Forest insect and disease conditionsBritish Columbia & Yukon

1984

C.S. WoodG.A. Van Sickle

andT.L. Shore

Canadian Forestry ServicePacific Forest Research Centre

BC-X-259

1985

Canadian Forestry ServicePacific Forest Research Centre

506 West Burnside RoadVictoria, B.C.

V8Z 1M5

© Minister of Supply & Services Canada, 1985ISSN 0705-3274

ISBN 0-662-13710-8Cat. No. Fo46- I7/259E

Abstract

This summary of forest pest conditions in BritishColumbia and the Yukon in 1984 was compiledfrom records and field reports of 11 Forest Insectand Disease Survey technicians. Emphasis is ondamaging pests that are, or may become, majormanagement problems. Thirty-nine forest pestsare discussed in detail and some predictions aremade for 1985. Mountain pine beetle killed482 000 ha of mature pine, mainly in the CaribooRegion. Spruce beetle infestations in the PrinceGeorge and Prince Rupert regions declined to46 300 ha. The area of Douglas-fir forests defo-liated by western spruce budworm declined to62 000 ha. Douglas-fir tussock moth populationscollapsed to only 160 ha following three years ofthe most severe and expansive recorded out-breaks. A new outbreak of eastern spruce bud-worm defoliated 7 300 ha of fir-spruce stands inthe Liard River Valley. Western hemlock looperinfestations expanded in the Cariboo and Kam-loops regions to 13 350 ha, but collapsed in theNelson Region following two years of severedefoliation. Increased western blackheaded bud-worm populations lightly defoliated 19 000 haold growth western hemlock and western redcedar in the Revelstoke area. Gypsy moth adultswere trapped on Vancouver Island, for thesecond consecutive year, and on the Lower Main-land.

Résumé

Cet aperçu des conditions relatives aux ravageursforestiers en Colombie-Britannique et au Yukonen 1984 a ete établi a partir des données et desrapports d'observation sur le terrain de 11 techni-ciens du Relevé des insectes et des maladies desarbres. On a accordé une importance particulièreaux ravageurs qui représentent ou risquent decauser des problèmes importants de répression.Trente-neuf ravageurs des forêts sont examinésde façon détainée, et des prévisions sont présen-tées pour 1985. Le dendroctone du pin ponderosaa tue des pins a maturité sur 482 000 ha. Les in-festations par le dendroctone de l'épinette ontété réduites a 44 000 ha. Le défoliation des forêtsde douglas taxifolié par la tordeuse occidentalede l'epinette a également diminué, atteignant62 000 ha. Les populations de la chenille ahouppes du douglas se sont effondrées après unepullulation de trois ans. Par contre, une nouvellepullulation de la tordeuse des bourgeons del'épinette dans la vallée de la Liard a défolié 7 300 hade peuplements de sapin et d'épinette. Les infes-tations de l'arpenteuse de la pruche de l'Ouestont progressé dans le centre de la Colombie-Bri-tannique où elles ont sévi sur 13 350 ha, mail sesont effondrées dans la région de Nelson aprèsdeux ans de défoliation grave. Les populations,en hausse, de la tordeuse a tête noire de l'Ouestont défolié légèrement 19 000 ha de pruche occi-dentale et de thuja geant a maturité. Pour la deux-ième année de suite, des spongieuses adultes ontété capturées dans L'île Vancouver; des capturesont egalement été faites dans les basses terres dela partie continentale.

5

Table of Contents

INTRODUCTION 6SUMMARY 7PINE PESTS 9

Mountain pine beetle 9Needle diseases 12Pine engraver beetle 13Pine sawfly 13Pinewood nematode 13European pine shoot moth 13

SPRUCE PESTS 14Spruce beetle 14A spruce engraver beetle 16Spruce aphid 16A spruce budworm 17

DOUGLAS-FIR PESTS 17Western spruce budworm 17Douglas-fir tussock moth 19Douglas-fir beetle 19Needle diseases 21Western false hemlock looper 21

ALPINE FIR PESTS 21Budworms 21Western balsam bark beetle 22Shoot blights 22Balsam woolly aphid 22Fir coneworm 22

HEMLOCK PESTS 23Western hemlock looper 23Western blackheaded budworm 23Terminal crook disease 23

LARCH PESTS 25Larch casebearer 25Larch sawfly 25Larch budmoth 25Larch needle diseases 26European larch canker 26

MULTIPLE HOST PESTS 26Root and stem rots 26Black army cutworm 27Rodents 27Climatic injury 28Cone and seed pests 28Acid rain monitoring 28Stand improvement assessments 29

DECIDUOUS AND ORNAMENTAL TREE PESTS 30Tent caterpillars 30Poplar shoot blights 31A birch leaf miner 31Striped alder sawfly 31Gypsy moth 31Satin moth 31Western oak looper 31Winter moth 32Dogwood leaf blotch (Anthracnose) 32Cypress tip moth 32

INTRODUCTION

The six Forest Insect and Disease Survey units ofthe Canadian Forestry Service are responsible forproducing a national overview of important pestconditions and their implications; maintainingrecords and surveys to support quarantines; sup-porting forestry research through maintenance ofrecords, herbaria, and insect collections; andproviding advisory services concerning forestinsect and disease conditions. General surveys todetect and monitor important insects and dis-eases are conducted annually in the PacificRegion with the cooperation of the BritishColumbia Ministry of Forests and other federal,provincial, industrial, and municipal agencies.The close cooperation with research programsand staff at the Pacific Forest Research Centrecontinues to be an important contribution.

This regional report reviews the impact andstatus of major forest insects and diseasesthroughout British Columbia and the Yukon Ter-ritory in 1984 and forecasts some pest conditionsfor 1985. The information is compiled primarilyfrom the observations and field records of elevenForest Insect and Disease Survey Rangers duringtheir field assignments extending from late Mayto October. More detailed information for eachprovincial forest region is available in file reportscompiled by the following rangers.

Cariboo Forest Region— Dick Andrews

Kamloops Forest Region— Bob Erickson; Bob Ferris

Nelson Forest Region— Peter Koot; Rod Turnquist

Prince George Forest Region— Rod Garbutt; Jim Loranger

Prince Rupert Forest Region— Leo Unger; Nick Humphreys

Vancouver Forest Region— Roly Wood; John Vallentgoed

Other staff of the Forest Insect and DiseaseSurvey project in 1984 were as follows:

— Bob Duncan, Insectary Technician— David Evans, Entomologist i/c Insectary

and Collection— John Hopkins, Pathologist i/c Herbarium— Daphyne Lowe, Herbarium Technician— Erika Pass, Insectary Technician— Terry Shore, Pest Survey Sampling Officer— Walter Stanek, Mensuration— Joan Strobbe, Secretary— Allan Van Sickle, Head of the Forest Insect

and Disease Survey Unit— Colin Wood, Chief FIDS Ranger

SUMMARY

Tree and insect development was delayed by 2-4weeks and foliar diseases intensified followingnear-record cool temperatures, subnormalamounts of sunshine and higher than normal pre-cipitation in May and June. This followed gener-ally normal winter weather but high winds inApril caused extensive windthrow and breakageof mature white spruce and lodgepole pine in thecentral and northwestern Interior. Although Julyand August were relatively sunny and dry, insectdevelopment was later than normal.

The most significant insect problem of matureforests in British Columbia continued to bemountain pine beetle, which since 1972 haskilled more than 175 million lodgepole pine. Anestimated 41 million trees (12.1 million m3)were killed over 482 000 ha, up slightly from1983. Most infestations, mainly in the Caribooand Kamloops regions, continued to intensifyand expand.

Spruce beetle infestations, mainly in the PrinceGeorge and Prince Rupert regions, declined forthe second consecutive year to 46 320 ha (1.7million m 3 ) from 58 600 ha (3.3 million m3).

In parts of the Queen Charlotte Islands and somecoastal areas of the Prince Rupert Region, in-creased spruce aphid populations killed up to 4%of the immature and seedling Sitka spruce, andmoderately to severely defoliated most other ageclasses.

The area of Douglas-fir forest defoliated by west-ern spruce budworm, mainly in the Kamloopsand Cariboo regions, declined 16% to 62 000 haof mainly light and moderate feeding. A localizedarea was affected in the Nelson Region. For thefourth consecutive year defoliation did not occurin the Vancouver Region.

Douglas-fir stands defoliated by Douglas-firtussock moth declined from 23 475 ha in 1983 toonly 160 ha near Cherry Creek west of Kam-loops. Previously active infestations in theCariboo, Nelson and Vancouver Regions col-

lapsed. The decline, caused by a naturally occur-ring nuclear polyhedrosis virus and parasites,severely reduced the number of egg masses in1983. Tree mortality of mainly immature trees,severely defoliated for up to two years, covered 5500 ha from Cache Creek to Falkland. Douglas-fir beetle attacked severely defoliated Douglas-firnear Falkland.

A new outbreak of eastern spruce budwormlightly defoliated 7 300 ha in the Liard RiverValley. A one-year cycle budworm expanded to2 700 ha of alpine fir-spruce in the Kitimat-Terrace area of the Prince Rupert Region, butpopulations in the eastern part of the Region col-lapsed due to a pathogen. Light defoliation of firand spruce by two-year cycle budworm occurredover 2 000 ha in the Bowron and Willow riverdrainages in the Prince George and Cariboo re-gions and 200 ha in the Nelson Region.

Defoliation of western hemlock and western redcedar stands in the Nelson Region by westernhemlock looper declined to only 100 ha in thisthird year of infestation. As predicted, parasitismwhich affected up to 34% of the 1983 overwinter-ing eggs, was the major cause of the populationcollapse, similar to trends in previous outbreaks.However, localized infestations in the KamloopsRegion almost doubled to 8 000 ha of mainlylight defoliation, and 5 250 ha were lightly toseverely defoliated in the Cariboo Region, fol-lowing a 2 year population buildup.

For the first time since 1975 western blackhead-ed budworm defoliated mature and overmaturewestern hemlock and western red cedar stands inthe Interior wet belt. Following a 2 year popula-tion buildup, about 19 000 ha of mainly light andmoderate defoliation occurred in 240 pocketsfrom Glacier National Park north to GoldstreamRiver in the Nelson Region. Most budworm in-festations were in or adjacent to stands recentlydefoliated by western hemlock looper.

An estimated 41 000 ha of western larch standsbetween Creston and Elko in the Nelson Region

were severely discolored by increased larch case-bearer populations. Populations remained at lowlevels in larch stands in the West Kootenay duein part to periodic releases of introducedparasites. Larch budmoth defoliated 1 100 ha in10 widely scattered stands near Trail and Ross-land, a decrease from 1983. More than 3 000 haof western larch in the East Kootenay weremoderately to severely defoliated by larchsawfly in the third year of infestation, down sig-nificantly from 10 400 ha in 1983.

High numbers of black army cutworm larvaemined up to 35% of the buds and lightly toseverely defoliated spruce and Douglas-fir seed-lings in six newly planted sites in the Cariboo,Prince George and Prince Rupert regions. Seed-ling mortality (10%) was evident in a plantationnorth of Prince George but most larval feedingwas restricted to herbaceous ground cover. Someplanting schedules were adjusted.

Several quarantine related surveys wereconducted:

- Follow-up inspections were negative forterminal crook disease of western hemlockseedlings at three 1981 planted sites on Van-couver Island.

- Gypsy moth was recorded for the secondyear at Courtenay, numerous larvae werefound and 25 moths trapped. Elsewhere,two moths were trapped in East Vancouver,four at Chilliwack, one at Cultus Lake andone at Adams River east of Kamloops.

Moths were not recorded by FIDS in phero-mone-baited traps in forested recreationsites through the province.

- Surveys of 8 border stands for balsamwoolly aphid north of the recent record inIdaho, were negative.

- Examinations for European pine shootmoth in native pines in the Okanagan Valleyand parts of the West Kootenay werenegative.

- Surveys for European larch canker werenegative, but two closely related native sa-prophytic canker fungi were collected insoutheastern British Columbia.

- Although the pinewood nematode was notdetected in lodgepole pine samples or incerambycid beetles which transmit thenematode, some native bacterial and plantpathogenic nematodes were present.

Permanent plots to detect and then monitor earlysigns of acid rain were established at ShawniganLake, Saltspring Island and the U.B.C. ResearchForest near Haney. in addition, tree conditionwas assessed on 417 FIDS Permanent SamplingAreas throughout the province.

In support of the Environment 2000 projects ad-ministered by the C.F.S., pest conditions were as-sessed at 17 forest improvement sites in theKamloops, Nelson, Prince Rupert and Vancouv-er regions.

PINE PESTS

Mountain pine beetleDendroctonous ponderosae

The most damaging pest in British Columbia in1984 continued to be the mountain pine beetle.Since 1972 an estimated 175 million mature pinehave been killed by the beetle in the province(Fig. 1), where pine stands cover more than 14million ha and comprise 22% of the harvest.

Mature lodgepole pine and some western whitepine killed by the 1983 beetle attack coveredmore than 482 000 ha (see map 1), up slightlyfrom last year. More than 7 500 infestations,from the International border in the East Koote-

nay to north of Hazelton, contained an estimated12.1 million m 3 of beetle-killed trees (Table 1),about 18% of the 1982-83 provincial harvest.Losses were greatest in the Cariboo, Kamloops,Nelson and Prince Rupert regions and also oc-curred in the Prince George and Vancouverregions.

Increases in areas of pine mortality, mainly in theKamloops, Prince George and Vancouver regionsand to a lesser degree in the Nelson and PrinceRupert regions, occurred as a result of general ex-pansion of previously infested stands. In addi-tion, nearly 170 000 ha with 'grey' previouslykilled pine stands were mapped; 85% in the Cari-

Table 1. Number and area of mountain pine beetle infestations by provincial Forest Regions, based onrecently killed trees observed during aerial surveys and on limited ground observations, BritishColumbia, 1984.

No. of

infes-tations

Trees KilledaAverage % of Treesb

Region Area(ha)

Number Volume Stands(000) (000 m 3 ) Cruised HC R GP

CaribooKamloopsNelsonPrince GeorgePrince RupertVancouver

5 000 381 000c33 000600 58 000 5 000

21 000 1 8001350150 2 800c270650 14 500c1 212

20 5 000 20

7 6002 734

60097

1 103

20 55 24 12 8 19 66 15 7 10 27 77 7 3 8 5

14 40 24 18 10 8

TOTAL 7 770 482 300 41 302

12 194 50 60 17 10 9 4

a Trees attacked in 1983, discolored in 1984

b H = Healthy; C = Current, attacked in 1984; R = Red, attacked in 1983; G = Grey, attacked prior to 1983, P =Partial attack (strip attack).

Estimates include data from B.C. Ministry of Forests.

PRINCERUPERT

0

• •• •••

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Map 1

FOREST INSECTAND

DISEASE SURVEY

1984

Areas where recent treemortality was detectedduring aerial surveys.

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500

400

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boo Region, and the balance in the NelsonRegion.

Based on surveys in 50 areas, most infestationsare expected to expand and intensify in 1985. Anaverage of 17% (1 to 65% range) of the standinggreen trees were currently attacked, down 5%from 1983.

Early in 1984, pre-emergency brood assessmentsin 31 stands in the Cariboo, Kamloops andNelson regions indicated increasing populationsin most major infestations, but a probable declinein parts of the Prince Rupert Region. The ratio ofsuccessful overwintering progeny to parent bee-tles ranged from 0.6 to 12.8; a factor greater than4.1 indicates a rising population. A slight decreasein current attack in higher elevation stands oc-curred in parts of the Prince Rupert Region dueto mortality of up to 75% of the beetle popula-tions during the winter of 1983-84. The majorityof the broods from 1984 flights developed nor-mally in the Cariboo, Kamloops and Nelson re-gions. In the Prince Rupert Region brood devel-opment was normal in lower elevation and south-ern exposed stands. However, about half thepine which contained 1984 broods had been at-tacked in 1983, and 11/2- to 2-year cycle broodsfrom late 1983 attacks were common.

Outbreaks in the Cariboo Region affected318,000 ha, similar to 1983, and contained morethan 33 million trees (7.6 million m°). This repre-sents 80% of the total provincial outbreak areaand more than 13 times the average area loggedof all species in the region annually. In addition,more than 144 000 ha contained 6.6 million m°of previously beetle-killed lodgepole pine. Themajor expansion of widespread outbreaks wasnorthward from Alexis Creek and Tatla Lake toNazko and Anahim Lake. Current attack in 20 re-cently infested stands west of Riske Creek aver-aged 24% (range 2 to 65%) , down from 31% in1983. The highest average incidence of currentattack was 65% at Mons Lake southwest of RiskeCreek and 47% on the Taseko Lake Road. Else-where in the region current attack ranged from 2to 29% (avg. 20%) in 18 stands. This indicatescontinuing high levels of lodgepole pine mortalityin 1985, the eleventh consecutive year of infesta-tion.

An estimated 600 infestations in the Lillooet andOkanagan TSAs in the Kamloops Region con-

LODGEPOLE PINE MORTALITYCAUSED BY MPB IN BRITISH COLUMBIA

1972 74 76 78 80 82

84

YEARS

Figure 1. Annual area of aerially visible, recent treediscoloration and cumulative number of trees killed bymountain pine beetle, 1972-1984.

tained 5 million trees (2.7 million m°) over58,000 ha, up 24% from 1983. Areas of mortalityexpanded in chronically infested stands nearCarpenter Lake, Goldbridge, Tyaughton andFrench Bar creeks. Major infestations continuedin Mission and Belgo creeks east of Kelowna, inLambly, Shorts, Trout and Hayes creeks west ofthe Okanagan Valley, in the Ashnola RiverValley and in the Stein River Valley west ofLytton. Continuing outbreaks and increased mor-tality are expected in most areas in 1985, basedon an average of 15% current attack in eight rep-resentative stands, down slightly from 18% in1983. The highest incidence of current attack was50% at Hayes Creek near Princeton.

Infestations in the Nelson Region covered an es-timated 21 000 ha which contained about 1.8 mil-lion (600 000 m 3) lodgepole and some white pinein 1350 widespread infestations. Additionally 25000 ha contained mainly dead trees from previ-ous years of infestation. Host depletion fromprevious beetle attacks and harvesting has limitedthe expansion of infestations particularly in theFlathead River Valley and the Bush Arm areanorth of Golden, However, infestations contin-ued elsewhere, including the Caven-Bloomcreeks area near the Montana border, the Whiteand Kootenay river drainages along the Albertaborder, Kootenay National Park and the Colum-

200

160

120

80

40

12

bia and Kettle river valleys. Spot infestations of 2to 45 trees expanded in 7 of 15 valleys along theB.C./Alberta border from Elkford to north ofGolden, remained static in 6 and 2 declined. Con-tinuing but declining outbreaks and tree mortalityare expected in 1985, indicated by 7% currentattack in seven stands, similar to 1983 levels.The highest incidence of attack was 17% nearChristina Lake and 16% near Dutch Creek.

The area, number and volume of lodgepole pinekilled in the Prince Rupert Region increasedslightly to 1.2 million trees (1.1 million m 3 ) on14 500 ha up from 13 300 ha in 1983. The in-creases occurred mainly in the Cranberry Riverdrainage and in the Skeena River drainage be-tween Hazelton and Terrace where aerial surveycoverage was expanded in 1984. Major outbreakscontinued in Harold Price Creek, Morrison,Fulton and Babine lakes areas and in the NassRiver drainage. Outbreaks are expected to con-tinue throughout the Region in 1985 based ontrees currently attacked which averaged 24%(range 5 to 46%) in 15 infested stands, downslightly from 28% in 1983. The regional currentattack remains high, particularly in the Kispioxarea (46%), despite mortality of up to 75% of theoverwintering eggs and early instar larvae inhigher elevation stands in the eastern interior.

In the Prince George Region an estimated 15 000lodgepole pine were killed over about 225 ha inthe Fort St. James area. Also, mortality oflodgepole pine and some western white pine cov-ered 2 600 ha in chronic infestations in maturestands in the Canoe Arm area south of Vale-mount.

Widespread, scattered infestations increased bymore than half in the Vancouver Region to20 000 recent beetle-killed trees in 20 area over5 000 ha. The major expansion occurred in theHomathko River drainage, west of extensive out-breaks on the Cariboo Region. Elsewhere smallinfestations occurred in the Pemberton andFraser Canyon areas. A cooperative beetle con-trol program in Manning Provincial Park has re-duced the number of beetle-infested trees from5 500 in 1981 to only three in 1984. However, athreat of reinvasion exists from east of the Parkwhere 40 groups of 5-10 recently killed lodgepolepine indicate a continuing population buildup.

Needle diseases

Native needle diseases increased in most interiorpine stands. Severe, conspicuous discoloration of1983 needles of lodgepole, white and ponderosapines was widespread in the Kamloops, Nelsonand Prince Rupert regions, and to a lesser degreein the Prince George and Vancouver regions. Fa-vorable, moist conditions during spore dispersaland infection in 1983 also occurred in 1984. Thiscould result in moderate to severe infectionsagain in 1985. Infection declined significantly inthe Cariboo Region following two successiveyears of moderate to severe infection and needleloss.

Red band needle disease, Scirrhia pini was themost common disease on needles of lodgepoleand white pine and was often associated withneedle blights Lophodermella concolor and L.montivaga. Western pine-aster rust Coleosporiumasterum was common in a few areas. Ponderosapine was most commonly infected by Elytroder-ma needle disease, Elytroderma deformans and aneedle blight Leptomelanconium cinereum wascommon in patches in the Nelson Region.

Increased infection of most age classes oflodgepole and white pine by S. pini was wide-spread in the Nelson Region. Up to 80% (avg.50%) of the 1982 and 1983 needles of mostlodgepole pine were infected at Beaverdell, in theWest Kettle and Slocan river valleys, and nearSalmo, Creston, Invermere and Sparwood. Thiswas the third consecutive year of severe infectionand discoloration in many immature white pinestands in the Slocan Valley.

In the Kamloops Region widespread moderate in-fections of lodgepole pine by L. concolor and L.montivaga also increased, particularly in theThompson River drainage. The areas of lodge-pole pine affected in the Blackwater, Fort St.James, Vanderhoof and Fraser Lake areas in thePrince George Region generally declined slightlyfrom 1983, and trees were less severely infected.However, pines in provenance trials at Red Rockwere severely infected for the second year. Northof Hazelton in the Prince Rupert Region 75% ofthe needles on 10% of the young lodgepole pinewere infected and discolored. For the second suc-cessive year immature lodgepole pine on Van-couver Island were lightly to moderately infectednear Parksville and at the south end of Buttle

13

Lake. Infection in lower elevation mature pinestands near Lightning Lake in Manning Park in-creased to moderate and severe.

Elytroderma needle infections on ponderosa pineincreased throughout much of the host range forthe third consecutive year, with systemic infec-tion often resulting in severe brooming. Up tohalf (avg. 30%) of the year-old needles were in-fected on most of the trees over widespread areasfrom the Okanagan Valley to Kamloops. Severelyinfected stands were common from AnarchistMountain to Midway and near Creston in theNelson Region.

Infection of previous year's needles of ponderosapine by L. cinereum in the Koocanusa area in theNelson Region were common but lighter than in1983. In localized stands 25% of the needles onmost trees were infected, and repeated annual in-fections since 1979 have resulted in significantneedle loss. Vigor reduction, increment loss andpredisposition of trees to secondary bark beetleattacks could result.

Pine engraver beetleIps pini

Increased current attacks in recently windthrownmature lodgepole pine ranged from 5 to 10 per1000 cm 2 of stem surface area in the Nazko,Palmer and Puntzi lakes areas in the CaribooRegion. Sixty percent of the slash was infested ina recently thinned stand near Cedarvale in thePrince Rupert Region.

Following one or two years of population build-up, patches of healthy trees are often attackedand killed. This could occur in some of theseareas in 1985.

A pine sawflyNeodiprion sp.

For the second consecutive year, increasedsawfly populations severely defoliated most ageclasses of shore pine in the Masset Sound area ofnorthern Graham Island on the Queen CharlotteIslands. At Nache Creek infestations expandedfrom about 20 ha to about 200 ha. Defoliation isnot expected to occur in 1985 as infestations usu-ally decline following one or two years of defolia-

tion. Heavy mortality of shore pine on coastal is-lands was reported in 1977 following severe defo-liation in 1975.

Pinewood nematodeBursaphelenchus (lignicolus) xylophilus

This nematode, responsible for mortality ofpines over large areas in Japan during the past 30years, was recently discovered in Manitoba andthe United States. Surveys of pine stands in Brit-ish Columbia for this nematode were negativefor the fourth consecutive year.

Although 25 lodgepole pine samples and threeadult cerambycid beetles, which transmit thenematode from dead to live pines, did not containB. xylophilus, native bacterial feeding and plantpathogenic nematodes were successfully isolatedfrom coastal and interior pine stands.

Branch flagging and dead mature lodgepole pinewere observed adjacent to recently harvestedstands at Luno Creek and in the Zymoetz RiverValley in the Prince Rupert Region. A causalagent was not identified.

European pine shoot mothRhyacionia buoliana

Since specific surveys for the introduced pestwere concluded in 1981, damage or spread tonatural pine stands has not been observed fromthe adjacent, previously infested exotic pines inthe Kamloops and Nelson regions.

14

SPRUCE PESTS

Spruce beetleDendroctonus rufipennis

Chronic infestations, mainly in the PrinceGeorge and Prince Rupert regions and localizedin the Cariboo, Kamloops and Nelson regions(see map 2), declined 14% overall to 46 320 ha(1.7 million m 3 ) of mature white and Engelmannspruce killed by 1982-83 beetle attack (Table 2).This second year of decline, largely in the PrinceGeorge and Cariboo regions and to a lesserdegree in the Prince Rupert Region, was duemainly to harvesting, trap tree programs and hostdepletion. However, small increases occurred inisolated parts of the Kamloops and Nelsonregions.

Surveys in 19 stands indicate an overall reductionof new attacks to 5% (range 0 to 22%) of the treesin the stand, down from 13% in 1983. Extensiveareas of recent spruce blowdown in northcentralB.C. absorbed much of the current year's attack

in the Prince Rupert Region. This could contri-bute to increased populations and tree mortalityif not salvaged before 1986. Broods in 1984-attacked standing trees in the cruised areas werepredominantly two-year cycle and less vigorousthan in previous years.

Recent mortality of mature spruce in the PrinceGeorge Region declined 25% overall to 26 120 ha(523 700 m 3 ). The decline was mainly in theBowron and McGregor river drainages, howeverin the Goat River drainage the area of the mor-tality increased 7 fold to 2 250 ha. The volume ofspruce harvested in beetle-infested stands in theBowron River Valley totalled an estimated 9 mil-lion m 3 during the past three years. In surveys ofthree previously infested stands in the BowronRiver drainage, current attack was not evident.This is attributed to the greatly reduced emer-gence of broods from previously infested trees.Beetle populations in other stands in the Regionwhich were not examined are expected to contin-

Table 2. Number and area of spruce beetle infestations by provincial Forest Region basedon recently killed trees observed during aerial surveys and limited groundobservations, British Columbia, 1984.

Region

No. of

Infes-tations

Area(ha)

Volume

killed(000 m3)

No. of

StandsCruised

Average % of Treesa

HC R GP

Cariboo 6 2 200 22Kamloops 9 700 1 — — — — —Nelson 115 3 700 116 1 77 7 3 8 5Prince George 490 26 120b 524 3 45 0 15 25 15Prince Rupert 400 13 600b 1 116 15 47 8 17 14 14

TOTAL 1 020 46 320 1 779 19 57 5 12 15 11

a H = Healthy, C = Current, attacked in 1983; R = Red, attacked in 1981-82; G = Grey, attackedprior to 1981; P = Partial attack

b Estimates include data from B.C. Ministry of Forests

PR, RUPERT

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KAMLOOPS

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Map 2

FOREST INSECTAND

DISEASE SURVEY

1984

Areas where recent treemortality was detectedduring aerial surveys.

Spruce beetle

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PRINCERUPERT

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Canadian Forestry Service / Forest Insect and Disease Survey

16

ue, but at reduced levels.

Infestations in Bowron Lake Provincial Park inthe Cariboo Region declined for the second yearby nearly half to 2 200 ha. The decline reducedthe number of widely scattered infested stands tosix along the eastern park boundary.

Mortality occurred in 400 infestations in thePrince Rupert Region, where 13 600 ha ofmature spruce were killed by 1982-83 beetleattacks, down 18% from 1983. The largest areasof tree mortality, mainly in chronically infestedstands, were in the Morice, Fulton and Bell-Irving river drainages and near Ootsa Lake. Treemortality is expected to continue in 1985 but atreduced levels. Currently attacked trees rangedfrom 3 to 22% in 15 stands. The decline in currentattack in standing green trees is mainly the resultof the attraction of the 1984 beetle flight torecent widespread spruce blowdown. Spruce bee-tle lightly attacked 20 mature, water-stressedSitka spruce near Yakoun Lake on Graham Is-land in the Queen Charlotte Islands. This is thelargest recorded number of standing trees at-tacked on the Islands in 70 years. However, themajority of the broods were pitched out or hadnot developed successfully.

Spruce beetle attacked 15 standing and eightfelled mature spruce between km 70 and 83 onthe Haines Road between the Yukon and Alaskaborders in the Prince Rupert Region. In the thirdyear of beetle attacks in the area, the number ofbeetle-killed trees has declined from 300 in 1983.This follows a CFS-FIDS and Canada PublicWorks cooperative program of marking and indi-vidual tree removal to reduce populations intrees injured by a road improvement project.Moderate populations of a secondary bark beetle,Polygraphus rufipennis infested bark strips offelled and partially peeled trees in the area.

In the Nelson Region, scattered pockets of mor-tality of mature spruce increased to 250 ha in thesecond year of infestation at the southern boun-dary of Glacier National Park. Surveys indicated7% of the spruce in the area were attacked in1984 and 9% in previous years. A predominantlytwo-year cycle population will emerge in 1985and threaten mature spruce stands mostly in thepark. Elsewhere in the Nelson Region widespreadinfestations increased from 1 700 ha to 3 700 ha.Most infestations were associated with previously

beetle-infested areas at Top of the World Provin-cial Park and Upper Bull River Valley in the EastKootenay, and in the Upper Arrow Lake drainageincluding the upper Duncan River Valley in theWest Kootenay.

Localized areas of recently killed spruce in theKamloops Region expanded twofold to 700 ha.The largest areas were in Connel (240 ha) andMcGillivray creeks (245 ha) north of AndersonLake. New spot infestations developed in scat-tered areas in the Upper Adams and NorthThompson river drainages; east of Vernon andnorth of Chase.

Spruce engraver beetleIps perturbatus

This beetle, which normally breeds in slash andtops of mature spruce beetle-killed trees, at-tacked and killed tops of mature standing greentrees adjacent to spruce beetle-infested standseast of Prince George. The highest incidence oftop mortality was widespread in the McGregorand Torpy river valleys, where more than 3000mature spruce were affected, particularly in thePass Lake area. Top-killed trees were alsocommon, but less numerous, in the BowronRiver drainage.

Spruce aphidElatobium abietinum

A second consecutive year of continuing highaphid populations resulted in scattered mortalityand moderate to severe defoliation of seedlings,immature and mature Sitka spruce throughoutthe Queen Charlotte Islands and to a lesserdegree in coastal areas between Prince Rupertand Port Edward. In two plantations on MoresbyIsland 4% of the immature trees were killed and2% of the recently planted seedlings on GrahamIsland were killed. Tree mortality, particularly ofimmature open growing spruce can be expectedto increase in the Region in 1985 if high popula-tions and severe defoliation continue. Increasedpopulations on Vancouver Island severely defo-liated seed orchard trees near Victoria, and lightto moderate defoliation of shoreline spruce wascommon in coastal areas from Jordan River toCampbell River and between Ucluelet and To-fino.

17

A spruce budwormZeiraphera vancouverana

Increased populations lightly defoliated lateraland terminal buds of valley bottom, immatureand mature spruce in the Skeena River Valleyfrom Exchamsiks to Prince Rupert. Since the1950s, three previous outbreaks in the westernpart of the Region and on the Queen Charlotte

Islands, each of about five years duration, re-sulted in dead buds and deformed laterals andterminals, particularly on immature trees.

On Vancouver Island 40 to 60% of the buds wereinfested on most shoreline spruce between LongBeach and Tofino, and light populations werecommon in coastal stands in the Port Renfrewarea near Campbell River.

DOUGLAS-FIR PESTS

Western spruce budwormChoristoneura occidentalis

About 62 000 ha of immature and mature Doug-las-fir forests in the province, mainly in the Kam-loops and Cariboo regions and a localized area inthe Nelson Region, were defoliated by the bud-worm in 1984 (see map 3), down from 73 550 in1983.

Most of the 43 000 ha of mainly light and moder-

ate defoliation in the Kamloops Region was inthe Kamloops Lake — North Thompson Riverarea. Patches of light to moderate defoliation oc-curred on 2 150 ha in the Lillooet area, but out-breaks in the Cache Creek-Ashcroft-Savonaareas declined to 900 ha following 10 to 12 suc-cessive years of moderate to severe defoliation.Very low larval budworm populations were re-corded for the first time in stands defoliated byDouglas-fir tussock moth in the Monte Lakearea.

Table 3. Western spruce budworm adults in pheromone traps, egg mass counts and pre-dicted defoliation in 1985 in the Cariboo, Kamloops and Vancouver regions.

No. of stands Avg. No. adults No. egg masses

PredictedRegion sampled per trap /10m 2 of foliage

defoliation

at 0.1% concentration

19851

Cariboo 4

324 severeKamloops

9

72

57

moderateVancouver

12

14 nil

TOTAL 25

Up to 50 egg masses per 10 m 2 foliage = light defoliation51 to 150 egg masses per 10 m 2 foliage = moderate defoliationMore than 151 egg masses per 10 m 2 foliage = severe defoliation

Map 3

1/2

FOREST INSECTAND

DISEASE SURVEY

1984

■Areas where current de-foliation was detectedduring aerial surveys.

One- and Two Year CycleSpruce Budworm

2. Western Spruce Budworm3. Western Hemlock Looper

PR. RUPERT

PRINCERUPERT

0 100 200 km1

0 40 80 120 moL I 1 1

Canadian Forestry Service / Forest Insect and Disease Survey

Outbreaks in the Cariboo Region continued forthe fifth consecutive year, expanding slightly to18 800 ha from 18 500 ha in 1983. Defoliation in-tensities generally declined to light and moderatedefoliation on 17 000 ha in the Clinton area, andsevere pockets on 1 800 ha in the BonaparteRiver-Loon Lake areas. In the Fraser Riverdrainage west of the major outbreak, populationsdeclined to endemic levels.

On average, 6% (range 1 to 8%) of the mixed ageclass Douglas-fir in three permanent study areasnear Savona, Cache Creek and Clinton, werekilled by repeated years of moderate to severebudworm defoliation. Leader mortality, branchand bud dieback affected up to 50% of the under-story trees in stands severely defoliated for twoor more years near Spences Bridge, Ashcroft,Cache Creek and Savona.

In the Nelson Region light defoliation of the cur-rent years foliage of immature Douglas-fir de-clined to only 100 ha at Johnston Creek Provin-cial Park. Populations remained low in previousoutbreak areas in the Fraser Canyon, Hope,Skagit and Manning Park areas of the VancouverRegion and little change is expected in 1985.

The increased number of larvae in beating sam-ples, adults in pheromone traps and egg counts in25 locations in three regions indicate continuingpopulations and defoliation in 1985 (Table 3).Douglas-fir stands west of Clinton are expectedto be the most severely defoliated, and moderatedefoliation is expected in the Kamloops Lake andNorth Thompson River Valley areas. Very lightdefoliation could occur at Johnstone Creek, butnone is expected in the Vancouver Region.

Larval populations were infected by a nuclear po-lyhedrosis virus in five of eight infested standsbetween Lytton and Savona. Nine percent (2 to24%) of the sixth instar budworm larvae wereinfected.

Douglas-fir tussock mothOrgyia pseudotsugata

After three successive years of defoliation ofmature and immature Douglas-fir forests,mainly in the Kamloops Region, populationscollapsed. Current, moderate and severe defolia-tion occurred only over 160 ha near Cherry

Creek west of Kamloops (see map 4), down from23 475 ha in 1983. Small numbers of larvae (lessthan 35 per sample) were collected near Spence'sBridge, but there was no defoliation. Elsewhere,in previously defoliated stands in the Kamloops,Cariboo, Nelson and Vancouver regions popula-tions collapsed. As predicted, the high incidenceof a nuclear polyhedrosis virus and parasites in1983 was a major factor in the decline.

Defoliation is not expected to occur in 1985. Eggmasses were not detected in or adjacent to thedefoliated stands at Cherry Creek. The averagenumber of moths in pheromone-baited trapsagain declined in the Kamloops Region. In theThompson River and Okanagan-Similkameenaverage numbers declined to three and less thanone adult per trap respectively from 68 and 15, in1983.

Tree mortality in previously defoliated standswas mapped in 47 areas totalling 5 500 ha in theKamloops Region. About 3 300 ha containingmortality of young trees occurred near CacheCreek and 2 200 ha near Kamloops, Pritchardand Monte Creek. In 16 defoliated, 2 to 50 hastands mortality of immature trees averaged35%. The highest incidence was at Monte Creekwhere all immature trees over more than 50 hawere killed. Near Cache Creek 90% of the Doug-las-fir regeneration was killed over 30 ha. Highmortality also occurred in stands at HeffleyCreek and Cherry Creek. On the other hand,90% of the mature trees in a study area south ofClinton recovered after two to three years ofsevere defoliation. Trees in most moderatelydefoliated stands are expected to recover but thelarger trees are potentially susceptible to attackby Douglas-fir beetle.

Douglas-fir beetleDendroctonus pseudotsugae

The number and area of recently killed matureDouglas-fir mainly on tussock moth defoliatedstands in the Kamloops Region and in scatteredpockets in the Nelson, Prince George and Van-couver regions declined to about 1 375 ha. Exten-sive harvesting and trap tree programs from Clin-ton to Williams Lake reduced the incidence andarea of 1984 attack in the Cariboo Region, butlight scattered mortality occurred over 1 300 hain the Fraser River drainage from Quesnel to Wil-

3\

1/4 ...VANCOUVER

Map 4

FOREST INSECTAND

DISEASE SURVEY

1984

. Western blackheaded..•budworm

• Douglas-firtussock moth

■ Black army cutworm

CARIBOO

0

NELSON

•

PRINCEGEORGE

0 100 200 km

0 40 80 120 mi1 1 1 1

VANCOUVER

KAMLOOPS-C KAMLOOPS

4,

VICTORIACanadian Forestry Service / Forest Insect and Disease Survey

21

liams Lake and south of Alexis Creek.

From 5 to 60% of the trees (avg. 29%) were at-tacked in 6 of 30 stands previously defoliated byDouglas-fir tussock moth from Hedley to CacheCreek. The highest frequency was at Stump Lakesouth of Kamloops. Groups of 5-20 mature treeswere killed in six areas in Adams, Shuswap andMara lakes drainages in the Kamloops Region.Pockets of 5 to 100 recently killed mature treesoccurred in 20 areas in the West Kootenay fromBoundary Creek to Kootenay Lake and near Pre-mier Lake. In the Blackwater Creek area nearPrince George, 400 trees were attacked. In theVancouver Region scattered attacked treestotalled 530 near Pemberton, in the FraserCanyon area and in Strathcona Park.

Needle diseases

Infection of Douglas-fir needles by Meria sp.,Rhabdocline pseudotsugae, and Swiss needle cast,Phaeocryptopus gaeumannii, increased in imma-ture natural stands and seed orchards in theCariboo, Nelson and Vancouver regions. The in-creased infections are attributed to wetter thannormal conditions in the 1983 spring, and similarconditions this spring could result in similar or in-creased levels of infection in 1985.

Very light infection of the needle disease Merialaricis, common on western larch, was identifiedfor the first time on Douglas-fir in a seed orchardon Vancouver Island. Swiss needle cast was com-mon but light on older needles in young Doug-las-fir stands on Vancouver Island and the Van-couver Mainland.

Up to 50% needle loss due to Rhabdocline needleblight occurred in natural stands over much ofthe eastern Cariboo Region. In the NelsonRegion 25% of the year-old needles were affectedby the blight over areas of 1 to 1 000 ha fromFernie to Creston. Severe infections were exten-sive in patches of immature Douglas-fir stands inthe Bull and White river drainages near Cran-brook and south of Elko.

Western false hemlock looperNepytia freemani

Infestations in Douglas-fir stands in the ShuswapLake-Salmon Arm area collapsed after threeyears of infestation, and after one year near In-vermere and Radium. The high incidence of anaturally occurring nuclear polyhedrosis virus,which affected nearly 75% of the early instarlarvae in the Kamloops Region in 1983, was amajor factor in both regions.

ALPINE FIR PESTS

BudwormsChoristoneura biennis

Choristoneura fumiferanaChoristoneura orae

One- and two-year cycle budworms defoliated12 200 ha of fir-spruce stands in the PrinceGeorge and western part of the Prince Rupert re-gions (see map 3), down significantly from162 000 ha in 1983. Populations in previouslydefoliated stands in the interior of the PrinceRupert Region collapsed from 152 000 ha of light

to severe defoliation in 1983, and declined to 200ha in each of the Cariboo and Nelson regions.

The major increases were in the Liard RiverValley in the Prince George Region where a newoutbreak of eastern spruce budworm C. fumifera-na lightly defoliated current year's needles ofvalley bottom alpine fir-spruce stands over 7 300ha between Km 790 and 863 on the Alaska High-way. Repeated severe defoliation in the areaduring outbreaks between 1957 and 1977 re-sulted in tree mortality, topkill and growth loss.

22

Light to moderate defoliation of current needlesby C. orae expanded to 2 700 ha in scatteredstands in the Kitimat and Wedeene river valleysin the western part of the Prince Rupert Region,up from 300 ha in 1983.

Very light current defoliation by C. biennis oc-curred over 1 500 ha of previously defoliated fir-spruce stands in the Bowron River Valley in thePrince George Region. In nearby Everett Creek,where 300 ha were lightly defoliated, a pathogenBeauveria bassiana and a polyhedrosis virus af-fected 16% and 7% of the larvae, respectively.This could reduce populations in the area in1985. About 200 ha of fir-spruce stands defoliat-ed in 1983 in the Willow and Big River drainages,north of Barkerville in the Cariboo Region, wereagain lightly defoliated. In the Nelson Region,populations in two stands in the West Kootenayarea, first recorded in 1983, lightly defoliated 200ha, and two localized infestations collapsed fromundetermined causes.

Two-year cycle budworm populations in theNass, Bell-Irving, Babine, Upper Skeena and Kis-piox river valleys in the Prince Rupert Regionalmost collapsed. Only 10% of the buds were in-fested compared to 50% in 1983, and larvae perbeating collection numbered less than 15 com-pared with up to 300 in 1983. Development wasdelayed by cool, wet conditions. The decline wasattributed in part to the high incidence of thepathogen B. bassiana in 1983.

Fall egg mass surveys indicate light defoliationcould occur in 1985 in the Kitimat area, and lightto moderate bud feeding by off-cycle budwormin the Willow and Bowron river drainages.

Western balsam bark beetleDryocoetes confusus

Mortality of mature alpine fir killed by the beetleand the associated fungus Ceratocystis dryocoetidisoccurred over 35 200 ha province-wide, up from3 000 ha in three regions in 1985. The apparentincrease was mostly in the Bulkley-MoriceT.S.A's in the Prince Rupert Region, and largelydue to aerial coverage of chronically infestedstands not routinely surveyed. Areas of recenttree mortality in widespread high elevationstands in the Cariboo, Kamloops, Nelson andPrince George regions averaged 2 500 ha, up

slightly from 1983.

Shoot blightsDelphinella spp.

Increased infections killed current years budsand severely discolored 1984 needles of most ageclasses of alpine fir from Prince George toMcLeod Lake. The most severely affected standswere from Bear Lake north to Carp Lake whereup to 80% of the 1984 buds were killed.

Balsam woolly aphidAdelges piceae

In response to the recent reporting of the aphidin Idaho, grand fir and alpine fir at 8 sites in theNelson Region adjacent to the Canada-USA bor-der were surveyed for the aphid but none wasfound. There has not been any significant changein the distribution of the pest in southwesternBritish Columbia.

Fir conewormDioryctria abietivorella

Increased populations lightly defoliated uppercrowns and leaders of most age classes of amabilisfir in mixed stands near Kelsey Bay, Schoen Lakeand Northwest Bay on Vancouver Island. Al-though the coneworm is usually associated withcone damage, shoots, foliage, stems, grafts andrust galls are mined periodically.

23

HEMLOCK PESTS

Western hemlock looperLambdina f lugubrosa

Despite a population collapse in the NelsonRegion, 13 350 ha of western hemlock and west-ern red cedar stands were lightly and moderatelydefoliated in 40 separate infestations in the Kam-loops and Cariboo regions, (see map 3).

Infestations in the Shuswap-Mabel lakes-Sey-mour River drainages in the Kamloops Regionalmost doubled to 8 000 ha of mainly lightdefoliation. Conspicuous light and moderatedefoliation over 5 250 ha occurred near QuesnelLake, following a two-year population buildup.Near the south end of Canoe Arm in the PrinceGeorge Region populations collapsed followingone year of severe defoliation over 850 ha. Aspredicted, outbreaks in previously defoliated oldgrowth western red cedar — western hemlockstands in the Revelstoke-Arrow lakes area in theNelson Region collapsed to only 100 ha in threelocations, down from 37 250 ha in 1983.

The one- to three-years of moderate to severedefoliation in mainly old growth stands has re-sulted in 2 to 3 m topkill at Blanket and Cranberrycreeks and Red Rock peninsula.

Moderate to severe defoliation is forecast in 1985near Quesnel Lake, based on the number of via-ble eggs (47) in 100 gram lichen samples. How-ever, the reduced number of eggs (range 1-15per sample) at four sites in the Kamloops andNelson regions will result in only trace or lightdefoliation. The decline is largely due to parasi-tism of overwintering eggs by the wasp, Tele-nomus sp., and infection of larvae by a nuclear po-lyhedrosis virus which affected 38% of the larvaeat Scotch Creek near Chase. Larval parasitism byDiptera and Hymenoptera was 51% at ScotchCreek and 10% at Quesnel Lake.

Western blackheaded budwormAcleris gloverana

More than 19 000 ha of old growth western hem-lock in 240 areas were lightly to moderately defo-liated with some severe pockets in the Revelstokeand Glacier National Park areas in the NelsonRegion (see map 4); up from 120 ha in 1983. Thepredicted increase followed a three-year buildupof blackheaded budworm populations in standspreviously defoliated by western hemlock looper.Moderate to severe defoliation occurred over 2500 ha in the Revelstoke-Glacier National Parkarea, where up to 40% of the crowns over 750 hawere severely defoliated at Bostock Creek. Popu-lations collapsed after two years of light defolia-tion of fir-spruce stands along Dewar Creek westof Kimberley.

Overwintering egg populations at five infestedstands in the Revelstoke area ranged from 1 to 19eggs (avg. 9) per 50-cm branch. Egg counts andlarge moth flights indicate continuing populationsin 1985. Increased blackheaded budworm larvalpopulations in stands previously defoliated byhemlock looper in the Kamloops Region indicatea potential for light defoliation in 1985.

Terminal crook diseaseColletotrichum acutatum

The pathogen was not found on western hemlockseedlings in three plantations near NorthwestBay on Vancouver Island, during the fourth in-spection since the stock was outplanted in 1981.Inspections were initiated following the discoveryof the introduced disease on seedlings in a lowermainland nursery.

Map 5

FOREST INSECTAND

DISEASE SURVEY

1984

BLUERIVER

Areas where current de-foliation and damagewas detected duringaerial surveys

1. Larch Sawfly2. Larch Budmoth3. Larch Casebearer4. Larch needle diseases

REVELSTOKE

LILLOOETT

LYTTON

KAMLOOPS

INVERMERE

NEWDENVER

KELOWNA

PRINCETONPENTICTON I ERNIE

NELSON

0 40kmI I I I I

TRAIL

•LAKE•

Canadian Forestry Service / Forest Insect and Disease Survey

25

LARCH PESTS

Larch casebearerColeophora laricella

Casebearer populations, delayed up to threeweeks by cool moist spring weather, still intensi-fied in most western larch stands in the NelsonRegion and to a lesser degree in adjacent areas ofthe Kamloops Region. Light to severe defoliationcovered 41 000 ha north of the United States-Canada border from Elko north to Kimberleyand west to Kootenay Lake (see map 5), downfrom 60 000 ha in 1983. The most severe defolia-tion was in the Cranbrook, Jaffray, Elko andKookanusa Lake areas. Light to moderate defoli-ation was common from Elko to Kimberley,Yahk to Creston, and light from Rock Creek toBridesville and Anarchist Mountain east ofOsoyoos. Small population increases north ofOsoyoos and east of Vernon lightly defoliatedsmall patches of western larch.

Although spring larval populations declined, as-sessments of overwintering populations at 11sites in the Nelson and Kamloops regions indi-cate light to severe defoliation of western larchstands will occur in 1985. Based on the numberof larvae per 100 fascicles (avg. 36, range 3-143),severe defoliation is forecast at AnarchistMountain, east of Osoyoos; moderate defoliationnear Cranbrook, Jaffray and east of OkanaganFalls, and light defoliation at Kookanusa Lake,Creston, Salmo and near Castlegar.

Pheromone-baited traps to monitor casebearerpopulations in 16 sites in the Nelson Region andfour in the Kamloops Region, mainly beyond theknown limits of casebearer infested stands at-tracted an average of 84 adults (range 0-3000+).Studies continue to determine the significance ofthe number of adults. Trap data indicates a north-ward migration within the host range, particularlyin the West Kootenay.

The larval parasite, Chrysocharis laricinellae wasreleased in two casebearer-infested stands in theEast Kootenay as part of a continuing biologicalcontrol program. Two hundred and forty maleand female adults were released near Fairmont

Hot Springs in mid-June and 537 near Cranbrookin mid-August. Introduced from Austria, theparasite has contributed to the decline of pre-viously high casebearer populations in the WestKootenay. Less than 4% of the pupae from 20sites in the Nelson and Kamloops regions wereaffected by parasites, the majority of which wereAgathis pumilla (47%) and C. laricinellae (28%).

Larch sawflyPristiphora erichsonii

Sawfly populations in western larch stands in theEast Kootenay area of the Nelson Region de-clined significantly in the third year ofinfestation. The area defoliated declined by athird to 3 000 ha in 20 areas of mainly lightdefoliation, with moderate to severe pocketsover 750 ha in the Elk River Valley west ofFernie to Morrissey, and in the Lost Dog Lakeand Skookumchuck Creek areas, (see map 5).Although consecutive years of severe defoliationwould probably result in growth loss, there hasnot been any evidence of branch or tree mortal-ity.

The predicted widespread decline in the Spar-wood, Fernie, and Elko areas was attributed toseveral natural control factors including parasi-tism and rodent predation of overwinteringpupae. A general population decline is expectedto occur again in 1985, based on the reducednumber (range 6 to 65, avg. 33) of overwinteringcocoon in 100 cm 2 duff samples from 3 infestedstands.

Defoliation of eastern larch stands 80 to 120 kmnorth of and near Watson Lake in the Yukonwere reported by Yukon Lands and Forests. Thiswas the first indication of increased sawfly popu-lations in the Territory since 1954.

Larch budmothZeiraphera improbana

Outbreaks in western larch stands in the NelsonRegion, particularly in the East Kootenay, de-

26

clined significantly to 1 100 ha. In 1984 only 10areas (see map 5) were moderately defoliated,compared to 6 600 ha in 36 areas in 1983. In theWest Kootenay budmoth populations were de-layed by about two weeks by cool moist condi-tions, but lightly to moderately defoliated 975 haof mature larch in the Blueberry-Paulson creeksarea west of Trail, for the first time. A secondyear of feeding severely defoliated 125 ha nearRossland. Unconfirmed aerial observations in-dicated light populations at Vance Creek north-east of Vernon where severe defoliation occurredover 500 ha in 1973-74. The cause of the declineof numerous small infestations in the East Koote-nay is not known but is similar to the rapid de-cline after one year of defoliation in the previousfour outbreaks since 1965.

Larch needle diseasesMeria Hypodermella laricis

Following wetter than normal conditions duringthe 1983 infection period, widespread infectionsof all age classes of western larch in the NelsonRegion and part of the Kamloops Region by bothdiseases (see map 5) were more severe and ex-tensive than in 1983. The more prevalent fungusaround Creston and in the western portions ofthe West Kootenay was M. laricis. From Brides-ville to Salmo and in the Kettle and Slocan rivervalleys up to 80% of the foliage on most larch,

particularly immature trees, was infected by bothfungi. Similar damage in stands up to 1 000 ha oc-curred from Crawford Bay to Yahk and Skoo-kumchuck in the East Kootenay.

Moderate to severe infections of H. laricis werewidespread in the host range east of the Okana-gan Valley, from Osoyoos to Anstey Arm onShuswap Lake.

Infection of mature trees was usually limited tothe lower half or third of the crown but wholecrowns of many immature trees were severelyinfected. Except for undetermined incrementloss and seedling mortality, tree recovery is usu-ally rapid unless subjected to repeated severeinfections.

European larch cankerLachnellula

Surveys for this canker disease during the pastfour years have been negative. Potentially dam-aging to all age classes of western, alpine and east-ern larch forests, it is currently limited to NewBrunswick, Nova Scotia and some eastern states.Although surveys were negative, two saph-rophytic fungi Lachnellula spp. were collected onwestern larch in southeastern British Columbiain 1984.

MULTIPLE HOST PESTS

Root and stem rots

Mortality of spruce, Douglas-fir and pine causedby root diseases such as Polyporus tomentosus, Ar-millari (mellea) ostoyae, Verticicladiella wageneriand Phellinus weirii is widespread throughout Brit-ish Columbia.

Infection of mature spruce by P. tomentosus in 28surveyed stands in the Prince George and north-

ern Prince Rupert regions and the Yukon rangedfrom 0 to 100% (avg. 35%). The highest averageincidence, (40-100% of the trees infected) oc-curred in nine stands from McLeod Lake east tothe Holmes River Valley, at Pine Pass (55%),and in Horseshoe Bay campsite in Kluane Nation-al Park in the Yukon where 33% of the sprucewere infected. In 13 stands in the Blackwater,Vanderhoof, and Fort St. James areas and 4stands near Cassiar 0-40% of the trees were

infected. Advanced decay was evident in recentlywindthrown mature spruce along access roadsand cut block fringes northwest of Ft. St. James.

An estimated 5% of the 13- to 24-year old sprucein nine plantations in the Kispiox River toBabine Lake area in the Prince Rupert Regionwere infected by P. tomentosus. Many of the mostseverely infected trees were adjacent to old in-fected spruce stumps. In older natural sprucestands, 7% of the trees in three stands were in-fected in the Morice River drainage and nearHouston. In the upper Bell-Irving valley lessthan 5% of the mature spruce in three standswere infected, and there was evidence of the dis-ease in one of three stands in the Kinskuch Riverdrainage north of Aiyansh.

A survey of the Sechelt Campground area inRoberts Creek Provincial Park in the VancouverRegion indicated 4% of the mature western hem-lock and Douglas-fir were killed or infected byroot, stem or heart rots. Phellinus root rot wasthe most prevalent on Douglas-fir, and Armilla-ria root rot on western hemlock.

P. tomentosus infected Engelmann spruce in twostands near Quesnel Lake in the Cariboo Region.In the Chilcotin and Nazko areas a high incidenceof red ring heart rot, Phellinus (Fomes) pini wasassociated with widespread windthrown lodge-pole pine.

Black army cutwormActebia fennica

Newly planted conifer seedlings were lightly toseverely defoliated by the cutworm in 6 of 27 re-cently burned sites in the Prince Rupert, PrinceGeorge and Cariboo regions (see map 4) downsignificantly from 200 000 seedlings damaged orkilled in 35 sites in 1983.

Despite the general decline, mainly from a nucle-ar polyhedrosis virus, larvae mined 30 to 3 5 % ofthe spruce buds on seedlings near Telkwa andHouston, and delayed planting at a third site.Elsewhere in the Prince Rupert Region, defolia-tion was limited to herbaceous ground cover,mainly fireweed.

Newly planted white spruce seedlings on recentlyburned areas near Davie and Weedon lakes in

the Prince George Region were severely defoli-ated. There was no evidence of larvae in morethan 30 plantations affected by the cutworm inthe region in 1983. The incidence of a nuclear po-lyhedrosis virus and parasitism of larvae andpupae reared by B.C.M.F. and submitted toPFRC from near Bear Lake, north of PrinceGeorge, was 66% and 23% respectively. The para-sites included Nowickia latigena (Tachinidae) andEutenyacra suturalis (Ichneumonidae).

Increased populations damaged up to 20% of thebuds of newly planted Engelmann spruce andDouglas-fir seedlings in two recently burnedsites near Mitchell Bay on Quesnel Lake in theCariboo Region. In an adjacent provenance trial25% of the Douglas-fir seedlings were lightlydefoliated but bud damage was minimal.

Larval feeding was limited to herbaceous groundcover at four sites in the North Thompson Riverdrainage in the Kamloops Region.

More than 135 baited traps at 39 sites in three re-gions where cutworm larvae were active, attract-ed an average of 10 adults per trap (range 1 to39). The highest numbers per trap, 39, were atWeedon Lake in the Prince George Region. Be-tween Smithers and Burns Lake moths weretrapped in 31 sites with the highest concentra-tions near Smithers Landing. Based on the num-ber of pupae (0.4 to 11) per sample and adults intraps, populations could occur in most recentlyburned sites in the Prince Rupert Region sche-duled for 1985 planting. Only single moths weretrapped in each of three areas in the NorthThompson River Valley. The significance of thenumbers of moths per trap, beyond identifyingtheir presence continues to be studied.

Rodents

Tree mortality, topkill and severe debarking oflodgepole pine and western hemlock by rodentsincluding porcupines, voles and snowshoe haresincreased in the Nelson, Prince Rupert, Kam-loops and Vancouver regions.

Porcupines killed 15% and debarked 35% of thelodgepole pine regeneration in numerous smallpatches and top-killed 3% of the trees in a 50 hasite southwest of Cranbrook. At Hanna Creeknear Rossland up to 50% of the intermediate

28

western larch were top-killed. West of Terrace atDasque Creek, 20% of the 10- to 30-year oldwestern hemlock trees and 40% of the terminalswere killed over 35 ha. Similar incidences of por-cupine debarking have occurred periodically inspruce regeneration in parts of the Prince RupertRegion since 1976. Damage to single scatteredconifers increased generally throughout thePrince Rupert Region.

In the Nelson Region, debarking of dwarf mistle-toe-infected lodgepole pine branches by squirrelsat Dewar Creek affected 90% of the trees over 30ha.

Feeding attributed to snowshoe hares killed 5%and caused partial basal girdling of 95% of theyoung spaced lodgepole pine over 20 ha at SkullCreek northwest of Kamloops.

Increased vole populations (up to 50 per ha)debarked 40 to 70% of the stems of 5- to 10-yearold Douglas-fir in plantations on Texada Island.

creased infestations by cone and seed pests whichseverely affected the light scattered Douglas-firand white spruce cone crops in interior stands.

Most of the Douglas-fir cones (avg. 94%, range78 to 100%) in four areas in the East Kootenaywere infested and 26%, (range 12 to 38%) in sixstands in the West Kootenay of the NelsonRegion. The major pest was a cone moth, Barbaracolfaxiana with lesser amounts of a cone gallmidge, Contarinia oregonensis, a cone scalemidge, C. washingtonensis a cone moth, Dioryctriaabietivorella and a seed chalcid, Megastigmusspermatotrophus.

A cone disease, Sirococcus strobilinus infected65% of the very light scattered white sprucecones at Chetwynd in the Prince George Region.Inland spruce cone rust, Chrysomyxa pirolata in-fected 4% of the Engelmann spruce cones nearNakusp in the Nelson Region and 25% of thewhite spruce cones at the Skimikin seed orchardnear Salmon Arm.

Climatic injury

Frost during bud flush in late May killed up to70% of the terminal and lateral buds of immatureand seedling conifers in localized areas in thePrince George, Prince Rupert, Kamloops andVancouver regions. Terminal and lateral budmortality averaged 2% and 16% respectively, on10- to 16-year old spruce in five plantations inthe Kispiox-Babine Lake area in the PrinceRupert Region. Up to 70% of the buds werekilled on most spruce in a natural stand atTumuch Lake and near Pilot Mountain in thePrince George Region. Elsewhere about 5% ofthe lateral buds of mature planted and naturalDouglas-fir were killed in localized stands in theFraser Canyon, east of Hope, and on BowenIsland. Approximately 50% of the buds onmature Douglas-fir were killed in two stands nearBarnes Lake near Ashcroft. At Surrey someDouglas-fir, Sitka spruce and western red cedarseedlings were severely affected by late frost.

Cone and seed pests

Cone crops in coastal and interior stands weregreatly reduced from 1983. This resulted in in-

Acid rain monitoring

Unprecedented tree mortality and foliar damagein Europe and some locations in eastern NorthAmerica has increased the attention on acid rainand airborne pollutants. The relationships be-tween acid rain and frost damage have not beenclearly demonstrated. Direct action of the pollu-tants on the cuticle of the foliage may occur, per-haps influencing subsequent frost damage orinsect and disease attacks. Slight changes in soilpH may affect mycorrhizae, increase solubility oftoxic elements or leach necessary elements fromthe soil.

With rainfalls as low as pH 4.6 being recordedwhen storm fronts move into southwestern B.C.through the Puget Sound, and with the existenceof some sensitive soils of low buffering capacity,the potential of forest damage in western NorthAmerica is also recognized.

To obtain baseline knowledge of the concentra-tions of foliar and soil elements, foliar conditionand tree growth, and to detect and monitor possi-ble changes, a nationally standardized series offorest plots are being established. These consti-tute the CFS-FIDS Acid Rain National EarlyWarning System (ARNEWS). To date, three

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such permanent plots have been established inBritish Columbia; near Shawnigan Lake, on Salt-spring Island and on the UBC Research Forest.These areas were selected in part because of theavailability of other related information such astree growth, water quality and soil chemistry.Additional plots will be established in 1985 and1986.

To obtain a more immediate assessment of thecondition of the forest in B.C., FIDS rangersmade additional observations at 417 permanentsample sites (PSS) throughout the province. Par-ticular attention was directed to symptomsreported to be typical of acid rain damage inGermany, namely: casting of green or uncharac-teristically shaped leaves, premature discolora-tion and shedding of needles, unexplained die-back, early flattening of tree crowns ("storksnesting abrupt decline in foliage or annualring growth, etc. Site assessments were distribut-ed among the soil sensitivity zones with 19% low,17% moderate, and 64% high. Site distributionby wet sulphate deposition zone was 17% with20-30 kg/ha/yr, 17% with 10-20 level and 66%less than 10.

Trees were healthy in 80% of the PSSs. In 20% ofthe sites, mainly in the West Kootenay, trees hadthin crowns (frequently due to current or recentinsect feeding or needle casts) or flat tops usuallyassociated with stand maturity. Some level ofinsect or disease activity was recorded on 40% ofthe sites. At least 20 tree species and numerousground cover species were observed. Needle re-tention averaged three to five years, generallydepending on species. Although long term or in-direct effects may be accumulating, all obviousdamage encountered could be accounted for bycurrent or previous pest conditions.

Stand improvement assessments

In support of the Environment 2000 projects ad-ministered by the C.F.S., pest conditions were as-sessed at 17 sites in the Kamloops, Nelson,Prince Rupert and Vancouver regions.

Major pest problems found at sites near Enderby,Golden and Powell River were all root rots.

A brown cubical butt rot, Polyporus sericeomollisinfected 90% of the 40-year-old western red

cedar on about 6 ha of a 29 ha spaced, mixedstand near Enderby. More than 50% of the heart-wood was decayed at the butt level of most trees.Removal of infected standing cedar and replace-ment with other species including lodgepolepine, was recommended.

About 50% of the mature Douglas-fir in mixedstands in the Blackwater area north of Goldenwere infected by Armillaria root rot, Armillaria(mellea) ostoyae, first identified as a problem inthe area in 1979. Western larch, which is less sus-ceptible to A. mellea infection, has now beenplanted in the infected stands.

Lightly infected by Phellinus weirii, small pocketsof 60-year-old Douglas-fir were evident in mixedconifer stands adjacent to an access improvementproject near Powell River. Some blowdown mayoccur.

Pests of less or little concern were observed at 9sites in the Kamloops, Nelson, Prince Rupertand Vancouver regions. Light infections of west-ern hemlock dwarf mistletoe, Arceuthobium tsu-gense were culled from 35 ha in a spaced mixedstand near Comox, successfully controlling infec-tion. Natural stands near an access improvementproject near Powell River were lightly infected bythe mistletoe. Sitka spruce weevil, Pissodes strobiin 2% of the leaders of 12- to 15-year-old trees intwo spaced stands near Kitimat and Terracecould intensify and should be monitored. A rootcollar weevil, Hylobius warreni in less than 1% ofthe 7-year-old spaced lodgepole pine stand nearGolden could increase following the spacing. Apruning control program of lodgepole pine dwarfmistletoe, Arceuthobium americanum was satisfac-torily initiated near Merritt. Pine needle dis-eases, Lophodermella spp. moderately infected upto 30% of the 1983 needles of most residuallodgepole pine in two spaced stands near Golden.About 2% of the branches of residual 5-year-oldlodgepole pine in a 30-ha spaced stand nearCanal Flats were infected by western gall rust,Endocronartium harknessii which could have beenremoved during spacing. In an adjacent spacedmixed stand, Rhabdocline needle disease Rhab-docline pseudotsugae infected up to 40% of the1983 needles on most trees. Swiss needle cast,Phaeocryptopus gaeumanii lightly infected olderneedles on 10% of the spaced immature Douglas-fir in a mixed 35-ha stand near Comox. Foliardiseases, while decreasing growth, should not be

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serious unless repeated and severe over severalyears.

The majority of the implemented stand treat-ments were generally satisfactory at the time of

examination. However, increased recognition offorest pests, particularly perennial diseases inyoung stands scheduled for spacing, could pre-vent spread of infection and enhance the qualityof residual trees.

DECIDUOUS AND ORNAMENTAL TREE PESTS

Tent caterpillarsMalacosoma disstria, M. californicum pluviale

Forest tent caterpillar, M. disstria, populationsdefoliated 30 700 ha of trembling aspen stands inthe Prince George, Prince Rupert and parts ofthe Nelson Region, but collapsed in the CaribooRegion. Western tent caterpillar M. c. pluviale in-festations north of Terrace declined to 900 ha.Localized colonies were widespread in the FraserValley and south and east coastal VancouverIsland.

Defoliation by forest tent caterpillar was mainlymoderate to severe over 29 700 ha in the SalmonRiver Valley and Peace River in the PrinceGeorge Region for the second consecutive year.Mainly light to moderate defoliation with somesevere pockets over 1 000 ha occurred nearMoricetown, Hazelton and Kitwanga in thePrince Rupert Region. Scattered aspen and cot-tonwood groves and other trees and shrubs werelightly defoliated around Trail in the NelsonRegion.

After four consecutive years of defoliation in theBell-Irving River and Meziadin Lake valleys inthe Prince Rupert Region, western tent caterpil-lar populations collapsed. The collapse is attribut-ed to natural control factors, including parasites.

For the fourth consecutive year, colonies of west-ern tent caterpillar severely defoliated deciduoustrees and shrubs in widely scattered pockets inthe Fraser Valley and southern and eastern coast-al areas of Vancouver Island. Little change is ex-pected in 1985.

Egg masses in recently defoliated stands in thePrince Rupert and Prince George regions indicatecontinuing moderate and severe defoliation in1985.

Poplar shoot blights

Trembling aspen and black cottonwood stands,mainly in the Prince Rupert and Prince Georgeregions and to a lesser degree in the Nelson andKamloops regions, were moderately to severelyinfected by the shoot blights Venturia macularisand V. populina. Moist spring weather favoredinfection. Dead shoots and leaves were partic-ularly common on aspen in groves in the NassRiver Valley from Kitwanga to Cranberry Junc-tion. More than half of the stands betweenEndako and Hazelton and in the Nass, Kispiox,Babine and Skeena river valleys were lightly tomoderately infected, with numerous 1- to 10-hapatches where entire crowns were severelyinfected. Conditions were similar and commonin the Peace River and Vanderhoof to FraserLake areas in the Prince George Region.

A second year of infection in the West Kootenaycaused dieback of the upper crowns in 15% of theaspen from Shelter Bay to Revelstoke. Severe in-fection of up to 50% of the trees, usually in 1-haor smaller groves, and a few up to 200 ha, oc-curred in the New Denver-Zincton area. In theEast Kootenay up to 90% of the aspen standswere severely infected in the Sparwood-Flatheadand Revelstoke-Golden areas. Shoot mortalitywas common and severe in black cottonwoodgroves in the Creston and Elko areas. Moderately

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to severely infected groves were widespread inthe Kamloops Region particularly west of LittleFort to Bridge Lake and in the Adams RiverValley.

A birch leaf minerLyonetia saliciella

Leafminer populations in previously defoliatedwestern white birch stands in parts of the PrinceGeorge and Nelson regions declined. Larvalmining lightly discolored most birch stands inthe McBride-Valemont area and severely discol-ored small localized immature groves east ofTeté Jeune Cache to Mt. Robson. Reduced popu-lations lightly to moderately discolored scatteredbirch stands in the Golden area for the seventhconsecutive year. there was no evidence ofbranch or tree mortality in affected areas andmost trees refoliated in late summer.

A birch leaf skeletonizer, Bucculatrix canadensi-sella in the Trail area collapsed after two consecu-tive years of severe defoliation.

Striped alder sawflyHemichroa crocea

For the second consecutive year, sawfly popula-tions increased and defoliated widely distributedareas of red alder in the Queen Charlotte Islandsand coastal areas of the Prince Rupert Region.Mostly light to moderate defoliation, with pock-ets of severe defoliation up to 5 ha, was commonfrom Queen Charlotte City to Masset on GrahamIsland and occurred sporadically between Kitimatand Prince Rupert. Similar levels of defoliationare expected to continue in 1985.

Gypsy mothLymantria dispar

Larvae were recorded in the Courtenay area inMay-June during egg-mass surveys by Agricul-ture Canada and 25 adults were caught in 12 phe-romone-baited traps in August-October. How-ever, none were found in 188 traps in 117 forest-ed recreational areas throughout the provincemonitored by the Forest Insect and Diseasesurvey in cooperation with Agriculture Canada.Two adults were trapped in Vancouver near the

P.N.E., one adult at Cultus Lake; four adults and11 egg masses were found near Chilliwack, andone adult was trapped at Adams River, east ofKamloops.

Since first recorded in British Columbia in 1976in the Lower Mainland, adults and egg masseswere found in the Langley area, and for the firsttime on Vancouver Island in 1983 near Courte-nay. Defoliation has not occurred and popula-tions have not become established. Egg massremoval and some localized treatments werecompleted.

Although ornamental and urban trees could beseverely defoliated as populations becomeestablished, the major forestry concern wouldlikely be quarantine restrictions such as those re-cently implemented in active Gypsy moth areasin Oregon.

Egg mass surveys and pheromone trapping pro-grams in cooperation with Agriculture Canadawill continue in 1985.

Satin mothLeucoma salicis

For the second consecutive year trembling aspenand black cottonwood groves were severely defo-liated in parts of the Nelson and Kamloopsregions. One- to five-ha groves were moderatelyto severely defoliated between Rock Creek andBridesville, near Trail, New Denver, SummitLake and Moyie in the Nelson Region and nearTulameen in the Kamloops Region but popula-tions collapsed near Carpenter Lake. Satin mothlarvae were common on conifer seedlings of theB.C. Ministry of Forests nursery at Harrop, eastof Nelson. However, there was no evidence ofdamage to the seedlings. The larvae emergedfrom eggs laid by moths, which were attracted inlarge numbers by lights at the nursery site inJuly. Since the moth was first recorded in theNelson Region in 1963, only deciduous hostshave been defoliated.

Western oak looperLambdina f somniaria

Defoliation of mature Garry oak was light in anecological reserve on Saltspring Island. After 5

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successive years of defoliation, most trees stillappear reasonably vigorous and have recoveredsuccessfully. A small number of previously defo-liated mature Douglas-fir have also recoveredand Douglas-fir bark beetle is no longer a threat.Vigorous but declining numbers of larvae, show-ing little evidence of natural control agents, indi-cate populations will continue in 1985 but at re-duced levels.

Winter mothOperophtera brumata

For the fourteenth consecutive year, light tosevere defoliation of deciduous trees and shrubswas widespread in the Greater Victoria area, Saa-nich Peninsula and Western Communities, andseverely affected the aesthetic value of urbantrees. In the Duncan area where the pest was col-lected for the first time in 1983, populations in-creased and expanded lightly defoliating Garryoak and maple and moderately defoliated nearbyfruit trees. Larvae were collected for the firsttime on Saltspring Island in a Garry oak stand,and two male adults were caught in a pheromone-baited trap at Nanaimo. It is not resident in theLower Mainland or Fraser Valley.

The introduced larval parasite Cyzenis albicans re-leased during 1979-82 increased significantly in1984 affecting 44% (range 19-77%) of the wintermoth populations at 33 sites in the Greater Victo-ria area and one site at Duncan. Based on x-rayexamination of material from one location, about

2% appeared to be parasitized by Agryponflaveolatum.Other parasites affected about 2% of thepopulation.

Dogwood leaf blotch, (Anthracnose)Gloeosporium sp.

The incidence of infection of dogwood trees inthe east coastal area of Vancouver Island and theVancouver Mainland area declined slightly toabout the 1982 level. Foliar discoloration onsingle trees and small groups of up to 10 treeswas light to moderate at Peace Arch ProvincialPark, Alouette Lake, in Vancouver and WestVancouver, and from Victoria to Nanaimo.Flower production was reduced in 1984, but twigor branch dieback, which could result fromrepeated infections, has not yet been observed.

Cypress tip mothArgyresthia sp.

Severe discoloration and branch tip and tree mor-tality of ornamental cypress trees and shrubs oc-curred for the second consecutive year in theGreater Victoria, Duncan, Nanaimo, Port Al-berni and Campbell River areas. High over-wintering survival rates and population buildupscontributed to the increased damage. Precludingadverse climatic conditions in 1984-85, severediscoloration and some tree mortality could berepeated in 1985. Native conifers have not beenaffected.