Certified Arborist Test Diagnosis and Treatment Questions and Answers — Questions and Answers
Question 1: An arborist inspects a pin oak (Quercus palustris) growing in a landscape with a high soil pH. The newest, youngest leaves show distinct yellowing between the veins, while the veins themselves remain green. What is the most likely diagnosis?
- Nitrogen deficiency
- Anthracnose
- Iron deficiency (Correct answer)
- Drought stress
Correct answer: Iron deficiency
The symptom of interveinal chlorosis (yellowing between green veins) on new growth is a classic sign of iron deficiency. Iron is an immobile nutrient, so deficiency symptoms appear on new leaves first. This condition is common in high pH soils where iron, though present, is chemically unavailable for tree uptake.
Question 2: While examining a declining ash tree (Fraxinus spp.), you discover numerous D-shaped exit holes, each approximately 1/8-inch in diameter, on the trunk and major branches. Which insect pest is the most probable cause of this damage?
- Asian longhorned beetle
- Emerald ash borer (Correct answer)
- Banded ash clearwing borer
- Redheaded ash borer
Correct answer: Emerald ash borer
The D-shaped exit hole is a key diagnostic sign of the emerald ash borer (Agrilus planipennis). Adult beetles create this distinct shape when they emerge from under the bark. Other borers that affect ash trees, such as the redheaded ash borer or clearwing borers, typically create round or oval exit holes.
Question 3: Which of the following is the best example of a cultural control practice within an Integrated Pest Management (IPM) program?
- Releasing parasitic wasps to control an aphid population.
- Applying a targeted insecticide to manage a scale infestation.
- Installing pheromone traps to monitor for pest activity.
- Improving soil aeration and drainage to enhance tree vigor. (Correct answer)
Correct answer: Improving soil aeration and drainage to enhance tree vigor.
Cultural controls in IPM involve modifying the growing environment to make it less favorable for pests and more favorable for the plant. Improving soil conditions enhances the tree's natural defenses, making it more resilient to pest and disease pressure. Releasing wasps is biological control, applying insecticide is chemical control, and using traps is for monitoring.
Question 4: A client points out a large, woody, shelf-like fungal growth, known as a conk, at the base of a mature maple tree. The tree's canopy currently appears healthy. What does the presence of this conk signify?
- It is a harmless, superficial fungus living only on the outer bark.
- The tree has an advanced stage of internal wood decay. (Correct answer)
- The tree is suffering from a minor foliar disease.
- It is a sign of recent, severe insect borer activity.
Correct answer: The tree has an advanced stage of internal wood decay.
A conk, or basidiocarp, is the reproductive fruiting body of a fungus that is causing internal decay. Its presence indicates that a significant amount of wood decay is already occurring inside the trunk or roots, even if the canopy still appears healthy. This is a critical indicator for assessing tree structural integrity.
Question 5: An arborist must fertilize a mature tree in a heavily compacted clay soil lawn. Which application method is most effective for delivering nutrients directly to the root zone and bypassing the compacted surface layer?
- Surface broadcast of granular fertilizer
- Foliar spray application
- Subsurface liquid injection (Correct answer)
- Trunk implantation of fertilizer plugs
Correct answer: Subsurface liquid injection
Subsurface liquid injection uses high pressure to place liquid fertilizer directly into the root zone, typically 8-12 inches deep. This method is highly effective in compacted soils as it bypasses the turf and compacted surface layer, reduces runoff, and helps aerate the soil. Surface application is ineffective on compacted soil, foliar sprays are for temporary micronutrient issues, and trunk implants are for specific deficiencies, not general fertilization.
Question 6: Which of the following observations is most characteristic of an abiotic disorder rather than a biotic problem?
- Symptoms appear suddenly and uniformly across several different, unrelated plant species in one area. (Correct answer)
- The problem seems to spread progressively from one tree to another over time.
- Fungal hyphae or insect frass is visible upon close inspection of damaged tissue.
- Symptoms are localized to a single branch on an otherwise healthy tree.
Correct answer: Symptoms appear suddenly and uniformly across several different, unrelated plant species in one area.
Abiotic disorders are caused by non-living factors like chemical drift, frost, or drought. A key diagnostic pattern is the uniform appearance of symptoms on multiple, unrelated species in a specific area. Biotic problems, caused by living organisms like insects or fungi, are typically species-specific and tend to spread from plant to plant over time in a more random pattern.
Certified Arborist Test Diagnosis and Treatment Questions and Answers
An arborist inspects a pin oak (Quercus palustris) growing in a landscape with a high soil pH.
The newest, youngest leaves show distinct yellowing between the veins, while the veins themselves remain green.
What is the most likely diagnosis?