ISA Proper Pruning Practices 2

Question 1

What is the recommended maximum percentage of live crown that should be removed in a single pruning session for a mature tree?

Accepted Answer

25%

Answer

The general guideline is to remove no more than 25% of the live crown in a single pruning session for mature trees. Removing more can stress the tree and trigger excessive epicormic sprouting.

Question 2

What is a 'reduction cut' in arboricultural pruning?

Accepted Answer

Shortening a branch by cutting back to a lateral branch at least one-third the diameter of the removed portion

Answer

A reduction cut shortens a branch by cutting back to a lateral branch that is large enough (at least one-third the diameter) to assume the terminal role and maintain the branch's vascular connection.

Question 3

Why should pruning cuts avoid leaving a 'stub' extending beyond the branch collar?

Accepted Answer

Stubs prevent the tree's natural wound closure process from sealing the wound efficiently

Answer

Stubs prevent efficient wound closure because the branch collar cannot grow over the extended dead wood. The exposed stub becomes an entry point for decay organisms.

Question 4

During which season is pruning generally most detrimental to oak trees in regions where oak wilt is present?

Accepted Answer

Spring through early summer

Answer

Pruning oaks during spring through early summer (April-July) creates fresh wounds that attract sap beetles carrying oak wilt spores. This is the highest-risk period for disease transmission.

Question 5

What is 'lion-tailing' and why is it considered an unacceptable pruning practice?

Accepted Answer

Stripping interior branches and foliage, leaving growth only at branch ends

Answer

Lion-tailing removes interior lateral branches and foliage while leaving tufts of growth at branch ends. This shifts weight outward, increases wind resistance at endpoints, and greatly increases the risk of branch failure.

(ISA) ISA Certified Arborist Practice Test

(ISA) ISA Certified Arborist Practice Test

ISA Proper Pruning Practices 2