ISA Certified Arborist — Practice Exam
Diagnosis and treatment: practice questions
Our ISA Certified Arborist bank has 26 questions on this topic. Here are 5 of them with answers; the full mock exam draws from every topic, like the real one.
Question 1
A palm's young new fronds are yellow while mature fronds stay green. Which deficiency is suggested?
- Magnesium
- Iron
- Nitrogen
- Potassium
Show the answer
B. Iron — Potassium: yellow-orange flecking on old fronds; magnesium: yellow band on older fronds.
Question 2
Why is it called Plant Health Care rather than Tree Health Care?
- Because tree care is regulated separately and must not be mentioned in contracts
- It only covers shrubs
- All landscape plants share soil, and treating one affects the others
- It excludes trees
Show the answer
C. All landscape plants share soil, and treating one affects the others — Lawn treatments can affect trees and vice versa.
Question 3
A tree's trunk is flat on one side at the ground. What is a likely cause?
- Too much sunlight on that side
- Normal growth in a tree of that age
- A lightning strike some years earlier
- An encircling (girdling) root
Show the answer
D. An encircling (girdling) root — Excavate to check; check for encircling roots every 4–5 years.
Question 4
Older palm fronds show yellow or orange flecking. Which deficiency is suggested?
- Manganese
- Iron
- Zinc
- Potassium
Show the answer
D. Potassium — Manganese deficiency shows as frizzled new fronds, especially in alkaline soils.
Question 5
Why shouldn't firewood be moved to another town?
- It is illegal to burn wood from other towns everywhere
- Insects and diseases can hitchhike in it
- Moved wood rots faster
- It loses heat value when moved
Show the answer
B. Insects and diseases can hitchhike in it — USDA Forest Service, Tree Owner's Manual.