blooming flowers climber in tree to prune beneficial mushrooms close up of lady bug on leaf japanese maple being pruned
Current Issue - Spring/Summer 2013

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The Arbor Advisor
> Spider Mites
> Drought Stress to Trees & Shrubs
> Summer Ornamental Pruning
> Surgery on Signature White Oak
> Featured Tree: Katsura
> Planting with Friends of Trees
Spruce spider miteSpruce spider mite

Microscopic Pests Cause Damage During Summer

Spider Mites are an almost microscopic pest that can account for a great deal of plant damage during the summer months in our landscapes. There are a wide variety of spider mite species, each feeding on specific plant material.

As their name implies, spider mites have eight legs and look somewhat like spiders. They damage plants by sucking the fluids from evergreen and deciduous plants alike. Mites have multiple generations each year so feeding damage can occur in a short time. Some mite species over-winter in egg form (making dormant treatments an effective preventative treatment for potential summer feeding damage) and can begin to feed in the spring once temperatures trigger egg hatch.

Newly-emerged young and adults feed throughout the summer causing the stippling or bleaching of the foliage. When populations are at their peak, dense webbing can be seen covering the affected plant.

Mites prefer dry, dusty conditions so in the early stages of feeding damage, hosing off your plant once a week with water can help to suppress their populations. Once feeding damage becomes visible the mite population is very high and you will need to treat quickly. We have a number of treatment and program options available to control your mite problems.

Tips for Summer Ornamental Pruning

Our great spring has provided wonderful growing conditions for our plants to put on a tremendous luxuriant growth. But as we look around the garden we quickly realize we need to do something to tame the jungle. Summer is the best time for pruning many of your flowering and ornamental trees and shrubs. The bloom is complete and the new growth is now hardening off as spring ends and summer starts.

Flowering and ornamental trees and shrubs, such as rhododendrons, azaleas, dogwood, lilac, flowering cherry and plum, Japanese maple, small ornamental conifers, and hedges, just to name a few are better pruned after the spring flush of growth.

Benefits include:

This way you get to enjoy the bloom you have waited all year for
Prepares the tree or shrub for bloom set for the following year.
Has a dwarfing growth affect on specimen trees in limited growth locations
Re-gains control and opens up branch structure for better visual aesthetics

When summer pruning:

Crown clean the interior of the canopy by removing deadwood and crossing branches working from the inside toward the outside.
Crown thin the outer portion of the canopy to allow for more light penetration to the interior, usually not more than 15 – 20 % annually.
Crown Raise or Crown Reduce to provide clearance around obstacles in the landscape.

Is your pruning job is just too big to tackle? The hedge is too tall and wide for you to trim? You tremble with fear at the thought of your spouse using power equipment? Call the professionals at Collier Arbor Care. Our certified Arborists will efficiently tackle your biggest job and turn those out of control plants into living works of art.

Dry and shriveled leaves are indications of drought stress.

Drought Stress to Trees and Shrubs

Drought is a meteorological term for lack of precipitation over a long period of time. With our traditionally dry summers, drought is an issue through the months of June to mid October. This Spring we also had a longer than normal period without precipitation.

Plants can suffer from drought stress any time they receive less water than they need. Water is essential to the normal maintenance and growth of all plants. It moves into the plant roots from the soil and is transported up through the water- conducting vessels in the branches, stems, and foliage to all the plant cells. Eventually, the water evaporates from the tiny breathing pores in the leaves.

When plants don’t receive adequate water, the water pressure in the cells can drop. Plants will begin to wilt, stop growing, become discolored and stunted, drop their leaves and fruit, or eventually starve and die. Other visible signs are discoloration to the edges of the leaf and the size of the leaf can be smaller than normal. Also, insect and disease problems are attracted to drought stressed plants, and plant dieback or death can occur more rapidly during this period.
Most plants in our area need water in the summer and early fall. Proper irrigation is the most common method to correct drought situations. Mulching the drip-zone of trees and plants will help conserve the soil moisture and it will also improve the soil structure. Proper irrigation can be accomplished any time of the day, but it is more efficient to water early in the morning or later in the evening, because evaporation is less. The rate of application should be no more rapid than the rate at which the soil can absorb it. Give your plants the equivalent of 1” of water per week during dry periods. When temperatures rise about 90º you will need to water more. Remember to conserve water where possible, because it is a valuable resource which is becoming more scarce.

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Oregon Garden’s Signature White Oak Gets Needed Surgery

At the age of 400, you’d probably expect to begin to feel some wear and tear. Well, the 400-year-old Oregon White Oak, which is the signature oak at the Oregon Garden, in Silverton is no exception. It has a large branch that was failing and which could split the tree if it fell. Over the Earth Day weekend, the Portland based company, Collier Arbor Care, volunteered to perform some limb surgery which it hopes will send the tree on its way to another 400 years of life.

Arborist John Dale, of Collier Arbor Care examines a trunk bulge on the 400 year old signature white oak tree at the Oregon Garden in Silverton

“These are exceptional trees, and I see no reason why it can’t live another 400 years. After all, it was an adult when Lewis and Clark made their journey here, and it would be a shame to lose that kind of link with the past,” said Terrill Collier, president of Collier Arbor Care, who chairs the Oak Grove Committee that helps manage the garden’s oak grove.

On Friday, April 16, a crew of three Collier arborists began a two-day process of cabling together limbs in the expansive canopy to mechanically reduce the potential of the tree splitting under the onslaught of winds, ice and snow over the next decades.

Collier’s crew installed six cables. The process calls for using a pulley system to temporarily bring limbs closer together to be cabled. Then a threaded rod is put through the branches to be cabled. Eye nuts are screwed onto the threaded rods. A cable is attached to the eye at the end of each threaded rod, the pulley is released and the newly installed cable mechanically holds the limbs in place.

“I know all this sounds a little technical and may be hard to visualize, but it all makes sense when you see how it’s done,” said Collier whose firm has provided pro-bono care for the tree for the last four years. A thorough pruning and shaping of the tree took place three years ago, “and you can imagine what a job that was when you see how big this tree is!” said Collier.

The garden’s signature Oregon White Oak is part of its oak grove, which Collier’s committee hopes to restore to its natural state. Currently it contains blackberry bushes and exotic or non-native plants.

“The Oregon White Oak is one of the few deciduous trees in Oregon which live this long. It’s a really special tree, and I wouldn’t be surprised if there were quite a few others around in this age range,” Collier said.
Collier’s firm also is performing volunteer maintenance on Vancouver’s Old Apple Tree, thought to be the oldest living apple tree in the Pacific Northwest.

(Left)Trunk of a mature Katsura Tree (Top Right) Fall brings a spectacular show of bright yellow foliage with the scent of cotton candy (Bottom) Right) Mature Katsura Tree

From left, Peter Daves and Terrill Collier of Collier Arbor Care, Kim Silva and Keli Yeats of Friends of Trees, and homeowner Jim Cilek, with his dog Cinnamon.

Featured Tree: Katsura (Cercidiphyllum japonicum)

Looking for the perfect tree for the open space in your landscape? Wanting a shade tree with four-season appeal without the massive size of oaks or maples? The Katsura may be the tree you are looking for.

Introduced from China and Japan, the Katsura has a maturity height and width of approximately 40 to 60 feet. The growth habit when young is pyramidal and rounded when matured. The leaves average 2 to 4 inches long and heart shaped. Young leaves emerging in the spring are purplish, fading to a light blue green in the summer. In the fall the Katsura puts on a spectacular show of bright yellow foliage with an aroma said to be that of cotton candy.

The Katsura is multi-stemmed (more than one dominate trunk) or a single trunk with dominate side branches. The bark is shaggy and is very showy during the dormant season. Also available is a gracefully weeping variety.

The Katsura is a low maintenance tree with no serious insect or disease problems. Once established in the landscape the Katsura tree will be admired and appreciated for many years.

Collier Arbor Care Supports Friends of Trees in Hillsdale Effort

On March 13, thirteen Collier Arbor Care employees showed up to assist the Friends of Trees tree planting effort in the Wilson Park areas of HIllsdale. In this joint effort with members of the Friends of Trees, 26 trees were planted in the Hillsdale and Marquam neighborhoods. Since 1989, Friends of Trees has distributed more than 260,000 free trees and shrubs.

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