ISA Tree Pruning Practices Questions and Answers

Question 1

An arborist is tasked with reducing the length of a major limb on a mature maple tree to provide clearance for a nearby structure. To maintain structural integrity and promote proper wound closure, which type of pruning cut is most appropriate for this task?

Accepted Answer

A reduction cut (drop-crotching)

Answer

A reduction cut, also known as drop-crotching, is the correct technique for reducing the length of a large branch. This cut shortens a limb back to a lateral branch that is large enough (at least one-third the diameter of the removed portion) to assume the terminal role, which helps maintain a natural form and promotes compartmentalization. Heading cuts on large branches are a form of topping that leads to decay and weakly attached sprouts. A flush cut removes the branch collar, damaging trunk tissue and inhibiting wound closure. A removal cut is used to take off an entire branch at its point of origin, not to shorten it.

Question 2

A client hires an arborist to prune a dense, overgrown crabapple tree. The client's main objective is to allow more light and air to penetrate the canopy. According to ANSI A300 standards, which pruning type should the arborist specify in the work order?

Accepted Answer

Crown thinning

Answer

Crown thinning is the selective removal of branches to reduce the density of the canopy. This practice increases light penetration and air movement, which addresses the client's objectives. Crown cleaning removes dead, diseased, or broken branches. Crown raising removes lower branches to provide clearance. Crown restoration is used to improve the structure of a tree that has been damaged or poorly pruned previously.

Question 3

While training a young oak tree, an arborist identifies two codominant stems of roughly equal size that are forming a weak, V-shaped union with included bark. To develop a strong central leader and reduce the risk of future failure, the most appropriate long-term strategy is:

Accepted Answer

Subordinate one of the stems by reducing its length.

Answer

Subordination is the best practice for correcting codominant stems in a young tree. By reducing the length of one of the competing stems (using a reduction cut), its growth is slowed, allowing the other stem to establish itself as the dominant central leader. This improves the tree's structure and reduces the likelihood of the weak union failing later in the tree's life. Cabling is typically reserved for mature trees where removal or subordination is not feasible. Removing or heading both stems would be detrimental to the tree's structure.

Question 4

Which of the following is a common, negative consequence of "lion's tailing," a pruning practice where an excessive number of interior and lateral branches are removed from limbs?

Accepted Answer

Increased risk of sunscald on branches and branch failure

Answer

Lion's tailing is an improper pruning practice that displaces foliage to the ends of the branches. This redistribution of weight increases the likelihood of branch failure, especially during wind or ice events. It also exposes the tops of branches to direct sunlight, which can cause sunscald. This practice reduces, rather than improves, structural stability and can trigger stress responses like epicormic sprouting.

Question 5

When removing a large, heavy limb from a tree, the three-cut method is recommended primarily to:

Accepted Answer

Prevent the weight of the branch from tearing the bark down the trunk.

Answer

The three-cut method is a safety and tree health technique used for removing large branches. The first two cuts (an undercut followed by a top cut farther out on the limb) remove the bulk of the branch's weight. This prevents the branch from falling and ripping a long strip of bark from the trunk as the final cut is made. The third and final cut is then made just outside the branch collar to remove the remaining stub, allowing for proper wound closure.

(ISA) ISA Certified Arborist Practice Test

(ISA) ISA Certified Arborist Practice Test

ISA Tree Pruning Practices Questions and Answers