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^MONTANA DEPARTMENT OF NATURAL
RESOURCES AND CONSERVATION

DIVISION OF FORESTRY

INSECT AND DISEASE REPOR

Montana State Library

Missoula, Montana 59801 IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIWII1 llllllllllllllll 949.33

Report 78-2 ''sOSeT 1006 4862 8 ^rch 1978

FOREST INSECT AND DISEASE CONDITIONS

IN MONTAHA-1 977 STATE D0«WS COLLECTION

by MAY 3 1 ?978

Steve Kohler1 Mopr.*^ state Lm/wv

Qon r i , "'"'''I

., ;-'° E tyrukk Ave.
"■'v- Montana 59601
Great potential exists in Montana for increasing timber production and for preserving
forests for recreational and aesthetic uses by reducing damage and tree losses caused
by forest pests. Under the Insect and Disease Control Prooram, responsibilities of
the Division of Forestry of the Department of Natural Resources and Conservation fall
into four basic areas:

1. Encouraging the use of preventive measures of demonstrated effectiveness on
State and private forest lands as the first line of defense against destructive
insects and diseases.

2. Operating a detection program with surveys of sufficient intensity and frequency
to ensure prompt discovery of forest insect and disease outbreaks on State and
private lands.

3. Providing for thorough biological, cost benefit., and environmental impact
evaluations of insect and disease outbreaks on State and private forest lands
as a basis for deciding for or against suppression.

4. Practicing and encouraging the use of effective means of forest insect and
disease control which provide the least potential hazard to man, domestic animals;
wildlife, and other components of the natural environment.

PROGRAM ACCOMPLISHMENTS IN 1977

1. The annual cooperative aerial insect and disease detection survey was conducted
on a total of 2,134,400 acres of forest lands, including private commercial
ownerships, and the Swan River, Stillwater, and Thompson River State forests.
Insect and disease infestations were mapped, and copies of the completed maps
were made available to the U.S. Forest Service and the Division of Forestry
area offices.

Forest Insect and Disease Section Supervisor, Montana Department of Natural Resources
and Conservation, Division of Forestry, Missoula, Montana.

>

2. Over 50 field detection reports and damage samples were received from Division
field personnel and private landowners for identification and recommendations.

3. An evaluation of western spruce budworm infestations on 343,920 acres of State
and private lands was completed.

4. Work toward developinq methods for predicting larval populations of Douglasfir
tussock moths from numbers of adult male moths caught in oheromone-baited sticky
traps was continued. In 1977, four different pheromone concentrations were
tested on each of eight plots in the Missoula and Flathead valleys.

5. A study to determine the effectiveness of cacodylic acid herbicide in causing
mountain pine beetle brood mortality was completed. Effects on beetle brood
mortality were assessed in the spring of 1977 and compared to the 1976 results.
The study will be reported in Insect and Disease Report 73-3.

6. A detection survey for the smaller European elm bark beetle (the vector of Dutch
elm disease) was conducted in nine Montana cities using sticky traps baited
with Multilure pheromone. The results of that survey were presented in Insect
and Disease Report 70-1, Detection Survey for the Smaller European Elm Bark
Beetle in Montana Using Pheromone-Baited Sticky Traps.

REVIEW OF CONDITIONS

Bark Beetles

Mountain Pine Beetle, Dendroctonus ponderosae (Hopk.)

Infestation levels remained high with substantial increases in many mature lodgepole
pine stands and overstocked second-growth ponderosa pine stands (Figure 1).

Heavy mortality in lodgepole pine continued in the Gallatin River drainage south of
Bozeman. Approximately 146,000 acres are currently infested, at an average of over
30 trees per acre. Since 1969, over 350 million board feet of timber in the Gallatin
River drainaae have been killed by mountain pine beetles: over 4 million trees could
be killed in' 1978. The buildup ratio of 1976 to 1977 attacked trees was 1:2.8.

The mountain pine beetle-infested area around "est Yellowstone and Heboen Lake
reached 78,000 acres in 1977. The buildup ratio of trees killed in 1975 to trees
killed in 1977 was 1:8. Approximately 1.7 million trees containing 175 million board
feet of timber are currently infested. Predictions are that over 3 million trees
will be killed on approximately 180,000 acres in 1978.

Beetle activity increased markedly in the North Fork drainage of the Flathead River
in 1977. Currently infested in Glacier National Park are 142,300 acres, and in the
Coal Creek State Forest area 10,215 acres of national forest lands, 13,470 acres
of private lands, and 3,915 acres of State-owned lands are infested. Losses of
timber to date on these lands total 284,419,600 cubic feet. The buildup ratio of
trees killed in 1976 to trees killed in 1977 was approximately 1:7. Substantial
increases in both number of acres infested and number of trees killed are expected
in 1978.

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ALB E K T A

Figure 1. Areas of mountain pine beetle infestation, Montana, 1977

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Losses continued in lodgepole pine on State, private, and Federal lands in the
Meadow Creek, Lazier Creek, and Thompson River drainages north of Thompson Falls.
Beetle activity continued to increase near Fish Trap Lake and in Twin Lakes Creek
and Fish Trap Creek drainages. The infestation now covers approximately S,000 acres.

In the Bitterroot River drainaae, an infestation on the north face of Shook Mountain
covered approximately 1,200 acres in 1977, and over 103,000 lo-.'oepole and ponderosa
pines, containinq 4,325,520 board feet were killed. Approximately 1,100 ponderosa
pines were killed near Sulu in the Cameron Creek drainage and near the East Fork of
the Bitterroot River, larqely on State and private lands.

Over 1 million lodqepole pines were killed in 1977 in the Jack Creek infestation
east of Ennis, which now covers over 4,000 acres.

In the Upper Yaak River drainage north of Libby, the mountain pine beetle outbreak
on predomonantly U.S. Forest Service lands covers approximately 13,000 acres.

Continued ponderosa pine losses to mountain pine beetles occurred on State, private,
and Federal lands in the Lewis town area. Tree kill inn increased in the Moccasin
and Little Snowy mountains, in Uaiden Canyon in the Judith Mountains, and in Big
Spring, Castle, Casino, Beaver and Rock Creek drainaqes of the Big Snowy Mountains.
Continued activity was noted in McCartney and Flatwillow Creek drainages.

Some losses have occurred in second-qrowth ponderosa pine stands on the Fort
Belknap Indian Reservation in the Little Rocky Mountains. Current infestation
levels average 7.1 trees per acre, and an estimated 4,560 trees have been killed
since 1975.

Losses in ponderosa pine continued in the Blackfoot River and Clark Fork drainaaes.
Beetle activity persisted north of Potomac, near Greenouqh in the Fish Creek drainage,
in the Bearmouth area, and in Johnson and Butler Creek drainages northwest of Missoula,

Approximately 3,300 ponderosa pines were killed in the Wolf Mountains near Lodge
Grass on the Crow Indian Reservation.

A mountain pine beetle outbreak of approximately 10 acres on State lands occurred
next to log decks at the American Timber Products mill in Olney, apparently the
result of beetles flying from infested logs decked in the yard to trees in the
adjacent stand of lodgepole pine.

Douglasfir Beetle, Dendroctonus pseudotsugae (Hopk.)

As in past years, activity by this beetle remained generally low throughout the
State. Scattered groups of overmature Douglasfir were killed.

Pine Enqraver Beetle, Ips sp.

Damage by pine engraver beetles increased substantially in 1977, probably due to
drouaht conditions that prevailed durinq the year causing strees in the trees and
making them more susceptible to attack. Activity occurred mostly in ponderosa
pine, with losses occurring near Missoula on Blue Mountain' in Rattlesnake, Grant,

si f .- • ':.

0'Briens and Lolo Creek drainages; along the Clark Fork near Bonner, Turah, and
Big Flat- on both sides of the Bitterroot Valley; and in several areas of the Flathead
Valley, Including Poison, Rollins, and Pablo. Damage due to ennraver beetles was
intensified by disturbance to tree root systems through road building and home
construction in the Blue Mountain, Grant Creek, and Rattlesnake Creek areas, with
some losses of high-value shade trees occurrino.

Spruce Beetle, Dendroctonus rufipennis (Kirby)

Beetle-containing spruce blowdown remainino from 197G in the Antice area of the

Stillwater State Forest, as well as 1977 blowdown, was lamely removed through

salvage. Prompt removal of down spruce through such salvage has prevented outbreaks
in standing trees.

Fir Engraver, Scolytus ventral is (LeConte)

Activity in Douglasfir by fir engraver declined in 1977. Surveys in 1978 may
detect increases in the number of trees killed as a result of low rainfall during
1977. Fir engraver activity has occurred in the lower Thompson River drainage;
near Olney, IJhitefish Lake, Lake Blaine, and Echo Lake in the Ka 11 spell area;
around Swan Lake: and in the Lost, Soup, Cilly, and Goat Creek drainanes in the
Swan River State Forest.

Defoliators
Western Spruce Budworm, Choristoneura occidental is (Freeman)

Visible defoliation in -iontana was detected on 2,992,655 acres of dounlasfir, true
fir, and spruce in 1977 (Figure 2), a 20-percent increase over the 2,496,274 acres
defoliated in 1976. Increases in the number of acres defoliated occurred in the
Bitterroot, Custer, Gallatin, Helena, Kootenai, Lewis "; Clark, and Lolo national
forest areas and within the Flathead Indian Reservation. Defoliated acreaaes
decreased in the Beaverhead, Deer Lodge, and Flathead national forest areas.

Douqlasfir Tussock doth, Orgyia pseudotsunata (HcD.)

do defoliation from Oounlasfir tussock moth was detected in iontana in 1977. Hoth
populations remained low. do larvae were recovered from lower branch beating samples
on eight study plots in the Missoula and Flathead valleys, even though several
hundred trees were sampled and adult male moths were
sticky traps at all of the plot locations.

cauoht

in oheromone-haited

Larch Casebearer, Coleophora laricella (Hbn.)

Defoliation from larch casebearer increased in 1977;. the most severe damage was
detected in low-elevation stands. In the Flathead national Forest area, there were
23,196 acres of State and private lands and 56,590 acres of Federal lands defoliated.
There were 27,600 acres of defoliation on the Flathead Indian Reservation.

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Other Insects

Pine Bark Aphid, Pineus sylvestris (Annand

..apinq tne trees tnnjunn snearui'ii sbvcibi ycwij »i «■»*.. ..v.* .--- on
many trees. Damage was detected too late in 1977 to attempt control, but should
populations persist in 1973, suppression by aerial sprayino of insecticide may be
initiated by the landowners.

PonJerosa Pine Needle uiner, Coleotechnites sn.

Approximately 10,000 acres of ponderosa pine were lamaned on the Flathead Indian
Reservation near Arlee. A nrove of ponderosa pines on the University of i .ontana
Campus, Missoula, was also affected.

Diseases

Fir-Fireweed Rust5 Puccini as trum epilobii (otth.)

This disease affected scattered subalpine fir on several thousand acres between
upper Antice Creek and Upper Whitefish Lake. The damane was heavier near entice
Creek.

Pine needle Cast Fungus, Loohodermella concolor (Dearn.) barker

Damaae occurred on several thousand acres of lodqepole pine inp th? ntzsimmons
Creek drainage and in the upper Stillwater River irainaqe of we Stillwater State
Forest Lodgepole pines were also damaged in a lame area between Lincoln and
Roqers Pass, with some mortality to small regeneration. Heavy damane was also
noted in Gory Creek and Nickel Bar Gulch of the Ruby Creek drainaoe, soutnwest of
Wisdom.

Dutch Elm Disease, Ceratocystis ulr.ii (Buism.) C. itoreau

Dutch elm disease funcius was recovered from dead and dying American elms south of
Florence, Ravalli County, in 1977. So far, the disease is restricted to this
locality and Missoula,

To determine the neneral distribution in Montana of the orincioal vector of the
disease, the smaller European elm bark beetle, Scojyti^ multi striata s ( iarsnam)3
nine cities were surveyed usinq pheromone-baitei sticky traps. Beetles were
recovered from trans in Billing, Great Falls, Livinoston, Rozeman, files City,
Glendive, and Kalispell. do beetles were trapped in Lewis town or Sidney. Dutcn
elm disease has not been detected in any of the cities where populations of elm bark
beetles occur, but it is probably just a matter of time before the disease spreads
to elms in these cities.

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