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Trees

Bronze birch borer related pruning

By | Arborist Insights, Trees | No Comments

Because I am ISA certified, tree-related tasks are automatically given to me by default. And that’s fine. This blog post is about a birch tree which exhibited top dieback. So I was sent in with pole pruners and an extendable Stihl chainsaw to take care of the request.

 

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It’s not super clear but the top leader is dead.

 

Once I took out all of the dead branches, I pruned the live parts of the tree to give it some sort of shape. Then I hauled out the debris up to the road for later truck pick up. Only later did I realize that my boss expected me to take the whole tree down! Not my style anyway.

Since we suspected the cause of the dieback to be the bronze birch borer (Agrilus anxius) my approach was correct. Pruning out affected limbs is the way to do it. I just couldn’t burn the diseased branches on a strata site surrounded by woods. My only hope is that no adults emerged before the debris was processed with other green waste.

Bronze birch borer

Adult bronze birch borers are half an inch long and have slender dark green bodies with metallic bronze sheen. In summer, females lay their eggs in bark crevices of weak and stressed birches. They prefer sunny, south facing branches.

Larvae hatch 14 days later, enter the bark and feed on sapwood. After one or two years adults emerge by chewing D-shaped holes in the bark.

Signs

So let’s review. Bronze birch borers cause treetop dieback, leaf wilting on branches and D-shaped exit holes in the bark

What can we do?

Since the bronze birch borer only picks on weak and stressed birches we should keep our birches in good shape with regular watering, feeding and pruning. Also, put your birches in shadier corners.

One other idea is to plant birch borer resistant river birch (Betula nigra) cultivars.

If you are lucky, you will get some help from natural allies like parasitic non-stinging wasps and woodpeckers.

The birch featured in this blog post is still alive and standing.

 

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After removing all dead branches and pruning others to give the tree some sort of natural shape.

 

Source: GardenMaking magazine no.30, pp.56 and 58.

Still purchasing lady beetles for your garden?

By | gardening, landscape maintenance, Trees | No Comments

A few years ago I met a home owner at one of our sites and she told me about her annual lady beetle buy and release events. I smiled politely and privately thought she was insane and had way too much disposable income. She paid $16.95 retail plus tax for a bag of lady beetles. As we learn from the fact sheet below this biocontrol business is extremely lucrative.

 

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Now, a few seasons later,  there is a new Fact Sheet from the University of Washington Extension that clarifies the issue and it happens to be co-authored by my favourite horticulture scientist Dr. Linda Chalker-Scott.

As it turns out many gardeners buy lady beetles for their gardens and landscapes. And the fact sheet concludes that “release to open gardens and landscapes is unlikely to be successful.” Now my burning question is answered.

Control

Adult and larval beetles control aphids and scale insects, mites, beetle larvae and immature bugs.

 

Aphid problem

The site mentioned above has lots of tulip trees (Liriodendron tulipifera) which are known to attract aphids. The aphids suck on the new leaves but otherwise don’t harm the trees. Incidentally, don’t miss tulip tree flowers. They are spectacular.

Since aphids can’t process sugars, they excrete them. That’s why honeydew drops on leaves, cars and sidewalks. Then lady beetle sales go up. The lady swore that her lady beetle releases are effective. OK.

But perhaps you don’t have to spend your after-tax dollars on lady beetles. What if you can attract them naturally? Grasses and wildflowers will attract them to your gardens. Lawns not so much.

As we learn from the fact sheet, lady beetles eat fungus, fruit and occasionally vegetation. Adults look for sugar sources such as nectar or honeydew. These energy-rich supplemental foods improve lady beetle reproduction and survival over winter.

Take it easy on insecticides because they kill the target pests and natural predators.

Good or bad idea?

There are some negative aspects to this whole biocontrol business. First, we are removing populations from their natural ecosystems which may not be a good idea.

Second, native beneficial insects may suffer when we introduce non-natives. And third, introducing lady beetles may transport parasites.

Conclusion

In conclusion, I must say that the lady gets a gold star for spending $16.95 plus tax on a bag of lady beetles; and for inspiring this blog post. As we know from the new fact sheet, these lady beetle releases are unlikely to be effective. And yet, she swears by them. Perhaps the tulip tree honeydew attracts the lady beetles naturally.

I say, try to attract lady beetles naturally and save your money. Perhaps you can donate some cash to the University of Washington Extension so they can produce more science-based fact sheets.

Chinese windmill palms on the West Coast

By | Arborist Insights, Species, Trees | No Comments

I love palms! They remind me of tropical locations we all love to visit. So when the August 2017 issue of Arborist News featured an article on palms, I finished it on the same day. It also gave me one credit towards my recertification.

This blog post features a palm we see in the Vancouver area. I learned about Chinese windmill palms (Trachycarpus fortunei) after they got absolutely hammered this past winter at a client’s place. The lady was clearly distressed because the fronds were all beat up and brown. Plus, her palm was situated near her pool and outdoor kitchen. So I did the only thing I could; I pruned off the brown fronds. When my client retreated into her beautiful home, I snapped a photo of the palm tag and made a reminder to myself to check the species online.

 

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This poor palm didn’t make it. All growth originates from the top and clearly, not much is happening there. But perhaps there is hope. See the next picture.

 

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We almost gave up on this palm but look at it now!

 

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This specimen survived the winter nicely.

 

Winter hardiness

Trachycarpus fortunei is the most tolerant to cold temperatures of all palmate palms. But remember, our last winter in British Columbia was the harshest winter in thirty years. My boss almost lost his juvenile Chinese windmill palm this year. See the second picture above. And it just so happens that my boss and my client both live in an area which held on to snow the longest.

The other complication is that mature Chinese windmill palms handle cold better. Younger specimens are most susceptible.

Details

The Chinese windmill palm is a solitary fan palm with a slender trunk. The key distinguishing feature of this palm is a messy layer of brown fibers that turn gray with age.

 

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Note the messy fibers.

 

The palmate fronds are up to two feet (0.6m) wide and deeply divided into one inch (2.54cm) wide, stiff segments. The petiole is 1.5 feet (0.5m) long and armed along the base with blunt teeth. Yes, the teeth are blunt but weeding around this palm is still unpleasant.

Mature specimens can reach 25 feet (7.6m) in height. This species is a good selection for small gardens.

 

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All brown fronds should be pruned off.

 

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This is a picture after pruning.

 

What palms grow in your home area?

 

References: Arborist News August 2017 volume 26, number 4, pp. 12-21. This is an excellent article. If you are ISA certified you can earn 1 CEU credit.

On branch attachment

By | Trees | No Comments

One day last year I went out for a jog at Shoreline park in Port Moody, British Columbia and ran past a fallen tree. Ok, trees fall all the time in the forest. But luckily the municipal workers made a nice clearance cut exposing one of the branch attachments. See the picture below.

 

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Look how strong this branch attachment is. It belongs there.

 

Strong attachment

What do you notice? Do you see how the branch on the right is firmly attached? It’s solidly in place because it belongs there. It’s a true branch developed in a socket of overlapping wood tissue. So I stopped running and snapped a few photos. Then, after I resumed running I thought about my arborist friend’s tree lecture.

Paul Buikema is one of my tree mentors and his lectures are to be recommended. He related one story, complete with slides, showing a gorgeous deciduous tree with large leaves. I totally forgot the exact species. Paul was asked to prune it so he climbed inside. Then, horrified, he realized that all of the branches he was stepping on were pseudo-branches.

Weak attachment

The tree had been topped in the past and the branches Paul was standing on pushed out from apical meristems. Basically, when you top a tree, the buds nearest to the top push out and develop into branches. These are pseudo-branches, not real, strongly attached branches. They are attached only in the outermost layers of the parent branches and prone to failure.

Of course, Paul didn’t push his luck and bailed out of the project. It just wasn’t safe for him to stay there.

 

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This is an illegally cut pin oak (Quercus palustris). Note the three shoots. They will never be as strong as normal branches.

 

This is an extreme example but it illustrates my point. This pin oak (Quercus palustris) was cut down illegally. Now look at the shoots. They will never be as strong as normal branches. Of course, I love the resilience of this oak. It’s pushing back after getting abused.

 

 

Don’t top trees

So here again we have one of the main reasons to not top trees. As the new pseudo-branches develop into big branches they can snap in wind or ice storms. This is one of the arguments arborists use to talk residents out of tree topping. Insisting on tree topping means that they accept future failure liability. That might scare them off.

If you want to read more about tree topping click here.

 

Help your trees with watering bags

By | Arborist Insights, Reviews, Trees | No Comments

It’s very hot in our July British Columbia landscapes and plants need help. Trees are plants so let’s help them with some supplemental water. One great invention is the Gator watering bag.

 

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A Gator watering bag in action. They work best when they are filled with water. Full marks to this dedicated home owner.

 

 

Installation and benefits

You don’t need any tools to install the bag. Just put the bag around your tree and zip it up. Then add water. The slit is located under the label tag. Once, when I was working for the City of Coquitlam, an elderly couple walked by and wondered how we get water into the bags. Just lift the tag.

The Gator website states that new plantings require a refill every 5-7 days. The average watering time is 5-9 hours. And the benefits? No run-off and limited evaporation.

You can use the bags to protect young trees which should limit losses and labour costs associated with tree planting. That said, some young trees still don’t survive. Perhaps they weren’t planted properly or came from inferior nursery stock.

Not so fast

It would be great if this was the end of the story. Bags go around the tree trunk and deliver much needed water boost to thirsty trees. Not so fast. Just last week I visited my favourite blog called the garden professors. It’s a special blog because people try to use good science to answer questions.

One post that appeared on the blog site was about Gator bags. The author noticed two problems:

a) Many watering bags were empty!? Since the bags were designed to deliver water to trees they should be filled with water. Obviously.

b) A bigger problem was unzipping the bags and discovering bark rot. As the full bags press against the tree trunk they create moist and dark environment and, over time, this can lead to bark rot. Rotting bark then invites diseases and pests.

So I did my own survey on a large site we maintain. I found one tree with a moist bark section; some had bugs hiding under the zipper.

 

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All clear. The bark was dry and, alas, so was the bag.

 

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Same as above.

 

Think of the Gator watering bags as a temporary solution. Install them, fill them up and check on the condition of the bark periodically by unzipping the bag. I hope your trees get through the summer heat without injury.

Katsura tree with too many leaves

By | Arborist Insights, Pruning, Trees | No Comments

“Every year this tree makes too many leaves.” That is a direct quote from the strata owner whose patio looked out on a nice Katsura tree specimen (Cercidiphyllum japonicum). I almost laughed. The tree makes too many leaves every year? Really? I talked to her politely and agreed that some thinning cuts were in order. But too many leaves? That deserved a blog post.

Thinning cuts

On a multi-stemmed tree like this one, thinning cuts are totally fine. Just pick a branch that rubs or crosses with others and remove it. You should be able to create some openings in the crown while still preserving a natural tree look. I didn’t have any trouble with this. It was easy to see crowded spots.

Just remember not to go too crazy. You can always come back next year. I made a few cuts on every tree and assessed it before taking more. And I will assess it again once the trees leaf out.

Too many leaves

This is a joke. Trees know what to do. We can’t tell them how many leaves to produce. What’s the big deal with leaves?

Trees use leaves as factories to make food from sunlight through photosynthesis. This is a free service which produces oxygen for us and removes carbon dioxide from the air. This process also releases water which affects local climate. Without leaves the tree can’t survive.

Once the food is made it is distributed throughout the tree. Upper branches can act as storage sites which is why pruning during drought can starve a tree. Under drought conditions, leaf openings called stomata close to prevent moisture loss. This, in turn, means that carbon dioxide can’t enter therefore food production stops. Then, here comes a landscaper with strata orders to prune trees. As he removes some of the upper branches, he removes food that was stored in them. Boom. Starvation ensues.

Leaves also serve as food for various animals and they act as cover for birds. For example, caterpillars munch on young leaves and are in turn eaten by birds.

Leaves also look great in the fall as they turn color. This katsura tree is no exception.

Too many leaves? Not likely. Let the tree do its thing.

 

Tree planting with West Coast landscape professional Vas

By | Arborist Insights, Trees | No Comments

I love planting trees and shrubs. The world can always use more trees and shrubs. But don’t dismiss tree planting as easy. It has to be done right. The International Society of Arboriculture (ISA) sells a book called “The science of tree planting.” Case closed.

Our mission today was to plant trees on a wild bank to provide residents with a screen. As the trees mature they should obscure the power station visible in the distance.

We planted two tree species (Acer rubrum and Thuja plicata) and one shrub (Pieris japonica.)

 

Step 1 At the nursery

Always be nice to the workers at the nursery. You don’t want them loading your precious plants like pigs. My job was to count the plants and anchor them in the back of the truck. The key is to always handle your trees by the root ball not by the stem. Taking liberties with the stems could damage the tree.

 

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I love tree nurseries! You can improve your plant ID skills and off-road in company trucks. Handle your trees with care.

 

Step 2 Digging

We predetermined our hole locations the day before. The digging was awful because of the wildness of the bank. The bank  was covered with woody debris, ivy and bramble. For this reason I used a tarp for “parking” soil from the hole. I used a shovel to measure the size of the root ball. I also had to adjust for the string and burlap wrapped around the stem. The root flare is actually lower than where the string and burlap meet.

 

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Thuja plicata with wire cage, string and burlap. Watch your back, this required heavy lifting.

 

Step 3 Placing the tree

Once the hole was ready, we carefully placed the tree in the hole. Remember to handle the trees by the root ball NOT by the stem. Once the placement is correct, it’s time to anchor the tree by backfilling the hole to about half way. Another key is to backfill your planting holes with the same material you dug up and placed on your tarp. Some people are tempted to backfill their holes with beautiful new soil but it doesn’t work. Water finds it much easier to enter your planting hole than the surrounding soil and your hole will become waterlogged. This will turn your new tree into a joystick and it will crash down eventually. Use the original material from your digging.

 

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Cut off string and burlap to the top of the cage. Bend wire edges back or cut them out.

 

 

Step 4 Removing string, burlap and wire

Once our tree was anchored in the hole, we cut and removed the string. The top of the wire cage is either cut away or bent back into the hole. The top third of the burlap is also removed. Use scissors or a knife.

Now you’re ready to complete backfilling your hole. Always make sure soil doesn’t go over the root flare. The root flare should be visible. Mounding soil over your stem leads to problems.

Cut all strings on the Thuja plicata stems to free the branches.

 

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Partially backfilled for anchoring; note removed burlap and string, wire bent back and tree root flare located.

 

Step 5 Final touches

Remove all flagging and name tags. Top dress with aged mulch or soil amender. Also take pictures for your files. Monitor your trees just in case if staking is required. The Acer rubrums are tall and if they move, they will get staked. Just remember to remove the stakes after one season. Leaving them on longer prevents the tree from forming reaction wood.

With April rains expected to continue, no watering was required but it is a consideration if you’re planting during a warm, sunny spell.

Pick up any garbage and do a courtesy blow of your work area.

 

 

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All done! Note power station in the background.

 

 

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Two Acer rubrum trees. Note top-dressed tree wells. No staking required but landscape maintenance crews will monitor.

 

I’m curious to see how many seasons it will take for the trees to obliterate the view of the power station.