The Case of the Fruitless Plum Tree

I wanted to share a short story about a plum tree.
I’ve been working on a plum tree for a client for the past 3 years. They originally got in touch because their 8 year old plum had only been producing one or two plums a year, and was otherwise looking healthy and growing vigorously.

The healthy and vigorous plum tree in question

The healthy and vigorous plum tree in question

I thought maybe it could be a pollination issue, despite the tag saying it is “self fertile”, which in my experience is true for Italian prune plums. I was a bit suspicious though when I took a good look at the leaves. They appeared to be a little bit of a different shape and a bit glossier than the typical Italian plums I see. I was also curious that it said it was a semi dwarf, which means it had been grafted onto a dwarfing rootstock.
 

Semi Dwarf Italian Plum, says the tag...

Semi Dwarf Italian Plum, says the tag…


 
I suggested either planting another plum tree to help with pollination, or grafting some additional varieties onto the tree. There wasn’t a lot of additional space in the client’s yard for another tree, so I ended up putting 4 grafts (new varieties of plums) onto the tree in spring 2019.
I was called back for a spring pruning this year (2020) and was greeted by a tree that had put on a ton of new growth, and had several plums! The most interesting thing to me was that the side of the tree where two of my grafts took (and flowered) the original tree had 4 immature plums on an adjacent branch! The proximity of the branch with the plums, to my grafts, gives me confidence in saying that the issue all along was a pollination one, and that whatever scion (grafted variety) they grafted to whatever rootstock, had some unintended consequence of making the tree self-infertile. The tag was wrong. I wonder how many other people are out there with a fruitless plum tree…
 I pruned the tree to allow the new grafted branches lots of light and space. Hopefully they will become significant branches in the next few years and the tree will bear an abundant crop of Italian prune, Golden Drop, and Mirabelle plums.
 

If you’re interested in getting additional varieties of fruit on your trees, get in touch and we can schedule an appointment for the spring.
 
Check out an older post of mine for more information on grafting

A fruiting graft

A fruiting graft

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Decay as Habitat

I knew chickadees nest in trunk cavities, but I didn’t realize they would take advantage of something this small and so close to a house. I spotted this black-capped chickadee nest in a partially decayed lilac branch.
 
Dead and decaying branches support wildlife! So if it’s not endangering you or your property consider leaving that dead branch or tree part where it is. It’s also possible to create nest boxes and other habitat features in sections of trunk that can be left standing when a tree removal is necessary. See link below.
 
Excuse the poor quality photos. It’s hard to take a good photo of a cavity nest that does not want to be found! Four small white eggs can just been seen in the center of the 2nd photo. The last photo is a severely rotten rhododendron trunk that was home to a chestnut-backed chickadee family at a different site. The nest was so far down the decayed stem, I couldn’t even see it, but I did see several baby birds fly out when I was working in the area (I stopped working in that area once I discovered the nest).
 
Check out the work of Brian French who has been bringing wildlife habitat preservation and creation to the forefront of the Arboriculutre industry recently: http://www.arboriculture.international/environmental-1#environmental
 
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Callus Growth

Apple Callus Growth
An example of how allowing new shoots to grow at the margins of a pruning cut help it heal over quicker. Ideally large cuts like this would never have to be made, but sometimes we don’t get around to pruning when we should. You can see the side that has the new shoots is healing over much quicker than the other side without any growth. This is on a large apple tree. After a few years the shoots are usually thinned to one or two of the strongest.

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Strawberry Tree Pruning

This Arbutus unedo, or Strawberry Tree, had been hedged years ago. The client wanted it to look more like a tree. Hedging creates lots of new growth points in the upper canopy, and generally trees have fewer growth points. By leaving the leaders that were well attached and growing in the directions I wanted, while removing leaders in crowded areas of the canopy, I was able to get a good start on making it more tree like. I started by removing a few lower larger diameter branches that seemed especially crowded, then focused on thinning the areas in the upper canopy that were topped in the past.

Before pruning

Before pruning

After pruning the Strawberry Tree (Arbutus unedo)

After pruning the Strawberry Tree (Arbutus unedo)

Posted in Before & After (photos) | 1 Comment

Monkey Puzzle Tree

Did you know the seeds from monkey puzzle trees are edible? Latin name Araucaria araucana.
I’ve been out collecting the fallen seeds around my neighborhood in Seattle a few times recently. Boiled for 5 to 10 minutes, and then cut open, they taste similar to a roasted chestnut.
They are native to a small area in the Andes of central Chile and over the border into Western Argentina. The trees are usually diocecious, meaning there are separate male and female trees. So if you see a tree with no seeds, it may be a male, or perhaps a female that is not within pollination range of other trees.
 

A typical and healthy Monkey Puzzle tree (Araucaria araucana) in Seattle.

A typical and healthy Monkey Puzzle tree (Araucaria araucana) in Seattle.


The spiky leaves would "puzzle a monkey" as to how to climb the tree.

The spiky leaves would “puzzle a monkey” as to how to climb the tree.


Individual seeds from the Araucaria.

Individual seeds from the Araucaria.

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Silver Spotted Tiger Moth

In early May I noticed some caterpillars in a Douglas Fir I was pruning away from a roof in Seattle. A little investigating online and in a few of my resource books confirmed that they were silver spotted tiger moth caterpillars. Douglas fir (Pseudotsuga menziesii) is the principal host, but they also feed on a few other conifer species. One of the keys in identification of this species is the large size of the caterpillars at this time of the year (mid April to early May). Nearly all other species don’t reach this size until later in the summer, so seeing a caterpillar of this size narrows down the options tremendously.
Their eggs hatch in the late summer or fall, and they will feed on needles during warmer winter days. By June, Lophocampa argentata start spinning cocoons near their host tree. Adults start flying in July and August, laying eggs to start the life-cycle again.

Thankfully natural predators such as parasitoid wasps and songbirds nearly always keep this defoliator in check and don’t allow it to cause long-term damage. If their presence becomes intolerable, the individual branches with the webbing can be pruned out and destroyed.

Resources:
http://pnwmg.org/pdf/silverspottedtigermoth.pdf
https://pnwhandbooks.org/node/6865/print

Lophocampa argentata on a Douglas Fir branch

Lophocampa argentata on a Douglas Fir branch

Notice the caterpillar frass caught in their "tent"

Notice the caterpillar frass caught in their “tent”

Posted in Pests and Diseases | 1 Comment

Cherry pruning

I wanted to share a couple photos of a cherry I pruned last week. I started a multi-year process to create more healthy fruiting branches lower in the canopy where fruit can be reached. This first pruning in many years started by removing some of the highest more vertically-oriented branches in the upper canopy to create more light and airflow lower in the canopy. Thick areas were also thinned so the branches can dry out sooner after rains, which will help reduce fungal infections. Many people say a sign of good pruning is that it’s not entirely obvious that pruning has occurred. If I may so myself, I think this is a good example. There’s an obvious difference between the before and after, but if one just saw the post pruning photo, it’s not obvious it’s been pruned.

Lots of thick areas in the canopy, and several vertical shoots going nowhere but up.

Lots of thick areas in the canopy, and several vertical shoots going nowhere but up.


After thinning some of the thickest areas and reducing the height appropriately.

After thinning some of the thickest areas and reducing the height appropriately.

Posted in Before & After (photos), Fruit Trees, Tree Care | Leave a comment

Planting Trees

When planting trees it’s important to remove all the soil that it comes with. Besides making sure you’re planting it at the correct depth (very important!) which is very hard to tell without removing the soil, you’re helping the tree get accustomed to its new home quicker. Often the soil it is grown in at the nursery is heavily amended to make the trees grow quicker. If this is left on the root ball of the tree when you plant it, and your soil is not as appealing to the tree, its roots may just hang out in this little zone for years without much exploratory growth outwards to create a strong and stable root system. It’s also important to look for and remove any girdling or circling roots and trim off broken or damaged ends. Poor planting often doesn’t show up for years, and may not become a problem until there’s a particularly strong windstorm, or a very dry summer, and those circling roots can’t hold the tree up or find sufficient water.
I removed a number of dead Arborvitae shrubs last month in North Seattle that died in the summer 2017 drought. It was very obvious that the only preparation to the tree was the burlap taken off their roots, and they were then just dropped into a hole. You can see the slick edge of the root ball from one of the dead arborvitae in the photo below, hardly any roots grew out of this packed soil into the native soil it was planted it.

The slick edge of the rootball is still visible 3 years after transplanting. New roots had trouble growing through this into the native soil, eventually leading to its demise, as it couldn't get enough water during a drought.

The slick edge of the rootball is still visible 3 years after transplanting. New roots had trouble growing through this into the native soil, eventually leading to its demise, as it couldn’t get enough water during a drought.

Carefully washed roots of a Japanese maple, ready to be planted

Carefully washed roots from a Japanese maple, ready to be planted

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Kretzschmaria deusta

It may sound like some kind of monster, and in some ways it is, though normally it just appears as in innocuous fungus at the base of hardwood trees. It’s a fungus called Kretzschmaria deusta found in temperate climates worldwide that can cause fairly severe decay. It has two visual forms. In the spring it grows new fruiting bodies that are gray with white edges that emerge directly at the base of trees and logs that are infected. Later in the year these turn into black crusty lumps that look like charcoal blisters. Both forms can be seen on a Big Leaf Maple in the photos below that I took during the spring in South Seattle.

Both forms can be seen in this photo. The new gray and white growths, and prior years black coal looking lumps.

Both forms can be seen in this photo. The new gray and white growths, and prior years black coal looking lumps.

The fungus is a decayer of both cellulose (the fibers that add flexibility) and lignin (which give rigidity to wood). Thus it can be a fairly damaging fungus.

A glove for size comparison. K. deusta can be damaging to trees, usually indicating some significant decay. Any sightings should noted and investigated further.

A glove for size comparison. K. deusta can be damaging to trees, usually indicating some significant decay. Any sightings should noted and investigated further.

Posted in Fungi, Tree Care | 1 Comment

Prune in Moderation

Another reason not to prune a lot out of a tree all at once- I was working in Seattle in the upper canopy of a narrow leafed Ash (Fraxinus angustifolia) last week, and noticed the top of a number of the major limbs were no longer alive. It appeared that a huge amount of foliage had been removed by the power company a couple of years prior, exposing once shaded limbs to full sun all day long. The tops of these limbs got sunburned and died. They are now more susceptible to insect pests and diseases, potentially weakening the tree. The lesson: prune in moderation whenever possible!
As a general rule no more than 25% to 30% of the total leaf area (when leafed out) should be removed during any one year period.

Sunscald on an Ash branch from sudden exposure to day-long sun.

Sunscald on an Ash branch from sudden exposure to day-long sun.

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