Forest Pests and Diseases near Lewistown, MT

Amy Eckert

Forest Pathologist

Insects1. Mountain pine beetle : PP, LPP, and WP

2. Red turpentine beetle: PP,LP, and piñon

3. Douglas-fir bark beetle: Douglas-fir

4. Pine engraver beetle (Ips): pines

5. Western spruce budworm: Douglas-fir

6. Bronze birch borer: birch

Mountain pine beetle : PP, LPP, and WP

Bluestain fungal spores

Mountain pine beetle : PP, LPP, and WP

Look for small pitch tubes in bark and woodpecker feeding

Red turpentine beetle: PP,LP, and piñon

Large pitch tubes: Combination of resin, bark dust, and frass

Douglas-fir bark beetle: Douglas-fir Look for insect frass or boring dust in bark crevices

Best beetle proofing strategy:

Recognize high hazard situations and act to reduce potential beetle infestations

What forest/tree conditions are most favored by beetles?

What forest/tree conditions are most favored by good grass growth and grazing?

Why can’t we just spray?

Target stand = 80-100 sq. ft basal area

10”tree= 150-180 tpa (16’x16’ = 170 tpa)

12”tree= 100-125 tpa (18’X20’ = 121 tpa)

Infects slash and small pine trees.

Pine engraver beetle (Ips): pines

Look for tiny holes in bark and red boring dust on slash

Best ips prevention?

Western spruce budworm: D-F, spruce and WL

Adult

Larvae

Eggs

Web-like material on branch ends, needles turn brown

Best spruce budworm prevention strategy:

Enhance budworm predator habitat (birds, carpenter ants) how?

Maintain tree health and vigor- how? why?

Maintain adequate spacing and reduce thick understory regeneration

Plant resistant trees such as pine and larch

Bronze birch borer: birch

Top kill, branches die from the top down

Keep birch healthy and vigorous: use iron enriched fertilizer, water. Prune infected branches.

Diseases1. Aspen cankers and decline

2. White pine blister rust: WP

3. Western gall rust: LP and PP

4. Fire blight: apple species

Aspen Trees

Cytospora canker of aspen

Weak pathogen

Aspen Trees

Cytospora canker on aspen stem with insect frass. Some insects that are attracted to aspen are: poplar borer, bronze poplar borer, bark beetles, ambrosia beetle.

Insect Frass

Weak insects

White pine blister rust

Native or exotic?

Ribes

Cotoneaster hedge

with fire blight infection

Peeling bark

Canker-like twig discoloration

General scorched-like appearance of infected twigs and leaves

Fire Blight

Western Gall Rust: Lodgepole and Ponderosa

Infects young shoots and forms galls on branches, cankers and stems

Remove infected trees during thinning. Increase air flow in stand