Forest Insect and Disease Conditions

British Columbia & Yukon 1987

C.S. Wood

G.A. Van Sickle

L.M. Humble

Canadian Forestry ServicePacific Forestry Centre

BC-X-296

1987

Canadian Forestry ServicePacific Forestry Centre

506 West Burnside RoadVictoria, B.C.

V8Z 1M5

Minister of Supply & Services Canada, 1987ISSN 0830-0453

ISBN 0-662-15846-6Cat. No. Fo46-17/296E

Microfiches of this publication may be purchased from:

MicroMedia Inc.Place du Portage

165, Hot el-de-VilleHull, Quebec

J3X 3X2

Abstract

Resume

This summary of forest pest conditions in BritishColumbia and the Yukon Territory in 1987 high-lights pests that are or may become major forestmanagement problems. It was compiled fromrecords and field reports of 11 Forest Insect andDisease Survey rangers with contributions fromforest agencies, researchers, and industry. Morethan 40 forest pests are discussed and some pre-dictions are made for 1988.

Le present résumé sur les ravageurs des forets dela Colombie-Britannique et du Yukon, en 1987,porte sur ceux qui posent ou peuvent poser degraves problemes aux amenagistes. II synthetiseles observations et les rapports de 11 techniciensdu RIMA, en integrant les contributions deschercheurs, des organismes et de l'industrieforestiere. Plus de 40 ravageurs font l'objet dediscussion et de previsions pour 1988.

5

Contents

Page

ABSTRACT/RESUME 3INTRODUCTION 7SUMMARY 8PINE PESTS 10

Mountain pine beetle 10Pinewood nematode 14Pine needle sheathminer 14Pine needle diseases 15A conifer weevil 15

DOUGLAS-FIR PESTS 16Western spruce budworm 16Douglas-fir tussock moth 19Douglas-fir beetle 19A Douglas-fir coneworm 19

SPRUCE PESTS 20Spruce beetle 20Spruce aphid 20Spruce weevil 20Spruce bud insects 21Northern spruce engraver beetle 21

TRUE FIR PESTS 21Budworms 21Balsam woolly adelgid 23Western balsam bark beetle 23

HEMLOCK PESTS 25Western blackheaded budworm and hemlock sawfly 25Western hemlock looper 28

LARCH PESTS 28Larch casebearer 28Larch sawfly 29Larch needle diseases 29Larch budmoth 29

MULTIPLE HOST PESTS 30Black army cutworm 30Cone, seed, and seed orchard pests 31Pests of young stands 32Animal damage 32Climatic injury 33Acid rain monitoring 33Fume damage 33

DECIDUOUS AND ORNAMENTAL TREE PESTS 34Tent caterpillars 34Gypsy moth 35Satin moth 35Western winter moth 35Winter moth 36Poplar leaf and shoot blight 36A birch leaf skeletonizer 36Poplar and willow borer 36

NEW RECORDS OF OCCURRENCE AND DISTRIBUTION 37

7

Introduction

The Forest Insect and Disease Survey (FIDS) ofthe Canadian Forestry Service (CFS) is responsi-ble for producing an annual national overview ofimportant forest pest conditions and their impli-cations. In the Pacific Region, general surveysare conducted to detect and monitor importantforest insects, diseases, and environmental fac-tors. Additionally, surveys and records are main-tained in support of quarantine programs, forestresearch projects, and herbaria and insect collec-tions. Surveys are conducted with the coopera-tion of the British Columbia Forest Service,other federal and provincial agencies, municipali-ties, the forest industry, educational centers, andresearch programs at the Pacific Forestry Centreand other CFS centers nation-wide.

This regional report reviews the status andimpact of major forest insects and diseases andthe effects of environmental factors on coniferand broadleaf forests in British Columbia and theYukon Territory in 1987, and forecasts trends ofsome pests and their potential damage in 1988.Damage trends and expansion of infestations canbe determined by comparison to previous years'reports.

Throughout this report, the subjective terms"light," ',:moderate," and "severe" are used todescribe the level of total defoliation. Unless oth-erwise stated, these are defined as: 1 to 25%, 26to 65%, and more than 66% defoliated,respectively.

The report is compiled from information ob-tained largely from field observations and

records of 11 FIDS rangers collected during theirfield assignments from late May to October in sixprovincial forest regions and the Yukon Terri-tory. More detailed information on the status offorests pests is available in reports compiled bythe following FIDS rangers:

Cariboo — Dick AndrewsKamloops — Bob Erickson and Jim

LorangerNelson — Peter Koot and John VallentgoedPrince George — Rod Garbutt and Rod

TurnquistPrince Rupert — Leo Unger and Alan

StewartVancouver — Nick Humphreys and Rob

FerrisYukon Territory — Rod Turnquist

Other staff of the Forest Insect and DiseaseSurvey project in 1987 were:

Allan Van Sickle — Head, Forest Insect andDisease Survey

Colin Wood — Chief RangerJoan Strobbe — SecretaryLee Humble — Entomologist — insectary

and collectionBob Duncan — Insectary Technician —

diagnosticsErika Pass — Insectary Technician —

rearing and data baseAl Funk — Pathologist — disease

identificationDaphyne Lowe — Herbarium Technician

8

Summary

The record mild 1986-87 winter, above-averagesummer temperatures, a record number of daysof sunshine, and below-average rainfall through-out most of British Columbia in 1987 were con-ducive to high survival of overwintering insectpopulations and successful development ofmajor forest pests.

Mountain pine beetle was the most damagingforest insect in British Columbia and killedmature pine in 8866 infestations over more than66 470 ha in six forest regions from the interna-tional border to northeast of Prince Rupert. Infes-tations expanded in the Prince Rupert and PrinceGeorge regions and in the Cariboo Region forthe first time in 2 years, but declined overall else-where. Mature pine killed before 1985 over 1.8million ha in the Cariboo Region and 75 000 hain the Kamloops Region are legacies of morethan 10 consecutive years of infestation. Highnumbers of mainly predisposed mature pinewere killed by increased pine engraver beetlepopulations in five forest regions. Pine needlesheathminer again severely defoliated newlodgepole pine shoots in widely scattered standsin three forest regions. Pine stem, branch, andneedle diseases were common and widespread inyoung and some older interior pine stands. Pine-wood nematode, a factor limiting exports ofwood chips but not currently a pest causing con-spicuous damage to forests in British Columbia,was extracted from only 12 conifers and fromone adult woodborer. Increased numbers of coni-fer weevils defoliated new shoots of immaturelodgepole pine in the Cariboo Region.

More than 834 000 ha of interior Douglas-fir for-ests, mostly in the Kamloops Region, were defo-liated by western spruce budworm in 1987. Thiswas more than double the area affected in 1986and was the most expansive outbreak in morethan 50 years. The major expansion was in theNorth Thompson and Adams river drainages andthe north Okanagan Valley of the KamloopsRegion, in the eastern Cariboo Region and nearPemberton in the Vancouver Region. Feeding insmall areas of Douglas-fir previously defoliatedin the southwestern part of the Nelson Region,and in large areas east and north of Ashcroft in

the Kamloops Region, decreased. Larval parasi-tism was low (average 18%) and egg mass num-bers forecast mostly severe defoliation in 1988.

About four times as many male adult Douglas-firtussock moths were collected in twice as manypheromone-baited sticky traps as in 1986. Nolarvae or egg masses were found. Some defolia-tion may occur west of Kamloops and in thenorth Okanagan Valley in 1988; an outbreak maytart in 1989. The number of mainly overmature

predisposed Douglas-fir killed by Douglas-firbeetle remained at endemic levels throughoutthe host range.

The overall decline in area and volume of maturewhite and Engelmann spruce killed by sprucebeetle in British Columbia continued for the fifthconsecutive year. Of 63 separate infestationstotalling 3300 ha, most were in the Kamloopsand Prince George regions. Mature spruce werevery lightly strip-attacked along the Haines Roadnorth of the Alaska border in the Prince RupertRegion where attacks have fluctuated periodicallysince 1983. The general population decline is ex-pected to continue in 1988.

Mature 1-year cycle eastern spruce budwormdefoliated alpine fir and spruce over 59 400 hanorth and west of Fort Nelson and into theYukon Territory, down from 95 000 ha in 1986.Immature 2-year cycle budworm larvae defoliat-ed new shoots of alpine fir and spruce over48 250 ha in 180 infestations in the PrinceGeorge, Kamloops, and Cariboo regions. In-creased populations were forecast in 1986 basedon egg samples, but the defoliation was not ex-pected to be as widespread until 1988 when thelarvae mature. Mature "off-year" 2-year cyclebudworms lightly defoliated alpine fir and spruceover 11 500 ha in the Nelson Region, mainly inthe East Kootenay and in the Arrow Lakes drain-age in the West Kootenay. Egg samples indicatecontinuing moderate to high numbers of larvaein 1988.

In the third consecutive year of outbreak, west-ern blackheaded budworm and hemlock sawflylarvae defoliated mature and immature western

9

hemlock over 14 100 ha on the Queen CharlotteIslands, down two-thirds from 1986. Populationsnear Kitimat collapsed with no defoliation. Fluc-tuating populations in the eastern part of thePrince Rupert Region lightly defoliated newshoots of white spruce and alpine fir from NadinaRiver to near Hazelton. Populations increased inhemlock stands in Wells Gray Provincial Park inthe Kamloops Region in five pockets totalling1100 ha and on 5 ha near Holberg on VancouverIsland. Based on budworm egg counts, reducedpopulations and decreased defoliation of hemlockon the Queen Charlotte Islands is forecast in1988. Parasitism of budworm larvae averaged 6%at Honna Valley. Defoliation is not expected nearKitimat, but there could be light defoliation inhemlock stands near Holberg and on spruce andalpine fir in the eastern part of the Prince RupertRegion. Sawfly prepupal mortality averaged 54%but defoliation is still forecast at 10 of 27 loca-tions, mostly on Graham Island. Growth impactstudies will resume following the collapse of theoutbreak. A new infestation of western hemlocklooper severely defoliated western hemlock atJervis Inlet in the Vancouver Region, the firstpopulation increase since 1969.

After 2 successive years of decline, larch case-bearer populations were generally endemic inwestern larch in southeastern British Columbia.Isolated pockets of moderate or lightly defoliatedmature larch occurred between Montrose andAnarchist Mountain, in the West Kootenay, andbetween Koocanusa Lake and Creston in theEast Kootenay. More than 330 European para-sites were released near Castlegar in the continu-ing biological control program initiated in 1966.Casebearer populations extended slightly beyondknown distribution limits, based on limited trap-ping of male moths in sticky traps. Increasednumbers of larch sawfly in the northern part ofthe Prince Rupert Region moderately defoliatednumerous small groups of tamarack north ofDease Lake and in the Yukon. Colonies severelydefoliated a single non-native larch in Terrace,the first record of the defoliator south of DeaseLake. Discoloration of western larch by needlediseases was conspicuous for the second consecu-tive year in the western part of the Nelson andKamloops regions and to a lesser extent in thesoutheast. Very low numbers of larch budmothlarvae, but no visible feeding damage, were evi-dent in widely separated western larch stands be-tween Castlegar and Anarchist Mountain, but

not elsewhere in stands defoliated by budmothfrom 1983 to 1985.

New infestations of black army cutworm severe-ly defoliated conifer seedlings and herbaceousground cover and delayed planting programs in2-year- old burns in the East Kootenay and in theKamloops Region. Significant population de-clines occurred in previously infested areas in thePrince Rupert, Prince George and Cariboo re-gions. Rhizina root disease was common but notyet damaging in several burned cutblocks in thePrince Rupert Region. A variegated cutwormfound in high numbers in a newly planted site inthe Cariboo Region in 1986 failed to survive thewinter.

Cone and seed pests were at the highest levels inrecent years. A Douglas-fir coneworm destroyedup to 85% of the cones at 34 sites in four forest re-gions and very lightly defoliated new shoots ofDouglas-fir in two natural stands near WilliamsLake. A previously undescribed gall midge in-fested yellow cedar buds and cones in three seedorchards on Vancouver Island. High numbers ofwestern spruce budworm larvae in an interiorseed orchard were reduced by applications ofSevin and Bacillus thuringiensis.

Pests of deciduous forest trees were common forthe second consecutive year. Defoliation of treesand shrubs by forest tent caterpillar was moresevere and widespread in parts of the Cariboo,Kamloops, Nelson, and Prince George regionsthan in 1986 but declined in the Peace Riverarea. Western tent caterpillar colonies in south-western British Columbia declined due to in-creased virus infection, but again increased inthe Okanagan Valley. Effective monitoring withpheromone-baited sticky traps, egg searches, andperiodic control programs have prevented estab-lishment of gypsy moth in British Columbiasince it was first detected in Vancouver in 1974.However, in the cooperative surveys, about 221male moths were trapped in 74 traps in six areas,up from 24 in 19 traps. Fluctuating satin mothpopulations in the Kamloops Region severelydefoliated a cottonwood stand at Stump Lakesouth of Kamloops but declined elsewhere in theregion. Mixed deciduous stands in the NorthThompson River Valley were defoliated by west-ern winter moth for a second year, while standsin adjacent parts of the Cariboo Region weredefoliated for the first time in 10 years; popula-

10

tions increased in the Vancouver Region. Wintermoth populations in Garry oak and maple onsouthern Vancouver Island were at very lowlevels for the third consecutive year, due in partto increased parasitism by introduced parasites.Poplar leaf and shoot blight of aspen was morewidespread in the Cariboo, Nelson, and PrinceGeorge regions. Discoloration of scatteredpatches of white birch by a birch leaf skeletoni-zer was widespread in the northern part of theEast Kootenay in some areas for the thirteenth

consecutive year. Increased mortality of willowby poplar and willow borer was widespread inthe Cariboo Region and around Prince George,where until recently it has not been verycommon.

As well, 56 insects and diseases on 44 hosts weredocumented in British Columbia and the YukonTerritory either for the first time, or on newhosts, or beyond previously known distributionlimits.

Pine Pests

Mountain pine beetleDendroctonus ponderosae

The area and volume of lodgepole pine and somewhite pine killed by mountain pine beetle de-clined overall by about 30% to the lowest level in7 years (Figure 1). However, more than 8900 in-festations are still active on more than 66 470 ha(Table 1) from the international border south ofCranbrook to north of Terrace (Map 1). This isalmost double the area burned by forest fires inBritish Columbia in 1985 and represents about10% of the annual lodgepole pine harvested.Also, lodgepole pine killed by the beetle before1985 and which is now unsalvageable coversmore than 1.86 million ha and 75 000 ha in theCariboo and Kamloops regions, respectively, and575 ha in the Prince George Region.

Declines due to host depletion occurred in thewestern part of Kamloops Region (down 60% to19 000 ha) and in the Homathko River Valley inthe Vancouver Region (down 65% to 1470 ha).Infestations declined 18% in the Nelson Region,but remained active over 23 100 ha mainly southof Cranbrook, near Invermere, and in the Boun-dary District. The area of pine killed by the beetleincreased in three regions. In the CaribooRegion, where in late 1984 and early 1985 mostpopulations were killed by below-normal tem-peratures, a new infestation developed over 500ha near Chilko Lake. In the Prince RupertRegion, the increase was 25% to 18 600 ha, andin the Prince George Region there was an in-

crease of nearly threefold to 4300 ha, mostlynorthwest of Fort St. James.

Overwintering brood mortality assessed in 52major infestations in six forest regions in early1987 was less than 10%. Regional R values, theratio of overwintering progeny to parent beetles,ranged from 0 to 20; most were greater than 4.1,the threshold indicating static to increasing popu-lations. In the Kamloops Region, R averaged7.8: the lowest values occurred west of Lillooet.

500

400

00 300004

200

100

1973 75 77 79 81 83 85 87YEAR

Figure 1. Total area with mountain pine beetle-killedtrees by year in British Columbia.

Areas where recent treemortality was detectedduring aerial surveys.

Canadian Forestry Service / Forest Insect and Disease Survey

1■•

Infestations Area(ha)

Trees killeda

Stands cruisedb

No. Vol. No. Avg. yrs.(000) (000 m 3 ) infested

Damage categoryc

HC R GP of trees

ForestRegion

12

Table 1. Number, area and incidence of new and old attack of mountain pine and engraver beetle byforest region, based on recently killed trees recorded by aerial and ground surveys in BritishColumbia in 1987

Caribood

Kamloops

Nelson

Prince George

Prince Rupert

Vancouver

7 250 3900 — — 8 — 58 — 38 4 —e

1 515 19 000 1 849 852 11 4 72 6 8 11 3

4 367 23 100 1 222 444 13 5 68 13 5 10 4

810 4 300 160 132 2 5 43 34 14 3 6

2 073 18 600f 2 521

1 495 12 7 49 33 12 4 2

101 1 470 55 39 4 6 43 12 19 17 9

Total

8 866 66 470 5 807 2 962 42 55 20 12 9 4

a Trees attacked in 1986, discolored in 1987b Some stands located in younger infestations may not represent average condition.c H = Healthy; C = Current, attached in 1987; R = Red, attacked in 1986; G = Grey, attacked in or before 1985;

P = Partial, or strip attack.d Estimates include data from the British Columbia Forest Service and includes mostly pine killed by pine engraver

beetle which are not included in the total.e Pine engraver beetle only; mountain pine beetle was not found in stands cruised.f Estimates include data from the British Columbia Forest Service.

In the Nelson Region, the average R value was9.4. In the eastern part of the Prince RupertRegion R values averaged 7.9, and they averaged4.1 in western areas. The highest average Rvalues (16.0) were northwest of Fort St. James,near Elliot and Trembleur lakes. Populationsnear Pemberton in the Vancouver Regionremain static or are in decline (average R was2.9) due to declining availability of suitable hostmaterial.

A mild 1986-87 winter and a hot, dry 1987summer, along with increased populations re-sulted in an increased number of new attacks inmature lodgepole pine. New attacks averaged20% in 42 stands in five forest regions, up from11% in 1986. Current attacks were higher in allregions; the highest were in the Prince Georgeand Prince Rupert regions at 34% and 33%, re-

spectively. Other increases occurred in the Kam-loops Region (average 6%, range 0 to 27%) par-ticularly east of Kelowna, the Nelson Region(average 13%, range 0 to 64%) in which the high-est increase was Kootenay National Park, andnear Pemberton in the Vancouver Region(12%). Most stands surveyed were in or adjacentto infestations that have been active for at least 3years, and some that have been active for up to14 years.

The area of mature pine killed by the beetle in1987 in the Kamloops Region contained about1.8 million trees (852 000 m 3) over the smallestarea affected since 1979. Additionally, pine overmore than 75 000 ha killed by earlier attacksremain. The decline, largely due to host deple-tion, occurred mainly in the Lillooet TimberSupply Area (TSA) where most mature suscepti-

13

ble lodgepole pine has been killed since 1972when the outbreak first developed. However,active infestations continue in the OkanaganTSA east of Kelowna, in Mission, Belgo, andDaves creeks and west of the Okanagan Valley inTrout, Hayes, and Short creeks. Groups of 5 to10 beetle-killed pine in the Merritt TSA are lessnumerous this year and are often associated withan intensive pheromone-baiting program by theBritish Columbia Forest Service. Pockets of re-cently killed pine were widely distributed south-west of Princeton and spot infestations southwestof Keremeos follow host depletion and someharvesting.

Pine mortality in the Cariboo Region remainedat the lowest levels since 1972; however, a newinfestation over about 500 ha was recorded bythe British Columbia Forest Service nearFranklyn Arm on remote Chilko Lake near theCoast Mountain Range. Pine mortality is expect-ed to remain generally at low levels throughoutthe region in 1988. Cruises in eight stands adja-cent to beetle-killed mature pine southwest ofRiske Creek found 38% of the stems attacked byengraver beetles, Ips pini, but no new mountainpine beetle attacks were found. An additional7250 pockets containing a total of 3400 ha of pinewhich were recently killed by Ips pini weremapped by the British Columbia Forest Servicein the western part of the region.

Mountain pine beetle infestations in the NelsonRegion (including those in national parks) de-clined 18% to 23 100 ha containing 1.2 milliontrees (440 000 m e ). Although infestations alongthe British Columbia-Alberta border continuedto decline, those in the Boundary, Cranbrook,and Invermere TSAs and in Kootenay NationalPark increased for the second consecutive year to4367 infestations. New attacks in the region in-creased slightly to an average of 13% in 13 standsindicating continued but varied amounts of treemortality in 1988 with the highest at RedstreakCreek (64%) in Kootenay National Park, andnear Steamboat Mountain (25%) west of Inver-mere. New attacks in the Boundary Districtranged from 2 to 17% (average 9%); the highestlevel of new attacks occurred near Eholt.

The area of lodgepole pine killed by the beetle inthe Prince Rupert Region increased, for thesecond consecutive year, to 18 600 ha which con-tained 2.5 million trees (1.5 million m e). This

major increase occurred throughout previouslyinfested areas, mainly the Kispiox, Hazelton,and Kitwanga areas, resulting in part from in-creased populations and in part from varied aerialmapping standards. Increased tree mortality isagain forecast; current attack is forecast to in-crease 33% overall (range 11 to 68%).

Infestations expanded nearly threefold in thePrince George Region to 4300 ha (160 000 trees;132 000 m e ), mostly northwest of Fort St. James.More than 220 infestations occurred from theTarnezell Lake area to south of Takla Landing.Pine beetle control operations in Mt. RobsonProvincial Park reduced the number of beetle-killed pine to 21 trees from 259 in 1985 and 26 in1986. Host depletion and harvesting in theCanoe Arm area south of Valemount further re-duced the number of beetle-killed white andlodgepole pine to 520 trees over 220 ha. Currentattack in two representative stands northwest ofFort St. James averaged 34%, indicate continuingpopulations in 1988. Southwest of PrinceGeorge, declining mountain pine beetle popula-tions were found in one stand and only high num-bers of engraver beetles were found in twoothers. An estimated 570 ha in the Sustut Riverdrainage contained mature pine killed by thebeetle in 1985 and earlier.

The total area containing recently killed pine inthe Vancouver Region declined to 1470 ha and55 000 trees (39 000 m 3 ), and the number of in-festations declined 43%. The decline, due to hostdepletion, was mostly in the Homathko RiverValley, and a lesser decline occurred east ofPemberton.

Secondary beetles, mainly engraver beetles, Ipspini, and to a lesser degree Dendroctonus murraya-nae and Trypodendron spp., attacked and killedpredisposed mature pine adjacent to recently har-vested stands particularly in parts of the Cariboo,Nelson, Prince George, and Prince Rupert re-gions. Pine engraver beetle killed about 38%(range 0 to 46%) of the mature lodgepole pine ineight stands in the Cariboo Region west of theFraser River in the Big, Churn, and Gaspardcreek drainages. Tree mortality resulting from at-tacks in May and July was evident within 15 m ofcutblock boundaries. Slash accumulation and hotdry weather which prevented slash disposal werethe major factors in increased beetle populations.

14

Pinewood nematodeBursaphelenchus xylophilus

Two forms of pinewood nematode were found in1987 in small numbers in four species of pre-viously damaged or predisposed conifers at 12 lo-cations in five regions and in one adult woodbor-er. Based on about 500 trees and 500 potentialvectors sampled since 1983, the nematode is nota conspicuous or damaging forest problem inBritish Columbia and the Yukon.

Based on preliminary identifications, the m formof Bursaphelenchus xylophilus was extracted fromrecently killed lodgepole pine near Creston,Marysville, Vanderhoof, and Prince George,from western white pine near D'Arcy in the Van-couver Region, from Scots pine near Smithers,for the second consecutive year from a deadlodgepole pine near Houston, and from an adultMonochamus maculosus from Wasa Lake in theNelson Region. The r form was recovered fromlodgepole pine near Boston Bar, Tranquille, andCassiar and in a Douglas-fir near Skookumchuckin the Nelson Region. Both forms were in alodgepole pine near Brisco in the East Kootenay.Of the 158 trees sampled in 1987, 61 had nema-todes but only the 11 noted above contained B.xylophilus.

Collections of 439 adult woodborers, mostlyfrom log decks, were extracted for nematodes.These collections included 17 species of ceramby-cids, eight species of buprestids, and five speciesof siricids. The most common woodborer exam-ined was Monochamus scutellatus (246), of which12% contained various nematodes. Otherwoodborers with nematodes associated includedM. maculosus (18%) , Buprestis rusticorum (16%)and B. nuttallii (23%). Less frequently collectedwere M. notatus, Xylotrechus undulatus, andDicera tenebrosa. In most cases the nematodes ex-tracted from adult woodborers were free-livingbacterial feeders in the Tylenchidae or Rhabdidaeand occasionally Aphelenchidae. Only two M.maculosus contained Bursaphelenchus; one fromnear Wasa Lake in the Nelson Region had B. xy-lophilus m form and a sample near Kamloops hada Bursaphelenchus sp. for which identification ispending.

Baited barrier and sticky traps placed adjacent towood chip piles at pulp mills at Crofton andPrince George and near sawmills at Williams

Lake and the Upper Fraser Valley attractedmainly leaf beetles, Altica tombacina, and weevilsof herbaceous vegetation and only one woodbor-er. Lindgren traps at sawmills near Smithers at-tracted small numbers of adult buprestidwoodborers.

Pine needle sheathminerZelleria haimbachi

High numbers of the sheathminer infested andseverely defoliated new shoots of lodgepole pineover more than 650 ha in 15 separate infestationsin the Kamloops, Nelson, and Vancouver re-gions, some of which were attacked for the thirdconsecutive year.

Most new shoots of mainly immature pine wereseverely defoliated over about 300 ha nearSalmon Arm for the third consecutive year. Pinestands from Birch Island to McMurphy in theNorth Thompson River Valley were moderatelydefoliated for a second year. Stands in this areawere severely defoliated by the sheathminer in1979 and 1980. Individual immature lodgepolepine near Gold Bridge were lightly discolored, aswere up to half the shoots of mixed-age pinealong Chase Creek.

New shoots of regeneration lodgepole pine be-tween Cranbrook and Yahk were very lightlydefoliated, in contrast to the severe defoliationduring 1986, the first year of defoliation. West ofGrand Forks, semimature lodgepole pine in fivepatches totalling 225 ha were severely defoliatedfor the first time in recent years. Additionally,roadside trees between Grand Forks and Green-wood, and for 20 km along the Kettle RiverValley road and along State Creek, were lightlydefoliated. Near Kaslo, pine over 3 ha were verylightly defoliated for the second consecutive year.

Defoliation of pine regeneration in the Vancouv-er Region was light to moderate in six areas over150 ha, including stands on the east side of Lil-looet Lake defoliated for a second consecutiveyear. New areas of defoliation occurred nearPemberton and Keefers, and on the west side ofHarrison Lake where about a third of all new pineshoots were defoliated in two areas of 20 and 55ha.

Limited assessments of parasites and overwinter-

15

ing populations were insufficient to allow anaccurate prediction for 1988.

A needle miner, Coleotechnites sp., commonly as-sociated with Z. haimbachii, defoliated up to 70%of the new foliage on the tops of groups of 10 to20 lodgepole pine near Ootsa Lake in the PrinceRupert Region.

Pine needle diseasesLophodermella concolor

Dothistroma pintElytroderma deformans

Native needle diseases were common inlodgepole pine stands in parts of the Nelson,Prince George, and Kamloops regions following2 successive years of decline, and in the southernpart of the Yukon Territory. Systemic infectionsin ponderosa pine were high throughout most ofthe host range, particularly in the KamloopsRegion, similar to the last 4 years.

Infection by Lophodermella concolor increasedgenerally in the East Kootenay part of the NelsonRegion. An average of 30% of the 1-year-old nee-dles on all the regeneration lodgepole pine over 5ha in Redding Creek near Kimberley were infect-ed and up to 50% of the needles in adjacent over-story pine were lost prematurely due to the previ-ous year's infections. Severely infected lodgepolepine were also common in Matthew Creek, andlightly infected stands were common elsewherethroughout the Cranbrook District. North ofWatson Lake, Yukon Territory, 25% of the olderfoliage on lodgepole pine in a natural stand weremoderately infected, but less than 5% of the pinewere infected in a forest reserve at Takhini nearWhitehorse.

Infection of 1-year-old white pine needles in along-term damage assessment plot at SummitLake near New Denver in the Nelson Regionaveraged 80% in the lower third of the crown and10% of the mid crown, up from generally light in-fection in 1986. Consecutive years of infectionhave resulted in premature loss of about 70% ofthe needles on all plot trees.

A third of the 1-year-old needles on most regen-eration lodgepole pine in pockets up to 50 hanear Roche and Paska lakes west of Little Fort inthe Kamloops Region were infected by D. pint;this was more severe than in 1986.

Needle discoloration and brooms caused by E.deformans infection were common in most interi-or ponderosa pine stands, particularly in theKamloops Region. Up to 75% of the crowns ofthe mature pine were infected in many stands upto 100 ha.

A conifer weevilMagdalis sp.

Moderate to severe defoliation of lodgepole pineby this weevil was recorded for the first time inBritish Columbia in the Cariboo Region. Newshoots in two recently spaced young stands nearMoffat Lake south of Horsefly, in immature pinenear Mt. Alex west of Dog Creek, and south ofWilliams Lake near Spring Brook were defoliatedby adult weevils. Weevil populations, which usu-ally infest slash, increased in part due to highoverwintering survival during the mild 1986-87winter, the hot dry summer, and the increasedavailability of slash arising from thinning and har-vesting of mature pine killed by mountain pinebeetle.

16

Douglas-fir Pests

Western spruce budwormChoristoneura occidentalis

The area of mature and immature interiorDouglas-fir defoliated by the budworm in 1987doubled to more than 834 000 ha in more than1060 separate infestations, mostly in the Kam-loops Forest Region but including small areas inthree adjacent regions (Map 2). This is the largestarea of Douglas-fir defoliated by this budworm inBritish Columbia since surveys started 50 yearsago. Most of the defoliated Douglas-fir standswere in the Kamloops Region (98%); less exten-sive defoliation occurred in the Cariboo, Nelson,and Vancouver regions. Overall, 76% of the defo-liated areas sustained light defoliation, 22% sus-tained moderate defoliation, and 2% sustainedsevere defoliation. The most significant areas ofexpansion were in the Kamloops Region at thenorthern limits of the host range near Clearwaterand Wells Gray Provincial Park in the NorthThompson River Valley and east of Clearwater inthe Adams Lake drainage. Smaller expansionsoccurred around Vernon and west of Penticton inthe Okanagan Valley. Areas of Douglas-fir defo-liated in 1986 but not this year totalled more than76 000 ha; most of the areas of decline (59 000ha) occurred in the Savona, Ashcroft, and Clin-ton areas. Contributing factors included popula-tion starvation, migration, and parasitism.

The area of Douglas-fir defoliated by the bud-worm in the eastern part of the Cariboo Regionincreased significantly to 9000 ha in 37 separateareas of mainly light defoliation near Quesnel,Horsefly, Canim, and Mahood lakes. Major ex-pansion occurred near Mahood Falls and BowersLake where defoliation occurred for the first timein 1986 over 180 ha. In the southern part of theregion, Douglas-fir over 550 ha on Big Bar Moun-tain west of Clinton were moderately defoliatedagain after a population decline in 1986.

Budworm populations again increased nearD'Arcy in the Vancouver Region and lightly tomoderately defoliated Douglas-fir over 2850 hain 13 areas in the Blackwater, Haylmore, andGates creek drainages, up from 1250 ha in 1986.

Douglas-fir east of Anarchist Mountain in theNelson Region were lightly defoliated over 1000ha, down from 3700 ha in 1986. Undeterminednatural factors affected overwintering early-instarlarvae.

The last 6 years of budworm infestations werecompared by computer overlays to aid tree condi-tion assessments. Of the total area infested todate, most (60%) has been defoliated 1 year,27% has been defoliated for 2 consecutive years,1 0 % for 3 consecutive years, and 2% for 4 years.Less than 1% of the total area had been defoliatedfor 5 or 6 years.

Based on egg masses per 10 m 2 of foliage from 10trees at each of 67 locations, defoliation in 1988is forecast to be severe in 6 1 % of stands in theKamloops and adjacent regions, moderate in27%, and light in the remainder (Map 3). Most ofthe severe defoliation will be in the KamloopsRegion in the North Thompson, Adams River,and Okanagan Valley drainages, with smallerareas in the eastern part of the Cariboo Regionand east of Anarchist Mountain in the NelsonRegion. Light to severe defoliation is forecast forthe D'Arcy area in the Vancouver Region. Instands defoliated in both 1986 and 1987, defolia-tion is again predicted, but there was a 31% de-crease in the number of egg masses. Also, theforecasts may be slightly conservative.

Comparisons of predicted and actual defoliation,based on 1986 egg samples and 1987 defoliationat 36 locations in the Kamloops Region, showedagreement at 48% of the sites, less defoliationthan predicted at 40% of the sites, and moresevere defoliation than predicted in only 12% ofthe stands.

Parasitism of early- and late-instar larvae oc-curred at all 28 sites sampled, mostly in the Kam-loops Region, and averaged 18% (range 6 to79%), up 10% from 1986, but too low to effec-tively reduce populations. There was no evidenceof viral or fungal infections.

Larvae and male adult populations were moni-tored at 14 locations in four regions to improve

0 40 80 km

1

Map 2

Western spruce budworm

1987

Areas where currentdefoliation was detectedduring aerial surveys.

I.

CANADIAN FORESTRY SERVICE/FOREST INSECT AND DISEASE SURVEY

18

0 40 80 kmI I I

0W

Map 3

Western spruce budworm

1988

Predicted defoliation.

Q light

Q moderate

• severe

99• 0 •0 9 ••

0 • • w •.90

CANADIAN FORESTRY SERVICE/FOREST INSECT AND DISEASE SURVEY

19

and calibrate methods to detect western sprucebudworm in Douglas-fir forests. Further data arenecessary before numbers can be correlated withpopulation changes and damage.

Mortality of understory trees, top-kill, andgrowth loss are variable but evident in standsmoderately or severely defoliated for more than4 successive years, mostly in the KamloopsRegion. Near Ashcroft, mortality of immatureand some mature Douglas-fir, a result of about 6consecutive years of severe defoliation, wasmapped over 540 ha. In 65 plots of open-growingregeneration, mortality averaged 3% (range 0 to33%) and much of the remainder are severelydefoliated. Greater damage exists where regener-ation is over-topped by older trees.

An aerial spray trial, conducted by the BritishColumbia Forest Service and the British Colum-bia Ministry of Environment and Parks, appliedBacillus thuringiensis over about 200 ha ofbudworm-infested Douglas-fir at Paul Lake Pro-vincial Park near Kamloops and over 10 nearbyblocks of immmature Douglas-fir totalling 700ha.

Douglas-fir tussock mothOrgyia pseudotsugata

Increased numbers of male adults caught inpheromone-baited sticky traps for the secondconsecutive year reflect a possible outbreak inDouglas-fir stands in 1988-89 in parts of theKamloops and Nelson regions previously infestedby the tussock moth. Larvae were not found atany permanent monitoring sites or in other sus-ceptible stands. A total of 387 adult males weretrapped in 45 of 120 traps at 12 of 20 sites in tworegions, up from 75 moths in 25 traps in 1986.

Populations are forecast to increase again in 1988based on the increased numbers of male adults.Larval detection and adult trap monitoring pro-grams will be intensified, particularly nearCherry Creek and Winfield where the averagenumber of moths per trap increased to 24 and 23,respectively. Average catches of 8 to 10 mothsper trap indicate a potential outbreak in 2 years.The last outbreak, which lasted 3 years and col-lapsed in 1984, covered 23 500 ha, mainly in theKamloops Region.

Growth loss in Douglas-fir stands defoliated in

1981 and sprayed with Bacillus thuringiensis in1982 is still being evaluated by the Damage Ap-praisal group of the CFS. Cumulative mortalityof Douglas-fir defoliated from 1981 to 1983 bytussock moth in the Kamloops Region averaged51% of the trees (49% by volume) and 11% ofthe survivors were top-killed. Assessments in 45plots showed that 56% of the dead trees died afteronly 1 year of severe defoliation; the remainderdied after 2 years. There was no significant rela-tionship between tree mortality and maturity.Top-kill was most severe on larger diameter treesand immature trees sustained very little top-kill.

Douglas-fir beetleDendroctonus pseudotsugae

Widely scattered pockets totalling 400 ha contain-ing mainly mature predisposed Douglas-fir in 38areas were killed by Douglas-fir beetle in theCariboo Region and to a lesser extent in the Van-couver, Prince George, and Nelson regions.

Beetle-killed Douglas-fir in the Cariboo Regionwere scattered in five pockets over 295 ha mostlyon Big Bar Mountain west of Clinton. Additional-ly, beetle-killed Douglas-fir were mapped by theBritish Columbia Forest Service in numerouspockets totalling 300 ha, mostly north and westof Williams Lake. Small groups of one to threemature beetle-killed trees, most weakened byovermaturity and root disease, occurred in pock-ets in the Prince George and Vancouver regions.The Douglas-fir beetle is at generally low endem-ic levels and little change is forecast in 1988.

A Douglas-fir conewormDioryctria pseudotsugella

New shoots of interior Douglas-fir near WilliamsLake and in the Thompson River drainage weredefoliated by increased numbers of conewormlarvae. Most of the new tips of overmatureDouglas-fir were severely defoliated along thenorth shore of Williams Lake between Asahaland Mission creeks and increased populationsvery lightly defoliated Douglas-fir on both sidesof Highway 20 east of the Fraser River. In theKamloops Region, increased populations, oftenin association with high numbers of westernspruce budworm, Choristoneura occidentalis, con-tributed to the overall defoliation, particularly inthe Thompson River drainages and to a lesserdegree in the Okanagan Valley.

20

Spruce Pests

Spruce beetleDendroctonus rufipennis

The area and volume of mature white and Engel-mann spruce killed by spruce beetle in BritishColumbia declined for the fifth consecutive yearto 63 infestations over 3000 ha, from 298 over3800 ha in 1986. Although this insect was activein all six forest regions, all but 80 ha of the recentbeetle-killed stands were in higher-elevationstands south of Gold Bridge and west of Prince-ton in the Kamloops Region. The continuing de-cline was due to salvage of infested trees, im-proved sanitation, host depletion, and low tern-peratures in 1984 and 1985.

The area of recently killed mature spruce in theKamloops Region increased for the fourth con-secutive year to 2900 ha. Most of this increasewas in the Anderson Lake and Gold Bridge areaswhere 11 remote, high-elevation infestationscovered 2050 ha, up from 1360 ha in 1986. Westof Princeton in the Upper Tulameen River drain-age, infestations increased slightly to 875 ha in22 pockets.

The area and number of recently killed maturespruce in the Prince George Region declined forthe sixth consecutive year to endemic levels inscattered pockets over 17 ha, mostly in the Mc-Gregor and Bowron river drainages.

Tree mortality declined to endemic levels in thePrince Rupert Region following years of host de-pletion from beetle attacks and harvesting; how-ever, pockets of 25 spruce in the upper KispioxRiver drainage that were attacked in 1986 containhigh numbers of broods which pose a threat toadjacent stands when they emerge in 1988. Cur-rent attacks are restricted to single trees mostlyin the northeastern part of the region and usuallythose predisposed by disease or windthrow.

Twenty mature spruce, mostly windthrown, inpockets along the Haines Road north of theAlaska border were very lightly strip-attacked.Trees in the area have been predisposed by theeffects of road construction since 1983. However,control programs have effectively reduced the

potential for continuing tree mortality.

Little change is expected in the status of thebeetle in 1988. However, endemic populations inscattered windthrow, right-of-way logs, and buttsof standing trees in most regions have the poten-tial to threaten nearby susceptible mature stands.

Spruce aphidElatobium abietinum

The aphid population on the Queen Charlotte Is-lands increased following 2 years of low popula-tions and severely defoliated older needles ofSitka spruce in coastal areas of Graham Islandand northern and eastern Moresby Island. About70% of the old foliage was lost in a 1984 spruceplantation near the north end of Moresby Island.However, in a 1980 plantation at Miller Creek onGraham Island, only 12% of the trees wereseverely defoliated, 36% were moderately defo-liated, and the rest had light defoliation. In anearby study plot established in 1982, 60% of themature spruce are now dead after periodic severedefoliation. Very light feeding on small groups ofspruce occurred at isolated locations north andsouth of Prince Rupert. On Vancouver Islandand on the lower mainland coast in the Vancouv-er Region, increased populations moderatelydefoliated Sitka spruce and severely defoliatedornamental spruce from Port Hardy to Hope.

Overwintering populations are significantly in-fluenced by temperatures and often increase fol-lowing mild conditions such as those which oc-curred in 1987.

Spruce weevilPissodes strobi

Weevil attacks in 9- to 14-year-old Sitka spruceat seven sites in the Kitimat River Valley in thePrince Rupert Region killed 2 to 63% (average29%) of the terminals. The highest incidence ofmortality was in three stands adjacent to the riverwhere an average of 58% (range 50 to 63%) ofthe leaders were killed. In the remaining stands,

LI

mortality ranged from 2 to 27%, declining withdistance and elevation from the river. Elsewherein the western part of the region, terminal leadermortality at 10 sites averaged 38% (range 0 to45%). Leader mortality is very low (average 8%,range 0 to 26%) in five stands in the western partof the Skeena River Valley and 6% (range 2 to12%) in four stands in the northern part of theNass River Valley where extensive planting ofSitka spruce is planned.

Spruce bud insects

New growth of young Sitka spruce in the westernpart of the Prince Rupert Region was damagedfor a second year. Spruce budmoths, particularlyZeiraphera canadensis, damaged an average of72% of the new buds of 6- to 14-year-old trees in

13 plantations in the Kitimat, Copper, andSkeena river drainages, similar to 1986. A sprucegall adelgid, Pineus sp., and pineleaf chermid, P.pinifoliae, lightly infested new shoots on 12 to56% (average 46%) of the Sitka spruce in 11 plan-tations, similar to 1986.

Northern spruce engraver beetleIps perturbatus

Fewer than 50 upper crowns of mature sprucewere killed by 1987 engraver beetle attacks in theeastern part of the Prince George Region. Mostwere widely scattered throughout the McGregorand Parsnip river drainages; no current damagewas seen in the Torpy and Bowron river valleys.The decline from 4000 tops killed in 1985 wasdue to undetermined causes.

True Fir Pests

BudwormsChoristoneura spp.

Defoliation of alpine fir and spruce forests in fourforest regions by eastern spruce budworm and2-year cycle budworms was mostly light over59,400 ha and 59 750 ha, respectively (Map 4).

Defoliation of current foliage of alpine fir andwhite spruce by eastern spruce budworm, Choris-toneura fumiferana, was light to moderate over59 400 ha along the Fort Nelson and Liard rivervalleys in the Prince George Region and into theNorthwest and Yukon territories. Light defolia-tion occurred for the second consecutive year be-tween Coal and Smith rivers, near Liard HotSprings and Kledo Creek west of Fort Nelson.The infested area mapped by aerial survey de-clined from nearly 95 000 ha in 1986, which wasthe first year of expansion since the mid 1970s.The apparent decrease may have been due, inpart, to poor weather which delayed aerial detec-tion surveys by a month and reduced aerially visi-ble evidence of light budworm feeding. Adultmale moths were caught in pheromone-baited

non-sticky traps near Fort Nelson and Liard HotSprings. The numbers of male moths (average43, range 0 to 102) indicate budworm populationswill be variable but will continue in the FortNelson area in 1988.

Most of the alpine fir-spruce forests defoliated byearly-instar, 2-year cycle budworm, C. biennis,were in the east and southeastern parts of thePrince George Region. Light defoliation in 36 in-festations covered 20 000 ha, up 22% from 1986and up from 580 ha defoliated by similar early-instar larvae in 1985. Most defoliated stands atEverett Creek, near Tumuch and Stoney lakes bythe Cariboo regional border, had been defoliatedby mature larvae in 1986. New infestations devel-oped over 4000 ha in the Morkhill Riverdrainage.

In the northeastern part of the adjacent CaribooRegion, mostly around Quesnel Lake, 78 alpinefir-spruce forests over 11 250 ha were lightlydefoliated.

Sixty-nine separate infestations in the upper

Map 4

1. Eastern spruce budworm2. Two-year cycle

budworms3. Western hemlock looper4. Larch sawfly5. Forest tent caterpillar

1987

Areas where currentdefoliation was detectedduring aerial surveys.

BRITISH COLUMBIA

0 100 200 kmI I

Canadian Forestry Service / Forest Insect and Disease Survey

23

North Thompson River drainage, includingiem-priere Creek, covered 17 000 ha, most of whichhad been also lightly defoliated by mature larvaein 1986.

Although high numbers were forecast from 1986egg samples, significant feeding damage was notexpected to occur until 1988 when larvaemature. The mild 1986-87 winter and warm 1987spring probably increased larval survival, budmining, and defoliation intensity.

The high numbers of eastern budworm and2-year cycle larvae in defoliated fir-spruce standsin the Prince George, Cariboo, and Kamloops re-gions indicate continuing populations and poten-tially widespread defoliation in 1988.

Immature "off-year" 2-year cycle budwormlarvae defoliated 60 pockets of high-elevationalpine fir-spruce over 11 500 ha in the NelsonRegion, mostly in the East Kootenay. As predict-ed from 1986 egg samples, defoliation in theupper St. Mary River drainage west of Kimberley,including Dewar, Redding, and Baker creeks,was severe over 475 ha, moderate in 13 separateinfestations over 3500 ha, and light over 5000 ha.In Bugaboo Creek west of Invermere, newshoots were lightly defoliated over 700 ha. In theWest Kootenay, five areas were lightly defoliatedover 1650 ha in Fosthall and Cusson creeks,where infestations first developed in the early1980s. Along Airy Creek west of Slocan, fourpockets of fir-spruce were lightly defoliated forthe first time. Based on egg samples in threestands, young larvae are forecast to be numerousin alpine fir and spruce buds in 1988, but are notexpected to cause significant defoliation untilthey mature in 1989.

To improve and calibrate methods to detect bud-worm in fir-spruce forests, larvae and male adultpopulations were monitored at 16 locations inthree regions. Although up to 200 larvae and 300males were collected per location, further dataare necessary before numbers can be correlatedwith population changes and damage.

Balsam woolly adelgidAdelges piceae

For the first time the adelgid was discovered sub-stantially beyond the 1976 regulation and infesta-

tion zones (Map 5). Mature amabilis fir wereseverely infested and about 30% were killed in a150-ha mixed conifer stand on West ThurlowIsland in Johnstone Strait about 80 km north ofthe zone's boundary. Mortality of amabilis firhad occurred over several years.

Limited aerial surveys and ground checks of anadditional 63 amabilis and grand fir stands withinand outside the zones on Vancouver Island, theLower Mainland and along the internationalborder in the Nelson Region found only verylight active populations and only within the qua-rantine zone. These included lightly infestedtwigs on up to 35% of the amabilis fir in threeseed orchards near Victoria and one nearNanaimo. Mortality of mature amabilis fir attri-butable to adelgid attack averaged 15% (range 0to 95%) in or near 10 damage plots established bythe CFS in 1966 and 1970 near Victoria andVancouver.

Changes to quarantine and regulation zones arebeing considered because of the discovery onWest Thurlow Island. Detection and monitoringsurveys will continue in 1988.

Western balsam bark beetleDryocoetes confusus

Mortality of mature high elevation alpine fir wasmapped in more than 320 separate infestationsover 9150 ha in six forest regions. Additionally,70 000 ha in the Bulkley TSA in the PrinceRupert Region contained recently killed maturealpine fir.

Most of the fir killed by the beetle-fungus com-plex in the Prince George Region in 140 infesta-tions covering 6125 ha were in the Morkhill, Mc-Gregor, and Monkman river drainages east ofPrince George and near the northwest arm ofTakla Lake. Lesser damage occurred northwestof Finlay Forks along the Mesilinka River.

In the Cariboo, Kamloops, and Nelson regions,areas containing recent beetle-killed treesmapped by aerial surveys declined to 80 ha, 1750ha, and 775 ha, respectively, in about 140 sepa-rate infestations; in 1986, the corresponding fig-ures were 375 ha, 2250 ha, and 2370 ha in about200 infestations. Additionally, more than 320pockets totalling 1600 ha were mapped in the

■1111111111M

Map 5

Balsam woolly adelgid

1987

• Infestations recorded to date.

Regulation area boundary (1976).

Infestation zone boundary.

VANCOUVER FOREST REGION

0 40 80 km

41 to‘a0 tet

% , • • • lijj%• • • • • •••• 1 • • • • •1 1 ••• ••• 1

• i • \•

si

CANADIAN FORESTRY SERVICE/FOREST INSECT AND DISEASE SURVEY

25

eastern part of the Cariboo Region by the BritishColumbia Forest Service.

In the Vancouver Region, however, infestationsexpanded slightly to 420 ha in 44 pockets contain-

ing an estimated 10 450 trees (11 410 m s). Mostwere in the Mowhokam and Kookipi creek drain-ages; lesser damage occurred near Pembertonand at Alfred Creek on the Sunshine Coast.

Hemlock Pests

Western blackheaded budworm andHemlock sawfly

Acleris gloverana and Neodiprion tsugae

In the third consecutive year of outbreak on theQueen Charlotte Islands, blackheaded budwormand hemlock sawfly larvae defoliated about 220separate mature and immature western hemlockstands over an estimated 14 100 ha (Map 6),about a third of the area affected last year. Addi-tionally, tree mortality following successive yearsof severe defoliation was mapped over 1500 haand in widely scattered pockets totalling 2170 hathroughout defoliated stands. Populations col-lapsed near Kitimat, near Creston in the NelsonRegion, and near McBride in the Prince GeorgeRegion. New blackheaded budworm infestationsdeveloped in hemlock stands in the KamloopsRegion over 1100 ha and in a single 5-ha standnear Holberg on Vancouver Island. In the easternpart of the Prince Rupert Region from theNadine River northwest to near Hazelton mostwhite spruce and alpine fir stands were very light-ly defoliated. Budworm populations in the areahave been common since 1982, but populationlevels have fluctuated and little damage hasresulted.

Defoliation, mostly on Graham Island, totalled14 100 ha of which 19% was severe, 61% wasmoderate, and 20% was light. In most areas, defo-liation was caused primarily by hemlock sawflyfeeding on older foliage and budworm defoliatingthe new foliage. Defoliation of mature westernhemlock in mixed hemlock-cedar stands in theKamloops Region was light in five separate infes-tations in the upper Clearwater River drainage,in Wells Gray Provincial Park, and in the upperAdams River drainage east of Avola. A single5-ha pocket of mature hemlock was very lightly

defoliated near Holberg. This was the first inci-dence of defoliation on Vancouver Island since aprevious outbreak collapsed in 1973.

Defoliation of western hemlock stands on theQueen Charlotte Islands is forecast to decrease in1988; defoliation will be severe at only one loca-tion, moderate at three, trace or light at 24, andseven sites will be free of defoliation (Map 7).Assistance in obtaining samples for egg washingfrom the 35 sites was provided by the BritishColumbia Forest Service and forest industry per-sonnel. Severe defoliation of western hemlock isforecast near Holberg, and light defoliation isforecast in the inaccessible stands in the northernpart of the Kamloops Region. Although defolia-tion is not forecast near Kitimat, new shoots ofwhite spruce and alpine fir at seven locations inthe eastern part of the Prince Rupert Regioncould be lightly or moderately defoliated.

Parasitism of blackheaded budworm larvae fromHonna River on the Queen Charlotte Islandsaveraged 6%, which is too low to reduce popula-tions, and less than an average of 16% in threeareas in 1986.

Numerous hemlock sawfly cocoons on 50-cmhemlock branches at 11 of 26 sites indicatedamaging population levels, mostly on GrahamIsland, in 1988. Mortality of prepupal sawfly aver-aged 54% (range 10 to 88%) at 26 sample sites.Infection by Entomophthora occurred at only onesite while viral infection at all sites averaged l4%and parasitism averaged 38%.

Tree mortality estimated during aerial surveysaveraged 25% (range 1 to 80%) in 77 separate in-festations totalling 3670 ha, mainly on MoresbyIsland. About half of these were in 20- to 100-

Map 6

Western blackheadedbudworm and

hemlock sawfly

1987

Areas where currentdefoliation was detectedduring aerial surveys.

QUEEN CHARLOTTE CITYOr •

SANDSPIT

LOUISE ISLAND

GRAHAM ISLAND

MORESBY ISLAND

LYELL ISLAND

26

Canadian Forestry Service/Forest Insect and Disease Survey

National Park Reserve

MASSET

MASSETI L Predicted defoliation

O noneO trace© lightto moderate• severe

TLELL

GRAHAM ISLAND

Map 7

Western blackheadedbudworm

1988

QUEEN CHARLOTTE CITYSANDSPIT

LOUISE ISLAND

MORESBY ISLAND

TASU LYELL ISLAND

Canadian Forestry Service/Forest Insect and Disease Survey

National Park Reserve

28

year-old stands; the remainder were in olderstands. Evidence in 1987 of refoliation of pre-viously defoliated tops has deferred impact as-sessments at 10 plots established on the QueenCharlotte Islands in 1985 (two on MoresbyIsland and eight on east coastal islands) untilafter the outbreak has collapsed.

Semimature hemlock in plots established in 1975near Port Alice on Vancouver Island followingdefoliation by blackheaded budworm in 1972-74were surveyed this year but showed no evidenceexternally of growth impact such as dead trees,tops, or branches. Volume loss through reducedincrement is being re-evaluated.

Western hemlock looperLambdina fiscellaria lugubrosa

A new hemlock looper infestation developed inmulti-age western hemlock over about 90 ha onthe west side of Jervis Inlet north of Sechelt inthe Vancouver Region (Map 4). Western hem-lock were severely defoliated and so, to a lesserdegree, were western red cedar, broadleaf mapleand other deciduous understory shrubs in fourpatches between Patrick Point and CrabappleCreek on the southwest side of Queens Reach.High numbers of adults in infested stands inSeptember indicate continuing populations inthe area in 1988. High numbers of hemlocklooper but no defoliation were last recorded inthe area in 1969; near Coquitlam Lake standswere defoliated for 5 consecutive years resultingin mortality and harvesting of mature westernhemlock.

Larch Pests

Larch casebearerColeophora laricella

After 2 successive years of decline, casebearerpopulations were generally endemic in westernlarch stands in the Nelson and Kamloops regions.Isolated pockets of moderately defoliated maturelarch occurred, however, in previously infestedstands in the Nelson Region near Castlegar,Montrose and Fruitvale. Lightly discolored pock-ets occurred at Thrums, Rossland, and AnarchistMountain in the West Kootenay and in the EastKootenay between Koocanusa Lake and Crestonwhere populations declined significantly. Defolia-tion at 16 of 26 long-term study sites betweenKoocanusa Lake and Anarchist Mountain aver-aged less than 10% and was restricted largely tothe lower third of the crowns. Trees in the re-maining plots were not defoliated. Populations inthe western part of the host range in the Kam-loops Region were at endemic levels and defolia-tion was not seen from Salmon Arm south toAnarchist Mountain.

Discoloration of western larch by the larch

needle diseases Hypodermella laricis and Merialaricis, combined with casebearer damage, oftencomplicated accurate identifications.

Prepupal parasitism ranged from 3 to 38% (aver-age 18%) at 21 of 25 sample locations and therewere no pupae at one site. A native chalcid, Spilo-chalcis albifrons, and an introduced parasite,Chrysocharis laricinellae, were most commonwhile Agathis pumila occurred only in very lownumbers. As part of a biological control programinitiated by the Forest Insect and Disease Surveyof the CFS in 1966, about 331 of the male andfemale European parasites C. laricinellae and A.pumila were released between mid July andAugust in three casebearer-infested stands nearCastlegar.

Defoliation of western larch is forecast to increaseslightly to generally light with moderate defolia-tion near Castlegar and Rossland and patches ofsevere defoliation east of Vernon. This is basedon overwintering larval population assessmentsat 20 sites in the Nelson and Kamloops regions.

29

A trapping program to monitor the spread ofcasebearer populations beyond known distribu-tion limits indicates a slight expansion of adultpopulations. An average of six adults (range 1 to10) were caught in five traps at each of fourlocations.

Larch sawflyPristiphora erichsonii

Increased sawfly populations lightly or moderate-ly defoliated western larch in the southeasternpart of the Nelson Region and tamarack in thenorthern part of the Prince Rupert Region westof Watson Lake and in southeastern Yukon(Map 4). Populations declined in exotic larchnear Haney in the Vancouver Region.

Populations in western larch between Elko andSparwood lightly or moderately defoliated 11pockets of mixed age stands totalling 600 ha; thisfollowed a population decline in the area in 1985.An additional 100 ha were defoliated at DutchCreek. Defoliation averaged 44% at two locationsin the Elk River valley and 45% at Dutch Creekwest of Fairmont. Between 41 and 90% (average64%) of the overwintering sawfly cocoons at thethree sites were healthy, indicating continuingpopulations in 1988. Populations are also expect-ed to continue north of Elko to Bull River whereincreased numbers of larvae but no visible defoli-ation occurred in 1987.

Numerous small groups of tamarack in the north-ern part of the Prince Rupert Region south of theYukon border, where sawfly larvae have occurredperiodically since 1959, were moderately defoliat-ed by increased sawfly populations. Increasingpopulations but no defoliation of tamarack oc-curred along the Robert Campbell Highway andTungsten Road and west of Watson Lake in theYukon Territory following a decline in 1986.

Several exotic larch in Terrace were severelydefoliated by sawfly, the first record of the defoli-ation in the area; none was found on Siberian,Japanese, and European larch in 25-year-oldplantations in the Kalum Valley near Terrace.Sawfly colonies in native and exotic larch planta-tions in the University of British Columbia Re-search Forest in Haney collapsed after severelydefoliating western larch for 2 consecutive years.

Larch needle diseasesHypodermella laricis

Meria laricis

Discoloration of western larch by needle diseaseswas conspicuous for the second consecutive yearin the western part of the host range in theNelson and Kamloops regions, and to a lesserdegree in the southeast. The area and intensity ofinfection varied, but the infection was generallymore severe and widespread than in 1986.

Infection by both Meria laricis and Hypodermellalaricis was most evident in the West Kootenay be-tween Westbridge and Beaverdell, where singletrees and stands up to 5 ha were moderately toseverely discolored. At Johnstone Creek Provin-cial Park and in the Halfway River Valley about afifth of the crowns of all the western larch in20-ha patches were infected and discolored.Lightly infected smaller patches were commonnorth of Kaslo along Kootenay Lake.

Infection increased slightly in the East Kootenayand severely infected larch stands alongKoocanusa Lake in the Lussier and White riverdrainages and near Moyie Lake. Lightly discol-ored small patches of larch were numerous in theSt. Mary River Valley and were also commonelsewhere throughout the host range, most no-ticeably in the Purcell, Gold, and Cabin creekdrainages.

In the Kamloops Region, areas of western larchinfected by M laricis expanded slightly in theeastern part of the region. Severely infectedstands were most common in 1- to 200-hapatches east of Vernon to Cherryville. Scatteredpockets lightly infected by H. laricis were numer-ous from Naramata to east of Kelowna and eastof Vernon including Silver Star Provincial Park.Pockets of mature larch in mixed conifer standsin the north Okanagan from Glenemma to Falk-land were severely infected and discolored andlarch in pockets of 1 to 5 ha west of Tappen, nearSicamous, and east of Salmon Arm were moder-ately infected and discolored.

Larch budmothZeiraphera improbana

Endemic budmoth populations occurred in partsof the Nelson and Kamloops regions where west-

30

ern larch stands were defoliated from 1983 to1985.

Very small numbers of larvae but no feedingdamage were evident near Castlegar, JohnstoneCreek, and Anarchist Mountain in the WestKootenay, but none was found in previously in-

fested stands west of Castlegar or near Yahk inthe East Kootenay. Low populations persist insmall, higher-elevation pockets of western larchnear Vernon and none was evident in other pre-viously infested stands east of the OkanaganValley.

Multiple Host Pests

Black army cutwormActebia fennica

New infestations of black army cutworm severelydefoliated conifer seedlings and herbaceousground cover and delayed planting programs in 2-year-old burns in the East Kootenay and in theKamloops Region. Significant population de-clines occurred in previously infested areas of thePrince Rupert, Prince George, and Caribooregions.

Spruce and pine seedlings, planted in late 1986,and patches of ground cover over an estimated1000 ha were severely defoliated in parts of the1985 Ram Fire east of Canal Flats in the NelsonRegion. Planting in the nearby Giby Fire wasdelayed until larval feeding, which severely defo-liated patches of ground cover over about 900 ha,was concluded. Small numbers of larvae occurredin the Black Fire in the same general area and atMarl Creek north of Golden. However, neitherlarvae nor feeding damage was observed duringsurveys of other recent burns in Matthew andFindlay creeks in the East Kootenay, nor inburned sites in the West Kootenay at Aaron Hilland Wilson Creek.

About 10% of the newly planted Douglas-firseedlings in a 2-year-old burn in the Fly Hillsnear Salmon Arm in the Kamloops Region weremoderately to severely defoliated by greatly in-creased cutworm larval populations. Most herba-ceous ground cover on ridge tops and west-facingslopes on about 5% of the 80-ha area were totallydefoliated. On a 150-ha site at the upper end ofOtter Creek near Vavenby which was burned in

1984, larvae destroyed half the foliage on 10% ofthe Douglas-fir seedlings. Additionally, allground cover foliage in about six patches over upto 1 ha on west facing slopes and ridge tops wastotally stripped and up to 20 late-instar larvaewere counted in 1000-cm 2 duff samples.

Cutworm larvae were at their lowest levels inrecent years in previously infested areas in theeastern part of the Prince Rupert Region. Fewerthan three larvae per 1000-cm 2 duff sample, noseedling damage, and only minimal feeding onground cover were evident in burned sites atHarold Price and Pinkut creeks, near SmithersLanding and Chapman Lake.

Populations of black army cutworm completelycollapsed in the Prince George Region followingseveral years of high populations which severelydefoliated newly planted conifer seedlings.Recovery of severely defoliated seedlings in addi-tion to seedling mortality is being assessed.There was no evidence of larval feeding wherelarvae had been numerous in 1986 including theBowron River drainage, Haggen Creek, and theMissinka River drainage north of Prince George.

There was little evidence of cutworm larvae inthe Cariboo Region, where populations werecommon but damage was minimal in 1986. Verylow numbers of larvae were seen for the firsttime in a 1986 burn at Victoria Creek east ofQuesnel, but there was no feeding damage to theDouglas-fir and white spruce seedlings or toground cover. Other sites burned in 1986 in thenortheastern part of the region including LittleRiver and Mackay River valleys and Bosk Lake

31

where pheromone-baited sticky traps attracted10 or more male adults in 1986 showed no signsof larvae this year.

Parasitism of cutworm larvae and pupae, respec-tively, averaged 22% and 37% in the PrinceRupert, Prince George, and Cariboo regions in1986. This contributed to the population declinealong with predation by voles and birds and virusinfection. Larval and pupal parasitism in new in-festations in the Nelson Region averaged 2.3%,too low to reduce populations in 1988. However,at Otter Creek near Clearwater in the KamloopsRegion parasitism approached 50%.

Continuing populations are forecast for parts ofthe Nelson and Kamloops regions, but cutwormpopulations should remain low elsewhere. This isbased on 230 sticky and four multipher trapsbaited with experimental pheromones which at-tracted up to 64 male moths per trap at 43 sites infour regions. An additional 93 traps (57 sticky,36 multipher) set out by the British ColumbiaForest Service near Clearwater in the KamloopsRegion attracted up to 45 adults per trap (average11). Cutworms could pose a threat to 1988 plant-ings where slash burning occurred in 1986 inparts of the interior.

Building on earlier work conducted by Dr. RoyShepherd in cooperation with FIDS, a 3-year con-tract to develop a predictive warning system link-ing moth catches in pheromone traps with subse-quent defoliation as well as seedling and vegeta-tion damage was started this year.

Rhizina root disease, Rhizina undulata, was abun-dant in several cutblocks north of Hazelton in thePrince Rupert Region. There was no damage onspruce and pine seedlings planted this year. Thisfire-related disease was first observed affectingconifer seedlings in British Columbia in 1967 andin the Prince Rupert Region in 1968. Damagewas usually prevalent in the first year after theburn, slightly reduced in the second year, andhad usually disappeared in the third year.

As predicted, populations of the variegated cut-worm, Peridroma saucia, which occurred for thefirst time in high numbers in 1986 in the easternpart of the Cariboo Region, were not present onthe site in 1987. Some spruce seedlings andground cover over part of the plantation hadbeen severely defoliated. Overwintering mortali-

ty of pupae was 77%; 64% died during the winter,predation killed 11%, and 2% were parasitized.Pheromone-baited sticky traps at two recentlyburned sites nearby attracted an average of oneand five moths, probably too few to sustain apotentially damaging larval population.

Cone, seed, and seed orchard pests

Cone crops were generally light to occasionallyheavy in interior forests and rare in coastal areas.Cone and seed pests were at the highest levels inrecent years due in part to favorable overwinter-ing conditions. Western spruce budworm, wide-spread at epidemic levels, also contributed to ahigh incidence of damage in at least two seed or-chards. A Douglas-fir coneworm, Dioryctria pseu-dotsugella, infested most cones throughout theKamloops Region and parts of the Cariboo andVancouver regions. Douglas-fir cone moth,Barbara colfaxiana, infested up to 85% of thecones (average 28%) at 34 sites in four regions,although most of the damage occurred in theKamloops Region and the eastern part of theNelson Region. Spruce cone maggot, Lasiommaanthracina, infested up to 80% of white and En-gelmann spruce cones at 12 sites mainly in thePrince Rupert, Prince George, and Nelson re-gions. A spruce seed moth, Cydia strobilella, in-fested up to 70% of the white spruce cones innorthern regions and up to 85% of the Engel-mann spruce near Creston in the Nelson Region.A pine cone borer, Eucosma rescissoriana, infest-ed 30% of the shore pine cones at Mayer LakeProvincial Park on the Queen Charlotte Islands;this was the first record of the insect on theislands.

Ten coastal and two interior seed orchards weresurveyed in 1987. For the second consecutiveyear, Cooley spruce gall adelgid, Adelges cooleyi,severely infested Douglas-fir in five coastal seedorchards and up to 25% of the Sitka spruce infour orchards. Balsam woolly adelgid, Adelgespiceae, lightly infested twigs of up to 35% of theamabilis fir in three orchards near Victoria andanother near Nanaimo; all are within the infesta-tion and regulation zones. A previously undes-cribed gall midge, Contarinia sp., galled buds ofyellow cedar seed orchard stock at three locationson southern Vancouver Island. Up to 4% of themale and 2010 of the female cones at one locationwere affected. Western red cedar midge, Mayetio-

32

la thujae, damaged up to 40% of the cones in twoorchards. Control actions using Dimethoate wereimplemented in most coastal seed orchardsagainst moderate to high populations of Douglas-fir gall midge, Contarinia oregonensis, (90% ofcones infested), Douglas-fir conemoth (45%),and fir coneworm (55%). Ground and aerial ap-plications of Sevin and Bacillus thuringiensis weremade at Skimikin seed orchard against high num-bers of western spruce budworm.

Pests of Young Stands

As part of an ongoing province-wide survey, cur-rent damage by about 35 active pests was identi-fied on 12 conifer hosts in 62 stands (60% plant-ed, 40% natural; 2 to 25 years old) in five forestregions. Most common was Cooley spruce galladelgid which lightly infested new growth ofthree spruce hosts and Douglas-fir in 20 stands.Pine stem and branch rusts were also found.Western gall rust, Endocronartium harknessii, in-fected an average of 11% of the lodgepole pine in17 stands. Cronartium species were on 11% of thelodgepole pine in nine stands in the PrinceGeorge Region, and white pine blister rust, C.ribicola, killed or infected 21% of the white pinein three stands in the Nelson and Vancouver re-gions. Warren's root collar weevil, Hylobius war-reni, killed an average of 4% (range 1 to 6%) ofthe young lodgepole pine in three plantations inthe Prince George Region.

Sclerophoma pithyophila, a dieback disease ofDouglas-fir which usually follows drought, frostdamage, and other injuries, infected up to 20% of10- to 12-year-old Douglas-fir in three planta-tions in the Cariboo Region causing dieback of35 cm to 1 m. Most of the Douglas-fir in 1982plantations at Tsekut Lake southwest of StuartLake in the Prince George Region and nearWhiskers Point on McLeod Lake were poorlyformed with multiple tops, dead leaders, and la-teral branches; this was attributed to infection byS. pithyophila.

Infection by Atropellis piniphila in young stands atOpatcho Lake in the Prince George Region was29% in nonspaced areas but less than 1% inspaced areas. However, western gall rust, Endo-cronartium harknessii, was more common, infect-ing 40% of the trees in spaced stands and 34% ofthe trees in nonspaced stands. In natural stands

near Tumbler Ridge, British Columbia andRancheria in the Yukon Territory, the rust infect-ed up to 25% of the regeneration lodgepole pine.Comandra and stalactiform blister rusts infectedonly 1% of the young lodgepole pine in fourstands from Prince George to the Cassiar High-way and four locations in the Yukon Territoryfrom the Hyland River Valley to near Atlinincluding Takhini Forest Reserve nearWhitehorse.

The incidence of leader mortality in immaturelodgepole pine stands caused by Pissodes termi-nalis in the western part of the Cariboo Regiondeclined to less than 7% overall from about 16%in 1986. Stands examined were along the Tasekoand Palmer lake roads. There was a significant re-duction in broods by undetermined causes instands near Trout Creek in the eastern part of thePrince Rupert Region. Although leaders attackedin 1986 were dead, 70% did not contain broodseven though egg-laying niches were evident. AtAndrews Bay near Ootsa Lake, 90% of the early-instar larvae were dead in pine terminals attackedin 1986.

Animal damage

Mortality of recently planted conifer seedlingssuspected to be caused by high numbers ofmeadow voles, Microtus sp., increased signifi-cantly in the eastern part of the Prince RupertRegion. This resulted in adjustments to sitepreparation plans in some areas. Feeding on seed-ling stems was more common but less severe inpoorly burned and nonburned sites than inburned sites. Buds and branches below patches ofbark chewed by voles, particularly in nonburnedsites, are expected to survive.

The greatest vole damage was at Crow Creek andMaxan Lake west of Burns Lake where 37% ofthe 1986 planted lodgepole pine and 16% of thewhite spruce were killed and another 24% dam-aged. Seedling mortality at three sites northeastof Telkwa at Covert Creek and near TanglechainLake was 30% and 10% in two nonburned sitesand 20% in a burned site; seedling damage was30%, 30% and 16% at the three sites. At LampreyCreek, 45% of the seedlings planted in 1985 weredamaged (38%) or killed (7%), and 30% weredamaged at Andrews Bay. In a 1986 burn atPoplar Lake, 35% of the stock planted in 1987

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were damaged and 5% were killed by girdling. Inan adjacent plowed, nonburned area, 20% of theseedlings were killed and 50% were severelydamaged.

Up to 45% of the young pine in 3 of 15 coniferplantations near Ootsa and Maxan lakes wereseverely girdled near the base, possibly by hares.An additional 50% of the trees were lightlydebarked. Most severe damage was to 9-year-oldconifers in a 15-ha area near Ootsa lake. Damageat two other sites was severe on up to 16 % of 6-year-old trees and light on 20% of 4-year-oldtrees. Feeding damage was present at the remain-ing 12 plantations at very low levels.

Patches of bark were chewed by porcupines fromthe stems and branches of conifers in young andsemimature stands in the western part of thePrince Rupert Region. This is expected to resultin continuing widespread tree mortality.

Climatic injury

Mortality of terminals of regeneration whitespruce attributed in part to late frost has occurredevery spring for the past 5 years in the easternpart of the Prince Rupert Region, most notice-ably in the Kispiox TSA. Assessments this yearindicate 20% of the terminals in young sprucestands at Date and Kuldo creeks have been killedsince 1982, of which nearly half (45%) now havemultiple leaders. Near Goosly Lake, 12% of the10-year-old white spruce had developed multipleleaders due to dead terminal buds; an additional7% on better sites had only single leaders.

East of Meziadin Lake in the Prince RupertRegion about 80% of the planted Sitka sprucehad multiple deformities and breakage fromprevious years' snowfall. Stem deformity,

broken branches and forked tops caused byheavy wet snowfall affected most Douglas-fir in a1974 plantation at Crawford Creek near Crestonin the Nelson Region. Similar damage wascommon in overstocked regeneration lodgepolepine elsewhere in the East Kootenay includingTeepee, Weaver, and Kutlits creeks.

Acid rain monitoring

Since 1984, observations for acid rain symptomsor symptoms which mimic those of acid rainhave been made in British Columbia at 15 perma-nent plots and more than 590 permanent samplestations by FIDS rangers as part of the Acid RainNational Early Warning System. Symptomsdirectly attributable to acid rain, including prema-ture needle discoloration and loss of needles,have not been seen. About 20 tree species andnumerous species of ground cover were generallyhealthy. Damage observed was usually attributa-ble to previous or current pest conditions.

Fume damage

Older needles of mature western hemlock on theeast side of Neroutsos Inlet on Vancouver Islanddiscolored by sulphur dioxide emissions from anearby pulp mill at Port Alice were less evidentthan in 1986. Interveinal discoloration of alderand salmonberry was very light over about 10 haabout 1 km east of the mill; conifer foliage wasnot usually affected. New shoots of hemlock overabout 240 ha 1 km north of the mill were appar-ently healthy.

The impact of periodic fume emissions on coni-fers east of Kimberley is being evaluated on plotsestablished by the Forest Insect and DiseaseSurvey of the CFS in the late 1960s.

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Deciduous and Ornamental Tree Pests

Tent caterpillarsMalacosoma spp.

Defoliation of deciduous trees and shrubs by in-creased populations of forest tent caterpillar,Malacosoma disstria, was more severe and wide-spread in parts of the Cariboo, Kamloops,Nelson, and Prince George regions than in 1986but declined in the Peace River area (Map 4).Western tent caterpillar, M. pluviale, populationsin southwestern British Columbia declined dueto increased virus infection, which resulted inless severe defoliation of mixed deciduousstands, including alder, than in 1986. Populationsin the Okanagan Valley increased for the secondconsecutive year.

Forest tent caterpillar populations around PrinceGeorge increased significantly and defoliatedtrembling aspen in 70 separate infestations over8300 ha, up from 580 ha in 1986. Defoliation,mainly west and northwest of Prince George nearChief and Nukko lakes in the Salmon Riverdrainage and east near Tabor Mountain, was lighton 26% of the area, moderate on 43%, and severeon the remainder.

Declining populations in the Peace River areacaused light and moderate defoliation of about 55aspen and cottonwood stands over 8650 ha,down from 91 700 ha in 1986. The decline in thefifth year of infestation in some areas was mainlyin the Pine River Valley west of Fort St. John andsouth to Tupper and between the KiskatinawRiver and Groundbirch. Cold wet weather in thearea during larval activity may have contributedto the decline.

In the Nelson Region, trembling aspen, cotton-wood, and birch in about 120 separate standsover 7250 ha were moderately or severely defo-liated by forest tent caterpillar, mostly near Trail,Rossland, Castlegar, and Slocan. This was a six-fold increase from 1986 and the fourth consecu-tive year of defoliation in some areas. Numeroussmall pockets of mixed deciduous stands fromCreston to Golden were lightly defoliated andseveral cottonwood stands totalling 200 ha near

Kitchener and in the Kootenay River Valley nearFort Steele, Wardner, and Galloway were severe-ly defoliated for the first time in 10 years.

Increased forest tent caterpillar populations inthe Kamloops Region severely defoliated poplar,willow, maple, and birch over about 5 ha at thesouth end of Monte Lake and along Chase Creeksouth of Falkland. In the North Thompson RiverValley, where the last infestation in the region oc-curred in 1979, willow and maple over 20 hasouth of Barriere were severely defoliated.

There was no evidence of populations betweenKitwanga and Moricetown in the Prince RupertRegion where populations collapsed in 1986 fol-lowing 2 successive years of high numbers anddefoliation of aspen over 900 ha.

Egg mass samples from five recently infestedstands in the Prince George Region including thePeace River area indicate continuing populationsand variable intensities of defoliation in 1988.Defoliation is also forecast to continue in theNelson Region in the West Kootenay betweenRossland and Slocan, and in the Kootenay RiverValley near Fort Steele.

Western tent caterpillar colonies in southwesternBritish Columbia were numerous and wide-spread, in some areas for the seventh consecutiveyear. In most areas, however, up to 50% of thelarvae were infected and killed by nuclear poly-hedrosis virus before they matured. This resultedin significantly less defoliation throughout theFraser Valley, the Sunshine Coast, the Gulf Is-lands, and in east coastal areas on VancouverIsland than was expected considering the highnumbers of young larvae and numerous coloniesearlier in the year.

Alder and white birch over about 100 ha nearHagensborg and near Belarko in the Bella Coolaarea of the Vancouver Region were lightly toseverely defoliated by western tent caterpillar.This is the first record of this defoliator in themid-coastal area of British Columbia.

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Colonies of western tent caterpillar were alsomore common and widespread in the OkanaganValley than in 1986. Defoliation of small pocketsof alder, birch, and other deciduous trees andshrubs ranged from light to moderate in thenorth Okanagan and from Vernon east to Lumbyand south to Kelowna. Near Penticton, mixeddeciduous stands covering up to 10 ha were light-ly to moderately defoliated.

Newly developing infestations in the Bella Coolaand Okanagan valleys are expected to continue in1988, but virus-infected populations insouthwestern British Columbia should declinefurther.

Gypsy mothLymantria dispar

About 8244 pheromone-baited sticky traps weremonitored throughout British Columbia in thethirteenth year of the cooperative program withAgriculture Canada (Plant Health), the BritishColumbia Forest Service, and the Forest Insectand Disease Survey of the CFS.

In total, 221 adult male gypsy moths were cap-tured in 56 traps in six areas compared with 24moths in 19 traps in 1986. Males were caught forthe second consecutive year at Kelowna (194, upfrom 7 in 1986) and near Canadian Forces BaseEsquimalt (5, up from 3 in 1986). New catcheswere made at Qualicum Beach (1) and Parksvilleon Vancouver Island (12), and near Tsawwassensouth of Vancouver (3). New egg masses werefound at Kelowna (30), Belmont Park (7), andParksville (3), where 29 old egg masses were alsofound.

No adults were found in 282 traps set by theForest Insect and Disease Survey of the CFS in233 forested recreation areas in national and pro-vincial parks, commercial campgrounds, nearmilitary bases, and north coastal ports.

Intensified monitoring and periodic control pro-grams have prevented establishment of gypsymoth populations in British Columbia and defoli-ation has not been observed. Following 3 years ofpositive trapping and four applications of Bacillusthuringiensis in 1987, no adults were captured atChilliwack. Potential quarantine restrictions andcostly control programs remain the major con-

cerns of the forestry sector should populationsbecome established.

Male adult trapping, and, when necessary, eggmass surveys will continue in 1988 in cooperationwith Agriculture Canada (Plant Health) and theBritish Columbia Ministry of Forests and Lands.

Satin mothLeucoma salicis

Black cottonwood in a small stand at Stump Lakesouth of Kamloops was severely defoliated. Else-where in the Kamloops Region, populationswhich had defoliated small areas of tremblingaspen during the previous 2 years were at endem-ic levels.

Western winter mothErannis tiliaria vancouverensis

Mixed deciduous stands in the North ThompsonRiver Valley in the Kamloops Region were defo-liated for the second consecutive year. In adjacentparts of the Cariboo Region stands were defoliat-ed for the first time in 10 years. Patches of mixed-age birch, maple, and poplar of up to 50 ha be-tween Barriere and Clearwater were moderatelyto severely defoliated, particularly west of LittleFort at Eakin Creek where stands were defoliatedfor the first time in 1986. White birch along thesouth shore of Mahood Lake in the eastern partof the Cariboo Region was lightly to moderatelydefoliated for the first time. Scattered pockets ofmaple and willow in the Vancouver Region werelightly or severely defoliated by increased popula-tions near Boston Bar, in the Skagit River Valley,and in Golden Ears Provincial Park near Haney.Previous infestations, the last in 1972 near Pem-berton, declined after 2 years.

Infestations of 2 to 3 years in duration have oc-curred periodically since 1949 in coastal and inte-rior deciduous forests. Currently high popula-tions in the interior are expected to remain so in1988, particularly in the Clearwater area in theKamloops Region. High larval populations in1987 followed very high numbers of adults in thearea in late 1986.

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Winter mothOperophtera brumata

Winter moth, Operophtera brumata, populationson southern Vancouver Island were at very lowlevels for the third consecutive year. Defoliationof deciduous trees and shrubs, mainly Garry oakand maple, was very light and scattered in Great-er Victoria, the Saanich Peninsula, and the west-ern communities. Defoliation was not evident atDuncan, Nanaimo, and Saltspring Island.

Parasitism by the introduced parasitic fly Cyzenisalbicans and the wasp Agrypon flaveolatum re-leased periodically since 1979 and considered asthe major cause of the winter moth decline, wasabout 60% overall in an initial evaluation. Thiswas up from an average of 4 4 % , mainly attributedto C. albicans, in 1984 and 1985.

Poplar leaf and shoot blightVenturia macularis

Increased infections resulted in significantlymore widespread and severe discoloration oftrembling aspen than in recent years in the Cari-boo Region and lesser damage in parts of theNelson and Prince George regions. Infections de-clined in the Prince Rupert Region. Groups ofmoderately infected trees over 1 to 10 ha werecommon from Clinton to 100 Mile House, fromLac La Hache to Quesnel, and from HorseflyLake to Riske Creek and west to Hagensborg. Inthe Nelson Region, increased infection severelydiscolored scattered groves of trembling aspen

near Wasa and between Fairmont and Invermere.Infection in regeneration aspen increased over1986 levels on several hectares along the FortLiard Highway where up to 10% of the crowns ofmost trees were infected. Infection declined be-tween Kitwanga and Cedarvale in the PrinceRupert Region for the second consecutive year;only trace infection in scattered pockets wasfound.

A birch leaf skeletonizerLyonetia saliciella

Discoloration of scattered patches of white birchwas widespread in the northern part of EastKootenay in the Nelson Region, in some areasfor the thirteenth consecutive year. High popula-tions severely defoliated 16 stands over morethan 2000 ha from Forster Creek near Invermerenorth to Golden. Birch stands north of Goldenwere only lightly defoliated.

Poplar-and-willow borerCryptorhynchus lapathi

Willow mortality caused by the poplar-and-willowborer was more common and widespread than in1986, affecting up to 70% of the branches onnumerous willows in the eastern part of the Cari-boo Region and in the Prince George area.Recovery of the borer from the Prince Georgeand McBride areas represents a significant expan-sion of its known range.

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New Records of Occurrence and Distribution

Insect or Disease Host

Remarks and Location

Balsam shoot borer,Argyresthia sp.

Blight on seedlings,Rosellinia minor

Blight on shoots,Sirococcus strobilinus

Blight on shoots,Sydowia polyspora

Canker fungus,Nitschkia molnarii

Cypress bark moth,Cydia cupressana

Dieback fungus,Ascocalyx sp.

Dieback fungus on leaders,Cladosporium sp.

Dieback fungus on branches,Kabatinajuniperi

Dieback fungus,Phacidium gaeumannii

Dieback fungus,Phoma sp.

Dieback fungus,Sclerophoma semenospora

Dieback fungus,Sclerophoma sp.

Dieback fungus,Tympanis laricina

Conifer hosts

Grand fir

Engelmann spruce

Mountain hemlock

Balsam fir

Whitebark pine

Eastern white cedar

Douglas-fir

Western larch

Siberian larch

Rocky Mountainjuniper

Engelmann spruce

Norway spruceDouglas-fir

Western larchWestern hemlock

Siberian larch

Ponderosa pine

Siberian larch

Western white pine

First collection from westernA bies spp.

New record in British Columbiaon seedlings at Maple Ridge

New host record on regenerationnear Port Clements

New distribution record inthe Yukon killed frost damagedterminals

New host record from Smithers

New record of this in BritishColumbia from Kelowna andVictoria

New host record from McLeodLakeNew host record near Houston

New host record at FortNelson

New host record at Savona

New host record in BritishColumbia from HorseflyNew host record at Fort NelsonNew host record at Hope andVavenbyNew host record at Grand ForksNew host record at Nakusp

New host record at Fort St.James

New host record at Rock Creek

New host record at Fort StJames

New host record at Nanaimo

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Insect or Disease Host Remarks and Location

Sitka spruce

Western yew

Whitebark pine

Western hemlock

Deodar cedar

Eastern white cedar

Yellow cedar

Yellow cedar

Lodgepole pine

Western larch

Western hemlock

Larch sp.

White spruce

Black spruce

Grand fir

White spruce

Eastern spruce gall adelgid,A delges abietis

Epiphyte (leaf),Epipoleaum sp.

Epiphyte (bark),Karschia sp.

Epiphyte (bark),Stigmina sp.

Epiphyte,Verrucaria plumbaria

Fletcher scale,Parthenolecanium fletcheri

Fly speck fungus,Leptopeltis sp.

Gall midge,Contarinian. sp.

Hyperparasite on dwarf mistletoe,Cladosporium sp.

Hyperparasite on dwarf mistletoe,Glomerella cingulata

Hyperparasitic fungus,Aegerita fungicola

Larch sawfly,Pristiphora erichsonii

Needle blight,Sphaeropezia sp.

Pale spruce gall adelgid,Adelges strobilobius

Pine needle scale,Chionaspis pinifoliae

Resin midge,Cecidomyia n. sp.

First collection of Europeanspecies in British Columbia atVictoria

New host record at Tofino

New record in British Columbiafrom Smithers

New host record at Courtenay

New host record at Victoria

New host record in BritishColumbia at Penticton andKelowna

New record in British Columbiaat Sooke and Slocan Park

New record in British Columbiaat four sites on VancouverIsland, two in the FraserValley and near Prince Rupert

New host record on dwarfmistletoe seeds at Parson

New host record at ChristinaLake and Grand Forks

New host record at Parksville

New distribution record onexotic larch at Terrace

New record for British Columbiaat Mackenzie

First record in BritishColumbia at Fort St. John -galls

New host record for BritishColumbia at Sidney

New species collected oncontainer stock at Duncan,Skimikin, and Red Rock

Spruce bud scale, Grand firPhysokermes piceae

Spruce gall adelgid. Black spruceAdelges lariciatus

Western gall rust,Endocronartium harknessii

Jeffrey pine

White spruce

Deciduous hosts

Birch

Wood decay fungus,Pholiota squarrosa

Birch leafminer,Fenusa pusilla

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Insect or Disease Host Remarks and Location

New host record at Sechelt

New record for the Yukonsouth of Jakes Corner

New host record associatedwith Sirococcus strobilinus onstressed trees in NorthVancouver

New host record at Sidney

First record in BritishColumbia at Fort Nelson - ingalls

New host record for BritishColumbia at Victoria

New host record at Hazelton

New distribution records atSmithers, Castlegar, Penticton,and Prince George. This is thefirst record of this Europeanspecies beyond Fraser Valley.

New distribution records atNelson, Kamloops, Blue River,and Sicamous. This insect waspreviously recorded at PrinceGeorge in 1985.

Resin fungus, Grand firClaussenomyces olivaceus

Rust, Creeping juniperGymnosporangium nelsonii

Saprophytic fungus, Atlas cedarPithya vulgaris

Birch leafminer, White birchProfenusa thomsoni

Canker on stem and branch, Siberian elm New host record for BritishNectria cinnabarina Columbia at Merritt

European mountainash

New record for the Yukonat Takhini Forest Reservenear Whitehorse

New host record for the Yukonat Teslin

New record for British Columbiaat Revelstoke

New host record for BritishColumbia at Victoria

Dieback (branch)Tympanis sp.

Dieback (twig)Godronia multispora

Gall fungus,Gloeosporium sp.

Trembling aspen

White birch

Oak