Southwest Pest and Disease Flashcards

Thousand cankers disease (TCD), which threatens black walnut across the US, is caused by a fungus vectored by which insect?

Answer: Walnut twig beetle (Pityophthorus juglandis)

Thousand cankers disease is caused by the fungus Geosmithia morbida, vectored exclusively by the walnut twig beetle (Pityophthorus juglandis).

A certified arborist in New Mexico is evaluating a mature ponderosa pine with significant needle cast. Which pathogen commonly causes Dothistroma needle blight on ponderosa and other pines in the Southwest?

Answer: Dothistroma septosporum

Dothistroma septosporum causes Dothistroma needle blight, producing tan to reddish-brown banding on needles followed by premature needle cast.

Which management strategy best reduces the risk of bark beetle attacks on stressed pines in an Albuquerque urban landscape during drought?

Answer: Providing deep, infrequent supplemental irrigation to reduce drought stress and maintain resin flow

Maintaining tree vigor through deep supplemental irrigation is the most effective cultural practice for drought mitigation, as healthy pines produce resin that repels and kills invading bark beetles.

A homeowner reports sticky residue and white waxy masses on their blue spruce branches. The pest is most likely:

Answer: Cooley spruce gall adelgid (Adelges cooleyi)

Cooley spruce gall adelgid produces white woolly wax masses on spruce needles and stems and completes part of its life cycle on Douglas-fir.

Phytophthora cinnamomi root rot is particularly devastating to which ornamental tree commonly planted in Albuquerque landscapes?

Answer: Arizona cypress (Cupressus arizonica)

Arizona cypress is highly susceptible to Phytophthora cinnamomi, which thrives under overwatering conditions common in urban landscapes.

During an inspection of a Rio Grande cottonwood, an arborist finds roughened, corky bark with reddish-brown streaking in the sapwood beneath. The most likely diagnosis is:

Answer: Cytospora canker caused by Cytospora chrysosperma

Cytospora chrysosperma is the most common canker pathogen of cottonwoods and poplars in the Southwest, causing bark roughening and discoloration in the wood.

The best time to apply a preventive trunk spray of pyrethroid insecticide to protect a high-value ponderosa pine from mountain pine beetle attack is:

Answer: Spring, just before adult beetle flight and attack season begins

Preventive pyrethroid sprays must be applied to the trunk before adult beetles initiate attacks in spring, as they are ineffective once beetles have penetrated the bark.