PCC Spring Tree Care Bracing Practice

Our Spring Tree Care class ventured outside to take care of a Juniperus scopulorum 'Tolleson's Green Weeping'. This was a tree we looked at last quarter in the Winter Plant ID course. The first step is to form a plan.

More than a simple case of included bark, this tree actually had two branches that have grown right against each other. We decided on two bracing rods, one above and one below the crotch.
Once we had our plan of attack we drilled the first hole with a very long 3/8" bit to accept a 3/8" rod.
Juan Carlos hacked the rod down to size.
We decided after quite a discussion to remove one small branch that was crossing and twining around the low branch shown on the left. Then we repeated the process for the upper rod, which was a little trickier to line up, but went fine. To me the tree still looks out of balance and would do better without that lower left limb all together.
Here is a look at our handiwork.
Once we were done, we took a look at some cabling done on the Medlar (Mespilus germanica). It looks very in flower.

Tree Problem 10: Huge Oak

Site: Street tree on S side of my street. (NE Portland)

Biases:

+ Truly impressive tree providing an enormous amount of shade.

- Some of the large pruned branches look a little awkward with long residual stumps.

Tree Characteristics

A truly enormous Oak (Quecus rubra(?)) an over-mature tree with a single trunk DBH 60"! Live crown ratio is around 50%.

Tree Health

New foliage seems vigorous. Certainly puts out enough nuts to keep the squirrels busy.

Site Conditions

Street tree with good southern exposure. Level ground, no direct irrigation except in adjacent lawn.

Targets

Houses, cars, power lines.

Tree Defects

Constrained root space by sidewalk (some lifting) and street (roots spilling over curb)Some exposed roots near base.

Hazard Rating

Part most likely to fail: Branch failure. Low failure potential on Huge parts with significant targets for a hazard rating of 1+4+4 = 9.

Hazard Abatement

Corrective pruning: Prune for branch end weight. Inspect for any potential problems. Rationale: This is such an amazing tree that it is definitely worth aggressive preventative maintenance to head off any problems. The geometry of the tree and mass of the branches does not look favorable for cabling.

Other Recommendations

Climb this tree!

Tree Problem 9: Rotten Maple

Site: Street tree on S side of my street. (NE Portland)

Biases:

+ Big tree providing much appreciated shade late in the day in the summer.

- Has enough decay that you can see daylight through the trunk!

Tree Characteristics

This is some sort of Maple, maybe another Norway (Acer sp.) a young-mature tree with a single trunk DBH 28". Live crown ratio is around 50%.

Tree Health

New foliage looks healthy. Many pockets of decay. Two of the old pruning cuts have decayed together so you could pass something into one whole and out the other!

Site Conditions

Street tree with good southern exposure. Level ground, no direct irrigation except in adjacent lawn.

Targets

House, cars, power lines.

Tree Defects

Rotted out core in several places. Constrained root space by sidewalk. Some sidewalk lifting.

Hazard Rating

Part most likely to fail: branch failure. Severe failure potential on large parts with significant targets for a hazard rating of 4+3+4 = 11.

Hazard Abatement

Get inspected (I think this has happened, in fact). Rationale: Some trees can continue to grow even when the core of the trunk has rotted out, need to figure out if this is such a case or not.

Other Recommendations

If it has enough strength to continue to grow the key is to ensure that growth exceeds the rate of decay. Pruning for branch weight would be a good idea.

Tree Problem 8: Sweet Gum with double leader

Site: Street tree on S side of my street. (NE Portland)

Biases:

+ Tall tree providing much appreciated summer shade.

- The fruit are a pain for roller skating or skate boarding.

Tree Characteristics

A female Sweet Gum (Liquidambar styraciflua) a young-mature tree with a single trunk DBH 27". Live crown ratio is around 40%.

Tree Health

New foliage looks healthy. No significant signs of decay.

Site Conditions

Street tree with good southern exposure. Level ground, no direct irrigation except in adjacent lawn.

Targets

House, cars, power lines.

Tree Defects

Co-dominant leaders from the lowest scaffold branch, possibility of included bark (needs closer inspection). Some exposed roots and sidewalk lifting.

Hazard Rating

Part most likely to fail: branch failure. Moderate failure potential on moderate parts with significant targets for a hazard rating of 2+2+3 = 7.

Hazard Abatement

Inspect for included bark. Prune to subordinate one leader and reduce end weight. Might be a good candidate for cabling to reduce the risk of slitting. Rationale: If this tree fails it could well split in half. Cabling might be a good idea since the leaders are so nearly equal in size, it might be difficult to get one subordinated to the other and it would unbalance the tree to remove a leader.

Other Recommendations

Keep an eye on this one since the risks will only increase with time.

Tree Problem 7: Chestnut under power line.

Site: Street tree on S side of my street. (NE Portland)

Biases:

+ Provides nice shade, and chestnuts which are in principle edible. Contributes some variety to the street tree pallet.

- Looks pretty funky with all the "pruning" to clear the power lines.

Tree Characteristics

A large Chestnut (Casanea sp.) a mature tree with a single trunk DBH 20". Live crown ratio is around 50%.

Tree Health

New foliage looks healthy. Some large dead branches. Many points of multiple attachments presumably from earlier heading cuts.

Site Conditions

Street tree with good southern exposure. Level ground, no direct irrigation except in adjacent lawn.

Targets

House, cars, power lines.

Tree Defects

Very messed up crown. No dominant leader. Bushy growth from earlier heading cuts.

Hazard Rating

Part most likely to fail: branch failure. Severe failure potential on moderate parts with moderate targets for a hazard rating of 3+2+3 = 8.

Hazard Abatement

Corrective pruning. Rationale: Branches with week attachments should be removed or pruned to manage end weight. Branches which are growing around rather than into the power lines should be favored. General cleaning of dead wood is in order.

Other Recommendations

I should really figure out how to use the chestnuts this fall (the neighbors said we can have all we collect).

Tree Problem 6: Norway Maple street tree

Site: N side of street in the parking strip. (NE Portland)

Biases:

+ Big tree providing much appreciated shade all day in the summer. Significant tree in the neighborhood.

- Norway Maples are getting a bad reputation for being dispersive.

Tree Characteristics

A very large Norway Maple (Acer platanoides) a mature tree with a single trunk DBH 31". Live crown ratio is around 80%.

Tree Health

New foliage looks healthy. Some decay possible at main branch attachments.

Site Conditions

Residential street tree dominating the local canopy. Downslope from a lawn that may receive regular irrigation. No signs of recent site disturbance. Paving under 60% of the dripline, mostly to the North. No evidence of recent changes to paving, fill, or grade work in the dripline. Slope grade flat at base of tree with a 15 degree slope up to the south.

Targets

Two houses, cars.

Tree Defects

Constrained root space by sidewalk, street and nearby slope.

Hazard Rating

Part most likely to fail: branch failure. Moderate failure potential on large parts with significant targets for a hazard rating of 2+3+4 = 9.

Hazard Abatement

Investigate possible decay. Prune to remove end weight of large lateral branches. Monitor. Rationale: Need more data to determine if there is decay to be concerned with. It is not clear to me that cabling would be indicated in this case. "There is a limit to the size and weight cable and brace systems can support".

Other Recommendations

Long term it would be good to consider what will succeed this tree and when.

Tree Problem 5: Tall Black Walnut

Site: W side of my yard (NE Portland)

Biases:

+ Big tree providing much appreciated shade late in the day in the summer. Producer of "Squirrel TV" giving many hours of amusement for us and our dog.

- Shows signs of some pretty aggressive pruning. One falling branch could ruin our whole afternoon.

Tree Characteristics

A tall limbed up old Black Walnut (Julans nigra) a mature tree with a single trunk DBH 29". Live crown ratio is around 40%.

Tree Health

New foliage looks healthy. No significant signs of decay.

Site Conditions

Residential site, between two driveways and next to a low wooden fence, shrub border with no regular irrigation. No signs of recent site disturbance, no paving, fill, or grade work in the dripline, but the driveways and homes occupy probably 30% of the dripline. Slope is level. Between houses on the East and West.

Targets

Two houses, fence, landscape plants.

Tree Defects

Somewhat constrained root space. Signs of severe pruning and growth response from heading cuts. No clear dominant leader. Multiple attachments with large branches.

Hazard Rating

Part most likely to fail: branch failure. Moderate failure potential on large parts with significant targets for a hazard rating of 2+3+4 = 9.

Hazard Abatement

Corrective pruning, possibly requiring cabling (3/8" common) for additional support of week attachments. Rationale: This is a very valuable tree providing a lot of services. Focusing on establishing a sound leader and reducing the problems from the multiple attachments should reduce the risks. Attention should be paid to the growth direction of any significant branch. Annual inspection is recommended.

Other Recommendations

This is a phenomenal tree.

Tree Problem 4: A European White Birch

Site: E side of my backyard (NE Portland)

Biases:

+ One of the few trees on this side of the house. Probably is a nice tree for the neighbor providing shade and screening from the East.

- It and the fence are trying to occupy the same space. It wouldn't be so nice for the neighbor if the tree chopped their house in half.

Tree Characteristics

Presumably a volunteer European White Birch (Betula pendula) a young-mature tree with a single trunk DBH 7". Live crown ratio is around 40%.

Tree Health

New foliage looks healthy. No significant signs of decay.

Site Conditions

Residential site, tucked between the top of a 1 foot retaining wall and a wooden fence, shrub border with no regular irrigation. No signs of recent site disturbance, no paving, fill, or grade work in the dripline. Slope grade is dominated by the retaining wall and otherwise mostly level. Protected by houses on the East and West.

Targets

Two houses, fence, landscape plants, retaining wall.

Tree Defects

Very constrained root space to the West by the retaining wall. Some exposed roots running parallel to the fence. Notch in bark about 1 inch deep and wide at top of fence.

Hazard Rating

Part most likely to fail: root failure. Moderate failure potential on moderate parts with significant targets for a hazard rating of 2+2+4 = 8.

Hazard Abatement

Remove tree. Rational: It seems unlikely the tree roots will be able to provide much anchoring against a strong West wind once the crown gets well established above the roof line. The biggest risk would be a fall storm before leaf drop.

Other Recommendations

There might be time to wait, but it doesn't seem like there is much prospect for this becoming a well adapted tree and the longer we wait the greater the exposure to the environmental causes and the more potential energy for damage should it fail. That said, it is a pretty tree.

Tree Problem 3: An Ash in the corner

Site: NE corner of my backyard (NE Portland)

Biases:

+ This is a spot where I am not likely to be very particular about what grows.

- It looks like this was a volunteer with how close it is to the retaining wall.

Tree Characteristics

The Ash (Fraxinus sp.) in the corner is a young-mature tree with a single trunk DBH 11". Live crown ratio is around 50%.

Tree Health

New foliage looks healthy. No significant signs of decay.

Site Conditions

Residential site, northern aspect, shrub border with no regular irrigation. No signs of recent site disturbance, no paving, fill, or grade work in the dripline. Slope grade is flat. Exposed to prevailing West winds. Half the dripline is under a foot or more of soil behind a retaining wall that looks to predate the tree.

Targets

Fence, retaining wall, landscape plants, garage.

Tree Defects

No signs of root rot, exposed roots, or root pruning. Crown defects: moderate co-dominant leaders. Presumably the roots have made it under the retaining wall and established some anchor on the far side.

Hazard Rating

Part most likely to fail: co-dominant leader. Moderate failure potential on moderate parts with limited targets for a hazard rating of 2+2+1 = 5.

Hazard Abatement

Monitor tree. Consider bracing or cabling with 3/8 inch common grade cable. Rationale: While this tree isn't in an ideal location it is established, comely, and not really likely to do much harm. There is some cracking in the retaining wall that should be monitored.

Other Recommendations

Some pruning should be done to establish a dominant leader.