ISA Pest and Disease Diagnosis Questions and Answers

Question 1

An arborist observes that several different and unrelated tree species in a parking lot island are all showing similar symptoms of marginal leaf scorch, stunted growth, and early fall color.
What is the most likely cause of these symptoms?

Accepted Answer

An abiotic disorder such as soil compaction or heat stress

Answer

An insect infestation specific to one species

Answer

A fungal leaf spot disease

Answer

A bacterial blight targeting a specific plant family

Question 2

Which of the following is a "sign" of a pest or disease, as opposed to a "symptom"?

Accepted Answer

Emergence holes from a wood-boring insect

Answer

Wilting leaves on a branch

Answer

Cankers forming on a stem

Answer

Yellowing of the foliage (chlorosis)

Question 3

For a biotic disease to develop in a tree, three components must be present. This concept is commonly known as the disease triangle. What are these three components?

Accepted Answer

A susceptible host, a virulent pathogen, and a favorable environment

Answer

An insect vector, a weak host, and high humidity

Answer

A nutrient deficiency, a pathogenic fungus, and compacted soil

Answer

The right temperature, the right moisture, and a point of entry

Question 4

Upon inspecting a birch tree, an arborist notices distinct D-shaped exit holes on the trunk and significant canopy dieback starting from the top down. This evidence is most characteristic of which type of insect pest?

Accepted Answer

Flatheaded borers (e.g., Bronze Birch Borer)

Answer

Aphids

Answer

Japanese beetles

Answer

Tent caterpillars

Question 5

An arborist is called to assess a declining oak tree. At the base of the tree, near the soil line, they find a fan-shaped mat of white mycelium under the bark. The wood has a distinct mushroom-like smell. These signs are most indicative of which common root rot pathogen?

Accepted Answer

Armillaria root rot

Answer

Fire blight

Answer

Powdery mildew

Answer

Verticillium wilt

Question 6

Which of the following actions best represents the principle of using cultural controls within an Integrated Pest Management (IPM) program?

Accepted Answer

Improving soil drainage and sanitation to reduce the likelihood of root rot diseases

Answer

Releasing predatory insects to control an aphid population

Answer

Spraying a targeted insecticide when pest levels exceed a threshold

Answer

Hand-picking caterpillars off a small ornamental tree