Too often, pruning is urgent damage control, or catch-up work on long-neglected trees. Ideally, it is a long-term and low-intensity process beginning when the tree has begun to form branches.
All too commonly landscape trees have structural problems making them susceptible to failures that could have been prevented with thoughtful pruning early on.
Here are a few examples:
- Scaffold branches crowded too close together. This concentrates physical strain at one point, making the trunk and branches subject to breaking.
- Branches with a narrow “V” angle of attachment and “included bark” — branch bark pinched against trunk bark. It results in the tree wounding itself over time and branches failing at the weak attachment.
- High “branch aspect ratio”: Branches nearly equal to the trunk diameter have an inherently weak attachment. The trunk cannot get a good grip on a branch that is nearly equ
- al to it in diameter.
Right now is a good time to be shopping for young shade trees for late winter planting, so buyer beware of defects before making a purchase! Some common defects are not easily corrected by pruning.
At planting time prune only to remove dead, diseased or broken branches. Let the new tree grow for a year, then start pruning to develop good structure.
Years ago, after viewing an International Society of Arboriculture video on “Young Tree Pruning” I devised a mnemonic for remembering the objectives: the “CLPST” method. It goes like this:
C: Clean. Prune for cleaning to remove dead, broken, dying and diseased branches.
L: Leader. Retain a central leader or a branch that will serve as the main axis. The leader is obvious and dominant in some trees like coastal redwoods, but gradually divides into many branches in other species.
P: Permanent lowest limb. Its height on the trunk, diameter in relation to trunk diameter, and orientation in the landscape are critical to the physical strength and function of the tree.
S: Scaffold branches, the architecture of the tree. These emerge over a period of years as the tree grows from sapling to maturity.
T: Temporary branches: These might be too low on the trunk to serve as the first permanent branch, or too crowded to serve as scaffold branches, but retaining and controlling some of them can protect the trunk from sun injury or physical damage, and feed the trunk, helping to build strength. They should be kept short and removed gradually over a period of years.
Cleaning is rarely necessary for a new tree from the nursery. This step should generally be the only pruning in the first year after planting.
The first permanent branch elevation is critical for clearance where trees are adjacent to streets and walkways. Its compass orientation can be important for aesthetics. The angle from which the tree is most often viewed should show off this crucial element of structure. Look at classic bonsai trees. They typically have a “front” with the first branch growing to one side, not directly forward or to the back.
Scaffold branches on small trees, like dogwoods, might already exist on a newly transplanted tree. But scaffolds on large shade trees should be spaced farther apart and might not emerge from the leader for many years after planting. Their diameter should be no larger than half the diameter of the leader/trunk at their point of attachment.
Temporary branches should also be less than half the diameter of the leader and pruned to keep them short. They can be removed gradually as the tree matures.
The CLPST system also applies to developing the structure of each scaffold branch just as it does to the whole tree.
This systematic method can help pruners make sense of the process of developing good tree structure over time.
WATCH NOW: WHY DO SOME TREES AVOID TOUCHING EACH OTHER?
CHECK OUT: MOST READ POLICE BRIEFS ON NAPAVALLEYREGISTER.COM
Most-read police briefs on NapaValleyRegister.com
Here is a roundup of other police and fire reports in Napa County.
Napa police received multiple reports of a man destroying property as he walked through the central city.
When American Canyon police spotted a vehicle without a license plate parked on Highway 29, they discovered that the Toyota Camry had been rep…
A former employee at Wendy's restaurant on Trancas Street was arrested after a customer discovered a video camera in a bathroom stall.
FEB. 22: Two catalytic converter theft suspects were behind bars after a north Napa car owner interrupted thieves caught in the act of removin…
Napa Police were called to Raley's supermarket on Soscol Avenue where staff had detained a man suspected of stealing alcohol.
FEB. 26: American Canyon police took a report of a catalytic converter theft on Klamath Court, then located surveillance camera footage of the…
FEB. 17: City of Napa police responded to a report of a stolen vehicle at the 7-Eleven store at Silverado Trail and Clark Street. The victim l…
FEB. 18: A man driving a stolen vehicle fled from Napa County Sheriff’s officers, lost control and drove into a city of Napa house.
Catch up on Napa County's top news stories
In case you missed it, here is a look at the most-read stories on NapaValleyRegister.com.
From poverty to Stanford: One Napan's journey thanks to If Given A Chance.
The Olney family is being sued for the wrongful death of a man who died when a vehicle crashed into an irrigation pond at their property in 2020.
A trio of “luxury lofts” — homes that could sell for as much as $2 million each — have been proposed for a downtown Napa block.
The controversial residential placement of an elderly man classified as a sexually violent predator took a dramatic turn Monday when a judge o…
Take a sneak peek inside a new Napa tiki bar, Wilfred's Lounge, planned to open this summer.
The council framed the issue as involving public safety, not free speech. Demonstrators can still protest, but must observe new boundaries, th…
The Planning Commission urges developers of Soscol Square, which is to host Kohl's and Chick-fil-A, to upgrade the Napa shopping center's design.
This Napa family has made a great escape: they're living on and sailing a catamaran, going where the wind takes them. Right now, that's the Bahamas.
A well-known and historic downtown Napa house, home to an early city businessman and later Napan Francis “Jeep” Sanza and his family, has been…
The vast majority of individuals who originally tested positive received negative retests. State officials are conducting separate retesting i…