Plant Insect & Pest Profiles: The Bronze Birch Borer (BBB)

Plant Insect & Pest Profiles: The Bronze Birch Borer (BBB)

Treatment in Spring Can Help Protect Your Birch Trees

The Bronze Birch Borer has become a problem in the Pacific Northwest.

Recently Washington and Oregon have had trees infected with bronze birch borers in white-barked Birch trees. Species such as Betula pendula, Betula Jackmontii, Betula lenta, Betula lutea, Betula papyrifera, and Betula populifolia are at greater risk, but other birch trees are also susceptible to these pests.

How to Identify the Bronze Birch Borer

The Bronze Birch Borer is a beetle, but the larval form is the more destructive creature. The beetle is a bronze or dark green color, with bright, shiny green wings, around ½” long. The female deposits approximately 75 eggs, annually, into cracks and crevices in the tree bark in May or June. The larvae hatch around 10 days later. They are ¾” long, cream-colored with a brown head, with pincers towards the back of the abdomen.

Conditions Birch Trees Prefer and Why they Can Become Susceptible

Birch trees have shallow roots and prefer that they stay moist, tolerating slightly acidic soil. Ideally their roots want some shade, and they dislike sustained hot and dry conditions. They can also be stressed from growing in heavy clay soil, which is common in our area. Birch trees should only be pruned when dormant, as pruning when in leaf can cause the sap to run and they will lose energy and be more susceptible to the Bronze Birch Borer and other diseases.
Pruning in Fall/Winter, when the borers are dormant, will also protect the tree.

Damage to Birch Trees

The larvae eat the tree cambium layer, which is found between the bark and the heartwood. The cambium is the growing, living part of the tree that puts on yearly rings, and also contains the xylem and phloem transportation system. The xylem transports water and phloem moves sugars and nutrients from the roots to shoots, or to wherever is needed in the tree. If this system is disturbed then the top of the tree cannot receive the nutrients and water it needs to survive. The damage is at first, invisible, as it is underneath the bark. Often, the first damage that can be seen from the borer is wilted branches and yellowing leaves at the top of the tree. But the roots can also be damaged and eventually the whole tree can be killed. The larvae and beetles themselves are hard to see.

Bronze Birch Borer Life Cycle

Once the borers hatch in the Spring, they move around the tree under the bark, in feeding tunnels, until the Fall, where they over-Winter. Sometimes ripples can be seen in the bark covering the tunnels. The larvae pupate and return as beetles in the Spring. They emerge from the bark through a ‘D’-shaped hole, where they eat new foliage and then start the cycle all over again, laying their eggs in the bark.

If the tree is infected by Bronze Birch Borers in the Spring, by late summer, the foliage will turn brown, usually starting in branches in the crown of the tree of 3/4” to 1”diameter. The infection will work it’s way down the trunk.

Prevention

  • Keeping trees healthy and vigorous is the best prevention. Make sure they are well watered when it’s hot, and fertilize in the Spring to give them the nutrients they need. Mulch with bark dust over the roots, to keep them cool, but don’t pile mulch up against the base of the tree.
  • Remove dying trees and infected branches, so the borer won’t spread to other trees.
  • When planting new birch trees, choose resistant varieties, such as B. nigra ‘Heritage’ and B. nigra.

Treatment

Insecticidal sprays can be used in May and June, just as the larvae are starting to emerge. Systemic insecticides can also be used as a soil drench, around the root zone of the tree, to target the beetles as they emerge, and the larvae living beneath the bark.

For more information on Bronze Birch Borers OSU and Morton Arboretum both have some great information.

Bad Pruning: What not to do!

Bad Pruning: What not to do!

Use an Expert Tree Service to Maintain Healthy Trees

Driving around Vancouver, and Clark and Cowlitz counties, we see some bad pruning. It makes us sad for the trees and homeowners, as we know that bad pruning can shorten the life of once beautiful trees, removing the many benefits that trees can bring to a property. More than that, once gracefully, branching trees are reduced to ugly stumps, and it can take a long time, and an expert tree service to rehabilitate bad pruning.

 

Bad tree pruning techniques to avoid:

  1. “Topping” You may have heard tree topping discussed, but it’s not a real pruning technique, used by tree professionals. A guideline for good pruning, used by expert tree services, is to maintain the natural growth habit of the tree. The natural flow of tree growth is from the trunk (coarse growth) to branches, ending in twigs (fine growth). It’s important not to cut off branches in the middle, topping the tree, and cutting off its ability to manufacture food for itself, by taking off most of the green leaves. The stubs left are susceptible to decay, and insect invasion. Branches that sprout from the stumps have a weak branch attachment, and are at risk for future failure. It’s very hard to bring a tree back from topping, requiring years of corrective pruning.
  2. “Lionstailing” is an over-thinning of the interior of the tree, resulting in what looks like a ‘Lionstail’ on the end of every major branch. This leads to an uneven distribution of leaves and weight at the end of branches, and long-term can lead to branches breaking, as the wind catches them. These trees are good candidates for severe storm damage. It is very important to retain the ‘inner green’ of trees, as they help to feed the tree. Ideally thinning cuts should be made throughout the tree, not just in the center, and weight should be taken off the ends of branches, if needed. It is recommended that not more than 15-20% of the tree canopy is removed at one time.
  1. “Pollarding” – The technique of pollarding originated in Europe, dating back to ancient Rome, as a way of producing firewood from living trees. It’s also a way of keeping a tree small enough to fit the space it’s planted in. It’s essentially a form of topping, and is still used in some formal gardens and along city streets. The upper branches of a tree (usually a Plane tree – Platanus species) are removed, leaving big, knotted stumps. These increase in size as the tree is pruned back annually. A multitude of thin, whip like branches grow back on these knots in the Spring. These trees are not particularly healthy, since the stumps can encourage weak growth and decay, and the trees are essentially stunted by severely cutting them back. This technique, if used at all, should only be used on younger trees. Pollarding could kill an older tree.
Winter Pruning

Winter Pruning

As we’re looking forward to Spring, and hoping it’s around the corner soon, late winter is a good time to do some pruning, particularly on deciduous trees and shrubs. In Winter we can view the overall structure of a tree or shrub, without it being obscured by leaves. It’s also healthier for the tree to be pruned while dormant, before the sap begins to flow in Spring. Pruning in the summer will take away some of the plant’s energy (in leaves), this is stored safely in the roots in the winter.

Prune trees and shrubs that bloom on new wood

First of all, make sure that you’re not pruning a tree or shrub that will be blooming soon, like Forsythia, or Western Redbud (Cercis Occidentalis) or the Star Magnolia (Magnolia stellata), unless there are some dead or diseased branches that need to come out.  Plan on pruning them after they bloom.  Similarly, don’t prune your Rhododendrons now, or you’ll cut off all those beautiful blooms.

Why Prune

Secondly, be clear on why you’re pruning.  Maybe the tree’s size needs to be controlled, or the branches need thinning, so that lower branches, or plants growing beneath can get more light.  Or perhaps there are some structural defects that need to be addressed; dead or diseased branches to remove, or crossing branches growing in the wrong direction.  Regular pruning will help light penetrate the canopy, and air circulate, resulting in a healthier tree.  Over time you will develop an eye for the pruning cuts that should be made.  But be careful of over pruning, you should prune out no more than a quarter of the canopy or even less, it’s best to be conservative on this.  If you are not sure, consult an Arborist, there is great value in a well pruned tree!

Selecting the correct species to prune in Winter

Trees and shrubs you can prune right now tend to bloom in summer; June and beyond.  Crape Myrtles (Lagerstroemia indica), which are late summer bloomers and trees, such as the Katsura tree(Cercidiphyllum japonicum), Smoke tree (Cotinus species), Hornbeams (Carpinus species) and Oaks (Quercus species).  Shrubs such as Buddleia, Abelia, Caryopteris, and Hibiscus can  be pruned now.  Fruit trees, such as Apples and Pears can also be pruned.  Since they are grown for fruit, the reason for pruning is to access fruit, and to develop a strong leader and well-spaced scaffold branches to bear fruit.

These plants will bloom on this year’s growth, so there’s no danger of pruning off blooms.  Often there are spent blooms to trim back, and pruning will also help to control the size of shrubs and trees, encouraging new growth, and keeping them more compact, and less woody.

Some evergreen trees and shrubs, such as Spruce (Picea), Fir (Abies), Yew (Taxus), Holly (Ilex), and Boxwoods (Buxus) can also be pruned in late winter, while dormant. 

As you’re pruning, always keep in mind the habit (the way the plant wants to  grow naturally), and try to accentuate its features, and allow it space to grow.

Resources

The International Society of Arboriculture (ISA), has a handy guide on tree pruning for the consumer:

https://www.treesaregood.org/treeowner/pruningyourtrees

 

Tree Planting Procedures for Fall

Fall is a great time to install a new landscape and plant trees and shrubs to increase their transplanting success.

Planting while dormant

Ornamental trees begin to go dormant as temperatures cool in the fall. They typically are dormant from the first freeze of the season until the temperatures start to warm in the spring. A general rule of thumb is Thanksgiving to Valentine’s Day. While dormant, the tree is not actively growing, so its need for water and nutrients naturally decreases. Planting while your tree is dormant greatly reduces the risk of transplant shock. Dormant trees can withstand winter conditions but you should still take care in planting them correctly to avoid stress and shock once spring returns.

Diseases and Pests are also dormant in the winter. This significantly reduces the susceptibility to your trees becoming under attack. Certain ornamental trees are best protected when applying dormant oil in the winter. Contact us for more information about keeping your trees safe from pathogens all through the year.

Winter Watering Needs

During winter, your trees’ need for water is greatly reduced compared to what it needs for foliage and flowers in the growing season. Trees do still need water in the winter in order to slowly adjust to their new surroundings and establish their root system. A common mistake is planting trees during a dry spell or prior to freezing temperatures. It’s always a good idea to water your new trees in at the time they are planted. Rain offers inconsistent moisture and new roots need consistency to start to establish roots. When the ground freezes, plants cannot take up water and so it’s important they had it available prior to a major drop in temperatures.

Planting depth and planting on a slope

The correct soil depth is always important when planting trees. Established trees can help protect your landscape from erosion, but if trees are planting on a steep slope in the winter, they can pose a landslide hazard. One technique is to build a terraced garden. The stonework will correct the slope issues and then your trees can be planted normally. As their root systems grow, they will strengthen the hill’s stability without the slope as a direct force against them.

You also need to take care to avoid planting the base of your tree too deep or too shallow. Soil should cover the entire root mass at the tree’s base and should not bury the trunk. A good rule of thumb is to emulate the depth of soil your tree had when planted in its pot.

Planting too high can expose roots, causing your new tree to dry out. Planting too low can submerge the base of your tree in soil or water, causing its roots to rot.

Planting in the right location the first time

Finding the right site for your tree is really important. Frequently transplanting can cause stress and make your tree more susceptible to problems later. Some things to look for when choosing the site for your tree:
Consider its mature height and the potential to obscure your view. Do not plant too close to your fences, home, or garage. Consider the direction of the wind and plant your trees out of the wind’s path to prevent problems later. If there are light winds, staking during the winter can help a new tree from blowing over, but avoiding this issue in the long run is recommended by planting in the right spot the first time.
In the Northwest it’s safe to plant trees almost year round (as long as the ground is not frozen),

For your planting needs contact Frontier Landscaping Inc.

Frontier Tree Care provides emergency tree services if the need arises. Save our number this winter in case you have a tree emergency

Fantastic Japanese Maples for Fall Color

Fall in the Northwest is a time we always look forward to. Along with cooler days it’s also the time when trees give us a beautiful array of fall colors. Japanese Maples have steadily gained popularity in Northwest gardens for several decades. Japanese Maples are desired for their versatility in the landscape and exceptional fall color. There are so many varieties available on the market, you can easily source the right one for any sized garden: urban gardens, suburban landscapes and larger properties.

Their vibrant fall color makes them a favorite as a focal point in landscapes. They prefer slightly acidic sandy loam soils. Even in the winter months, they have a structure that adds elegance to your landscape. They tolerate our naturally acidic soils and wet winters and are equally beautiful in a mixed landscape border or as an accent plant. Here are a few of the best varieties for Northwest Gardens, hardy in USDA zones 5-9. 

Green Lace-leaf Japanese MapleAcer palmatum ‘Seriyu’ 

Green Lace-leaf Japanese Maple 

‘Seriyu’ means Blue-Green Dragon in Japanese. This variety gives all the delicate texture of weeping Japanese maples but with an upright growth habit. Soft green dissected palmate leaves are numerous on very elegant long branches. The mature habit can be grown with a central leader or as a multi stemmed tree. The fall color transforms the tree into a multitude of warm red and orange shades. ‘Seriyu’ is a good specimen for containers or near a water feature. Mature height 15-20 feet tall.

Coral Bark Japanese MapleAcer palmatum ‘Sango kaku’ 

Coral Bark Japanese Maple 

If you’ve been looking for a specimen tree or large multi-stemmed shrub with year-round interest, you’ve found it in Acer palmatum ‘Sango kaku’ also known as Coral Bark Maple. These small trees have the delicate palmate leaves and outstanding fall color typical of Japanese Maples. ‘Sango kaku’ is even more impressive with new growth emerging a bright red that becomes even more vibrant in the winter. You can plant these as a landscaping focal point or a container tree, in part shade to sun. Coral bark maples are at their best when protected from the hottest sun of the day and high winds.

Maintain with annual pruning to stay below 15 feet, eventually maturing at 20-25 feet tall.

Emperor 1 Red Japanese MaplesAcer palmatum ‘Wolff Emperor 1’ 

Emperor 1 Red Japanese Maples

This variety is known to be one of the toughest of the upright growing Japanese Maples. Leaves emerge in spring to a brilliant crimson red and maintain their dramatic color throughout the Summer. When Fall color begins the foliage transforms to a vibrant bright red before Winter. Even in dormancy the vase shape structure of ‘Emperor 1’ makes it an outstanding tree in any sized landscape. They can tolerate afternoon sun consistently better than other varieties. They reach about 25-35 feet tall and wide.

Weeping Red Japanese MapleAcer palmatum ‘Crimson Queen’

Weeping Red Japanese Maple 

Acer palmatum ‘Crimson Queen’ is a weeping variety of Japanese Maple. This very popular landscape tree is known for its finely textured palmate dissected leaves and incredible red fall color. These typically mature at 6-8 feet tall and wide. Their mature height is based on where they are grafted. With training they can reach heights of over ten feet. Plant in full sun to part shade, and maintain regular intervals of summer irrigation to keep their leaves soft texture. They need protection from high winds.

This variety can handle the hot sun and drier months better than other Japanese Maple varieties, but it’s still best to maintain summer irrigation consistently for all Japanese maples. Deep and regular watering as your tree gets established is the key to avoiding crispy leaves and maintaining the plant’s overall health.

Orangeola Laceleaf Japanese MapleAcer palmatum dissectum ‘Orangeola’

Orangeola Laceleaf Japanese Maple

Orangeola Japanese Maple is a stunning landscape tree whose foliage goes through various changes throughout the seasons. In the fall, ‘Orangeola’ continues its color changes and develops bright flaming red and burnt orange colors for a powerful display.

Unlike other weeping Japanese Maples – whose growth pattern is to spread wider than they grow tall – the Orangeola Japanese Maple has a relatively modest spread of 3-7 feet. It can grow up to 8 feet tall. It is, therefore, more suitable for planting in containers than other lace-leaf maples, and it’s a beautiful specimen on porches or patios.

In fall, ‘Orangeola’ continues its color changes and develops bright flaming red and burnt orange colors for a powerful display. If grown in a location with more exposure to bright light Japanese Maples can have more intense coloring.

Japanese maples will reward you for decades with beautiful shape, form, and fall color! 

Contact Frontier Tree Care for your technical pruning needs this fall and winter. We can assess your trees for corrective maintenance, pruning crossing branches and removing any dead wood ahead of winter storms. With regular tree care and landscape maintenance your Japanese maples will be staples in your Northwest garden.

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