CATS Southwest Pest and Disease 2

Question 1

Which fungal pathogen causes the 'witches' broom' symptom commonly observed on hackberry trees in the Southwest?

Accepted Answer

Eriophyid mite and powdery mildew complex

Answer

Hackberry witches' broom is caused by a combination of eriophyid mites and powdery mildew (Sphaerotheca phytoptophila) acting together.

Question 2

The Emerald Ash Borer (EAB) has been detected moving into New Mexico. Which ash species native to the Rio Grande riparian corridor is most at risk?

Accepted Answer

Fraxinus velutina (Arizona ash)

Answer

Fraxinus velutina (Arizona/velvet ash) is the native ash of the Southwest's riparian areas and is highly susceptible to EAB.

Question 3

A homeowner reports that their cottonwood tree has yellowing leaves with dark spots and premature defoliation each summer. The most likely cause is:

Accepted Answer

Marssonina leaf spot

Answer

Marssonina leaf spot (Marssonina populi) is a common fungal disease of cottonwoods causing dark spots and early leaf drop in the Southwest.

Question 4

Zimmerman pine moth larvae cause the most damage to ponderosa pines in the Southwest by:

Accepted Answer

Girdling branches at crotch unions with pitch masses

Answer

Zimmerman pine moth (Dioryctria zimmermani) larvae bore into branch crotches and the main stem, producing large pitch masses that can girdle branches.

Question 5

Which soil condition in Albuquerque's urban landscape most predisposes trees to Phytophthora root rot?

Accepted Answer

Poorly drained, heavy clay or compacted soil with overwatering

Answer

Phytophthora thrives in waterlogged, oxygen-depleted soils, making poorly drained compacted soils with excess irrigation the primary risk factor.

(CATS) Certified Arborist Tree Service of Albuquerque Practice Test

(CATS) Certified Arborist Tree Service of Albuquerque Practice Test

CATS Southwest Pest and Disease 2