rain barrels. Get up to $250 for all five! To learn more, check out this video created by students at Ex'pression College in Emeryville, then visit marinwater.org/rebates.
Jan 16

Training for Fruiting Spurs

Posted to MMWD Blog: Think Blue Marin on January 16, 2015 at 9:22 AM by Ann Vallee

by Charlene Burgi

 Limbs crossing
 Crossing limbs in need of pruning
Pruning for fruit production can be confusing. Some trees bear their fruit on new—or “one-year” — wood, while other types require spurs older than three years before they bear fruit. To further complicate this issue, fruiting spurs on some trees only produce for five years while others continue to bear for 15 years. Since pruning can alter the outcome of fruit production, knowledge is key. Let's first look at general training techniques, then focus on procedures for encouraging maximum fruit production.

There are three approaches to shaping a fruit tree. The first method is to encourage a central leader. This creates a shape like a Christmas tree with a strong main stem and multiple smaller side branches, with the larger side branches on the bottom and the smaller branches toward the tip. This type of structure is commonly found in apple, pear, and cherry trees.

 Santa Rosa plum before and after pruning
Santa Rosa plum before pruning (top) and after (bottom)
The second training method, called modified leader, is also found in apple, pear, and nut trees. The tree has a strong central leader but—unlike the central leader method described above—here we encourage three to four strong main limbs of equal girth to the central stem. These lateral stems are best located randomly along the main trunk so they are not directly adjacent to each other. This method of training is excellent for controlling the growth of the tree and thus easier for harvesting the fruit.

The last method of training a fruit tree is known as the open center. Peach, nectarine, plum, apricot, and sour cherry trees best benefit from this type of pruning. When the tree is young, remove the central leader and encourage three to four main stems along the trunk to take on a rounded shape. Again, be certain to space the lateral branches along the trunk so none are adjacent to each other. This shape will allow plenty of light into the center of the tree.

When training a tree we’re obviously removing wood, and thus this is where our knowledge becomes critical for production. For example, figs, peaches, nectarines, and persimmons grow on new wood or first-year growth. When pruning these trees you are sacrificing your fruit. (The exceptions are shaping young peach and nectarine trees as described above; and removing crossing, diseased, or broken limbs, which holds true for pruning any tree or shrub.)

Apples, pears, cherries, plums, almonds, apricots, and walnuts form on three-year-old wood. These trees require pruning back two-thirds of the new growth. New spurs will grow on the second-year wood and fruit will form on the three-year-old wood.

All pruning should be done in winter when the sap is down in the tree. Apricots are the exception and are best pruned in July or August to protect the tree from a fungus called Eutypa (commonly known as gummosis). The fungal spores are easily spread by spring rains and can infect the tree through pruning wounds. Wait until after fruit harvest before pruning. If your tree already shows signs of gummosis (gummy oozing from the wood), cut at least one foot below the diseased wood during the summer months.

I found it interesting that the spurs on different varieties of fruit trees are productive for different numbers of years. For example, walnut tree fruit spurs can be viable for up to 15 years, while most almond fruit spurs are productive for five years. Knowing this, we can encourage new fruit spurs by pruning out old wood in a timely manner, allowing new wood to replenish the old before the tree’s production slows down.

Here's to bumper-crop years ahead!

Dec 31

To Prune or Not to Prune

Posted to MMWD Blog: Think Blue Marin on December 31, 2014 at 9:10 AM by Ann Vallee

by Charlene Burgi

January is always earmarked for pruning some of our trees, shrubs, and vines. But did you ever wonder why we prune? Or why some plants are pruned harder than others? And why some plants are better pruned in winter than other times of year? In the next few weeks we will unearth some answers.

This time of year always finds me rummaging through my books about pruning. I found it humorous that one pruning book suggested the best way to learn how to prune was to study the mistakes made by your neighbor! While I have seen some gross pruning cuts in my day, the nasty cuts didn't explain why or where to cut, only where not to cut. With that said, let this be the first note: Cutting in the middle of a branch just to shorten the height of a tree is criminal. It is like having a doctor amputate one of your limbs at mid length of a bone. The plant branch is no different. Always cut back to another connecting limb or joint.

Note two: We prune for several reasons. Plants can grow in directions that may not be acceptable in our gardens. For example, bougainvillea is a gorgeous plant that grows lethal thorns. A branch growing into the entryway to our front door would not be welcoming to anyone snagged by the plant’s errant growth. This type of pruning is considered directional pruning.

 narrow V crotch
A tight V-shaped crotch where
two limbs form can cause a tree
to split down the middle.
Other pruning techniques are for the general health of the plant. All dead wood should be removed, as well as the weaker of two branches rubbing against each other. Inspect the plant and remove the weaker or injured branch back to a stronger limb to allow needed light and air into the center of a plant. Check for diseased or injured branches and remove them before they spread the infection to healthy limbs.

General pruning to avoid future problems is yet another reason to grab a pruning tool. A tight V-shaped crotch where two limbs form can cause a tree to split down the middle as the tree ages. Remove the smaller of the two limbs to create a stronger tree. If you are in the market for bareroot trees (and now is the time for shopping for bareroot stock), look for a gentle curve, like a U, where limbs form.

We also prune to control the shape of a plant, to encourage or discourage growth, and to promote healthy flower and fruit production. In the upcoming weeks, we will go into more detail about these types of pruning. Timing is important and will explain why some plants such as quince, forsythia, and lilacs are better pruned after spring than in the middle of winter!

 Two types pruning tools
 Two types of pruning tools
Another major pruning concern is choosing the right tool for each job. A chainsaw works wonders on a large tree limb, but keep it away from roses! Hand pruners are perfect for small twigs, perennials, roses, and berry canes. Hedge shears need to remain in the garage when you’re doing any heavy pruning. Their job is specified in their name … shearing hedges only! Hand saws should be used for small branches, and lopping shears and pole pruners are required to remove limbs less than an inch and cuts that are too high to reach. Jack just reminded me that there are now gas and electric pole chainsaws that allow you to reach up to 10 feet into the tree for removing bigger limbs. Before you begin pruning anything, be certain the chains and blades are well oiled and sharpened.

Stay tuned for more technical details in the weeks to follow. Meanwhile, a very happy and healthy new year to all of you.