Methods used to establish permanent plots in precommercially thinned and unthinned stands to monitor root disease development are described. Plots were established in 22 Armillaria-infested stands in northern Idaho and western Montana. The proportion of trees dead and infected was significantly higher for planted than for natural regeneration at the time of plot establishment

Byler, James W.

Hall, L. D.

Stewart, C. A.

United States. Forest Service. Northern Region. State & Private Forestry

Undetermined

ScholarsArchive@OSU

ESTABLISHMENT REPORT: PERMANENT PLOTS TO EVALUATE THE EFFECTSOF ARMILLARIA ROOT DISEASE IN PRECOMMERCIALLY THINNED STANDSbyJ. W. Byler, C. A. Stewart and L. D. HalliBEaTEilaMethods used to establish permanent plots in precommercially thinned andunthinned stands to monitor root disease development are described. Plots wereestablished in 22 Armillaria-infested stands in northern Idaho and westernMontana. The proportion of trees dead and infected was significantly higherfor planted than for natural regeneration at the time of plot establishment.INTRODUCTIONArmillaria root disease, caused by Armillaria sp. 2 , is common in the forestsof Montana and Idaho (James, et al. 1984), Oregon and Washington (Filip 1977,Shaw & Roth 1978), and British Columbia (Morrison 1981). Root disease centersof tree mortality and stands with scattered tree killing occupy a sizableproportion of the commercial forest land in sane Region 1 National Forests(James et al. 1984), and Armillaria is associated with much of this treemortality. Surveys in merchantable stands indicate that cumulative losses overa rotation can be significant.Armillaria root disease is also common in plantations and young growth stands.It is evident in these stands as scattered killing of individual trees andsmall groups, often near stumps that serve as food bases for the pathogen.It is generally assumed that the pathogen will adversely affect the growth anddevelopment of these young-growth stands. However, the effects have not beenquantified. For this reason, permanent plots have been established in 22diseased young-growth stands on five National Forests in Region 1 to monitorthe effects of root diseases. These root disease evaluation plots supplementthe Region's growth and yield permanent plots, sane of which also have rootdisease.1J. W. Byler is Supervisory Pathologist in Cooperative Forestry and PestManagement, Missoula, MT; C. A. Stewart is a Forester on the Missoula RangerDistrict, Missoula, MT; L. D. Hall is a Biological Technician in CooperativeForestry and Pest Management, Missoula, MT.2Armillaria  mellea has been assumed to be the cause of Armillaria rootdisease in the northern Rocky Mountains and Intermountain West. However,recent authors in Canada and the western United States indicate the cause maybe Armillaria ostoyae.Cur initial hypotheses, based on Morrison (1981) and observations in thisRegion, are as follows. Above normal rates of tree mortality will take placein all conifer species until about age 25-30, when rates for western larch andthe pines will decrease. Rates for Douglas-fir and true firs will remainhigh. The long-term effect of disease will be to favor pines and larch wherepresent, and to reduce stocking. Plots with little pine and larch will developinto nonstocked or poorly stocked root disease centers. Planted trees will bekilled at higher rates than natural regeneration, especially when less than 30years of age. Precai,nercial thinning that leaves Douglas-fir, true firs,planted pines, or planted larch combined with high mortality rates may lead toan understocked condition for a time.The goal of this project is to evaluate the long-term effects of Armillariaroot disease on stand growth and yield. Specifically the objectives are to:1. Measure mortality rates expressed as average number of trees killedper acre per year caused by the disease,2. Determine the effects of tree species, tree age, regeneration method(planting vs. natural) and treatment (precammercial thinning) onmortality rate, and,3. Measure the long-term effects of Armillaria-caused mortality on standspecies composition, stocking and volume.MEW=The root disease plots were established during the 1983 and 1984 field seasonsto supplement the Region's timber growth and yield permanent plots. Timbergrowth and yield plots have been established throughout the Region during thepast few years. Clusters of three 1/20-acre plots are randomly placed withinselected stands (Timber Management Handbook 2409.21--12).Stands were selected for root disease evaluation plots as follows. A list ofcandidate stands was obtained from Forest and District foresters andsilviculturists, giving priority to stands with timber growth and yield plots.These stands were examined for root disease and selected or rejected based onthe following stand selection criteria:1. Armillaria root disease was sufficiently present to allow placement ofcontrol and treatment plots in the same stand.2. The stand was suitable in size and stocking to be precommerciallythinned.3. A mix of tree species was present.4. The final plot list would include stands well distributed over the sixtimber-producing Forests with significant Armillaria mortality.In all, 22 stands were selected, most of which met all of the above criteria.Four of these also contained timber growth and yield plots. Timber growth andyield plots in 23 additional stands were examined for root disease. Ten ofthese stands had Armillaria-associated tree mortality.In 1983, stands selected for sampling were surveyed for root disease beforepermanent plots were established. Random plots were used to evaluate the standcondition (T/A by species) and root disease condition (percent plots affectedand percent of trees dead or declining). This survey was dropped during thesecond year because of time constraints.Plots were established according to the methods described in the study planusing the R-1 stand exam forms and procedures for permanent plot datacollection. The plots were one-twentieth acre in size. Two three-plotclusters were established in each stand. One plot was thinned, and one wasleft unthinned.Leave trees were selected using R-1 guidelines and practices. All plot treeswere examined for root disease (before thinning on the thinned plots). Alltrees were tagged (after thinning on thinned plots).Plot locations were not selected randomly, but placed in preselected portionsof the stand that met the following criteria:1. Armillaria root disease was present.2. Adequate stocking was present so that future mortality could bemonitored.4,		 The goal was to make plots representative of the diseased portion of thestand. Thirty-five mm color slides were taken from plot center at the plotsestablished in 1984.Data from the 22 diseased stands, but not the additional TM stands, weresummarized using INDIDS (Bousfield 1980). Analysis of variance and t-testswere run on the arc sine of the percentage of trees per plot unaffected by rootdisease. llikey's Multiple Range Test was used to test significance ofIP		 regeneration method, tree species, tree size, and habitat type on percent oftrees killed or symptcmatic.The intent is to reexamine the plots at intervals of 5 years following aninitial reexamination after 2 years. Diameter at breast height, root diseaserating, and tree condition (live or dead) will be recorded for each tree onIP		 each exam. Mortality rates will be calculated for different stands,treatments, and tree species.Appendix A is a summary of the surveyed stands and their locations.RESULTSIPStand summaries were made and statistics were calculated to describe rootdisease conditions in the stands at the time of plot establishment. Mostobjectives of the project can only be met following a minimum of 1 to 2reexaminations of the plots, made 2-12 years after plot establishment.Following are summaries of plots located in disease portions of 22IP	precommercial stands.aARMILLARIA DAMAGE. Armillaria was the only root pathogen detected on mostplots, although a thorough examination for other pathogens was not made.Figure 1 illustrates the current amount of mortality on the permanent plotswith root disease. In most stands, about 5 to 10 percent of the plot trees peracre were dead. We estimate this mortality occurred over approximately a5-year period. If so, the average annual mortality rate on the diseased plotsis between 1 and 2 percent.A substantial proportion of the trees on disease plots was also infected andshowing symptoms of disease (figure 1). Symptoms included thin and/ordiscolored foliage, and resin flow at the root collar. Overall, aboutone-third fewer trees were symptomatic than were dead at the time of plotestablishment. Appendix B summarizes the numbers and percentages of the plottrees in each stand that were symptomatic (infected) and the number killed.FACTORS AFFECTING MORTALITY. Data from diseased permanent plots in the 22stands were analyzed to determine whether the percent of dead and infectedtrees was related to regeneration methods, tree species, tree size, or habitattype series.A significantly higher proportion of planted trees was affected by Armillariaroot qisease than was natural regeneration. The average percentage of plantedtrees of all species that were dead or symptomatic was 26.6. The averagefor natural regeneration was 8.7 percent. The difference was significant atthe 99 percent level. The relationship held for Douglas-fir and true firsanalyzed as a group (planted 23.1, natural 10.7); and for western larch,ponderosa pine, white pine, and lodgepole pine group (planted 24.4, natural 	 gi7.5).Tree species were also grouped to test the hypothesis that Douglas-fir and true 11-1firs (grand fir and subalpine fir) were more damaged by Armillaria than werewestern larch and pines (ponderosa pine, lodgepole pine, western white pine).While a higher percentage of firs was affected than larch and pines, 12.8compared with 7.0, the difference was not significant.An attempt was made to determine whether infected trees differed in size(d.b.h.) from unaffected ones. While the mean diameter of diseased trees (2.3inches) was somewhat larger than the average (1.5 inches), the difference wasnot statistically significant.Plot data were also summarized by habitat type series, Douglas-fir, grand fir,cedar/hemlock, and subalpine fir. No difference was apparent in the percentageof trees affected by Armillaria in different series. Of the 41 clustersexamined, the representation by habitat type was Douglas-fir series 11, grandfir series 5, cedar/hemlock series 5, and subalpine fir series 11.3When both natural regeneration and planted trees of the same species were	 4111present in a stand, all trees of that species were included in the "planted"category because of difficulty in distinguishing planted individuals fromnaturals.-4-DISCUSSIONThe most significant result so far is that about three times as many plantedtrees were affected by Armillaria as were naturally regenerated trees. Theincreased susceptibility of planted trees has been noted by others (Shaw & Roth1978). The reason for this is not known. The difference may be due to amismatch of planting stock to the site (seed source), poor root growth due toimproper planting, or planting in the shade of stumps, a practice that mayincrease the likelihood of infection.Our inability to demonstrate a difference in species susceptibility was alsonot surprising. All conifer species are susceptible at a young age (Morrison1981). Most of our stands were less than 30 years of age.We currently recommend regenerating Armillaria-infected areas with westernlarch or pine rather than Douglas-fir and true firs, and we don't believe it isadvisable to change that recommendation. We anticipate that futureexaminations will show a relative decrease in pine and larch mortality.Permanent plots were subjectively placed in root-diseased portions of thestand. An attempt was made to determine whether these plots wererepresentative of diseased portions of the stand. Summaries were made of plotdata from six stands surveyed in 1983, stands that had a three-plot cluster ina portion not to be thinned, and diseased plots on transects of randomly placedplots to sample the stands. The percentage of affected trees on the randanplots was similar to that fran permanent plot clusters located in diseasedportions of the stand (table 1).We conclude that the permanent plots can be considered representative of thoserandanly placed plots that have diseased trees. An approximation of stand losscan be projected from the mean loss on permanent plots multiplied by theproportion of randan plots that are diseased.Large-scale black-and-white photographs that predated harvest were availablefor many of the stands. These were examined to determine whether root diseasecenters were visible in the previous stands. No centers were visible, and weconcluded that most of our plots fell in locations that were not centers.111n•-6-0••Table 1.—A comparison of the percentage of trees affected by Armillaria ondifferent plot types in the same stands.Percent dead or infected 2 % plots with3Stand Control Treatment	 Random 	 root disease379 36 15 19 47347 7 11 12 35663 22 - 18 9847 8 3 7 36833 15 14 15 50848 30 10 25 63'Data from 3-plot clusters collected before plot wasthinned.2Randomly selected 1/10-acre plots along transectsthrough the stand. Data summaries are for plots withinfected trees only.3Percent of randan plots that had at least oneArmillaria-infected or killed tree.LITERATURE CITEDBousfield, W. E. 1980. R-1 forest insect and disease damage survey system.Forest Insect and Disease Management Rept. 79-2.Filip, G. M. 1977. An Armillaria epiphytotic on the Winema National Forest,Oregon. Plant Dis. Reptr. 61: 708-711.James, R. L., C. A. Stewart, and R. E. Williams. 1984. Estimating rootdisease losses in northern Rocky Mountain national forests. Can. J. For.Res. 14: 652-665.Morrison, D. J. 1981. Armillaria root disease; a guide to disease diagnosis,development and management in British Columbia. 15 p.Shaw, G. C., III and L. F. Roth. 1978. Control of Armillaria root rot inmanaged coniferous forests. A literature review. European J. of For.Path. 8(3): 163-174.•00•APPENDIX A•• STANDS WITH PERMANENT PLOTS:ROOT DISEASE AND/OR TM GROWTH AND YIELDThe following table lists 45 stands on six National Forests that have eithertimber growth and yield plots or root disease evaluation plots, or both.All stands were checked for root disease during 1983 and 1984. Of these, 32stands are of precommercial size and contain permanent plots with Armillariaroot disease. Twenty-two have root disease plots that were located indiseased portions of the stand, and 10 others have randomly selected TMgrowth and yield plots on which Armillaria is present. Two stands hadArmillaria, but plot trees have not been examined for root disease. All 34should be reexamined for root disease mortality in the reinspection years.Additional growth and yield plots may have Armillaria, but were notexamined.•S••••-8-APFE/V1X ASDKs W1111 LERCNENT PIDIS:Fox DISEASE PNI/CR '1M GRIM RD YIELDa Att	 "Jr;	 •FbotHon type/ diazese..-; it	 •;k11_-	 see.	 •ape plotsti zrate ofawr Pierce	 10945-011 Brady Cr.	 1 Arrnillaria 1987109-C17-004 Lok Cr.	 1 are 1988Icchsa	 520-07-006 W. F. fete Kirg Cr. 1 Armillaria x 1988520-08-011 Jungle Pt.	 1 Annillaria/ x 1988 OzarercialAncsusFelly Cr.	 414-02-004 Crier Cr.	 2 Nme x 1988414-01-001 D33Epticn	 2 /tre x 1987413-03-004 Nine x 1988hit ti 	 Cr.	 2313-03-036 Inispe*rit Ridge	 2 N3V x 1988Palace	 253-03-005 ast Danis	 2 lhaeolus x 1986 QmrercialHID Spouted Peer 446-06-001 Baptiste Cr. Annillaria x 1986MP' Fen 	 346-01-001 Laverne Sale	 1 Annillaria/ x 1988301-08-013 &to Ptak	 2MenialsAMLillaria x 1989 •Sandpoint	 663-02-002 N3CCrt Arm Maria/hires1985Priest liver 847-02-002 Itar High Ridge Arraillaria x 1986833-03-001. inert P1acktail Ann Maria x 1986847-02-002 Sgmq Valley Atmillaria x 1986Bcrners Ferry 731-04-035 ctrcer Cr. Annillaria 1986Wallace	 199-04-016 lharrscri Pass	 2 Anuillaria x 1989N9-04-018 ilharracn Pass	 1 x 1989152 51 = 24 plots re-gemined2 = Stand %elk thrzugh3 = Ric•s—9—• •if•••11APEEEDIX A, ant.41;11,;:41 I 'zrr. IPFtotBan typal disease4101	 •Type plotsIljDate aE114:12A±113. 0.11M1.7401,..Cabinet 704-06-015 S. F. Bull R. 1 Arrnillaria x 19897C2-01-003 Deed Fosse x 1986703-07-0Ea Green (Ugh Arrnillaria x 1986Ebrtire 342-03-001 Itul Cc. Annillaria x 1986Rexford 119-03-004 Barer Et. Anaillaria x 1986Fisher R. 607-01-061 Five Mile Arrnillaria x 1986E14-04-005 &MUT RI Annillaria x 1986KID Miazcula 347-06-033 Gilbert Cr. Aerrillaria x 19E5379-01-034 Verde Fam Annillaria 1985Mire Mile 418-04-010 ltdc Cr. Amillaria x x 1985acerior 765-01-018 First Cc. Arrnillaria x x? 1986763-01-007 9axrd Cr. Annillaria x 1986743-01-001 Sunset Cr. Annillaria x 1986Thcrrpacn &31-01-019 Beatrice Cr. Arrnillaria x 3906Falls 577-03-010 Ctrrrtest Cr. 1 Annillaria x 1990/CCP Solway 716-01-104 Big Cedar Cr. /malaria x x 1986'702-02-006 Nifbatex Cc. Armillaria x 19861 	 River 509-04-002 Loan Cr. 1966Cleanfater 422-02-065 Ziain Cbbins 1 Am:Maria x 1988421-02-027 1 bIlgate Scnre 1 Armillaria/othersx 1986409-01-021 B1	 i1 Butte 2 Armillaria ? x 1988 Oznnercial303-01-008 angle Sc. 1 Nae x 1989303-01-003 Stalls Lick 1 Atrathria x 1988420-03-007 Clam 2 Nzre x 1987422-01-004 Cold Sakes 1 Annillaria x 1989-1 0-Appendix B.--A summary of Armillaria infection and mortality on infestedpermanent plots.Unit name Stand no. TreatmentSpecies totalaual_T/AInfected	 MortalityT/A % T/A	 %Squaw Valley Flats 848-01-003 C 93.3 19.7 46.7 9.9 473.3West Blacktail 833-03-001 C 6.7 1.4 66.7 13.7 486.7Rear High Bridge 847-02-002 C 46.7 2.6 86.7 4.9 1786.7Rock Creek 418-04-010 C 26.7 1.9 126.7 8.8 1433.3Verde Face 379-01-034 C 43.3 5.7 500.0 30.4 1646.7Gilbert Creek 347-06-033 C 6.7 0.3 133.3 6.2 2140.0Copper Creek 731-04-015 C 246.7 42.0 113.3 19.3 586.7Loon Creek 509-04-002 C 100.0 7.5 73.3 5.5 1326.7Helmer Mtn. 119-03-004 C 20.0 1.9 93.3 8.8 1060.0Five Mile Creek 607-01-061 C 326.7 8.2 246.7 6.2 3960.0 41McRillop Road 624-04-005 C 66.7 3.3 73.3 3.7 2006.7 'Dead Horse Creek 702-01-003 C 140.0 4.7 173.3 5.8 2993.3Green Gulch 730-07-001 C 40.0 10.2 53.3 13.6 393.3First Creek 765-01-018 C 26.7 6.1 33.3 7.6 440.0Beatrise 831-01-019 C 206.7 10.6 500.0 25.7 1946.7Big Cedar Creek 716-01-104 C 26.7 10.8 33.3 13.5 246.7*Big Cedar Creek 716-01-104 C #2 6.7 2.0 26.7 8.2 327Sunset Creek 743-01-001 C 20.0 4.5 33.3 7.6 440.0Baptiste 446.06-001 C 233.3 8.2 166.7 5.9 2840.0Second Creek 764-01-047 C 73.3 15.1 60.0 12.3 486.7Paul Creek 342-03-007 C 100.0 2.3 166.7 3.9 4326.7NewEcT±, 663-02-002 C 53.3 12.5 400 9.4 426.7111111111111S•treatment plot because the stand will*Ibis stand has two control plots and nonot be thinned.•I 4!	 • M	 - -Species totalIctalInfected	 Mortality•Squaw Valley Flats 848-01-003 T 60.0 5.1 60.0 5.1 1167West Blacktail 833-03-001 T 46.7 10.0 13.3 3.1 427Rear High Bridge 847-02-002 T 20.0 0.7 66.7 2.5 2680Rock Creek 418-04-010 T 40.0 5.4 140.1 18.9 740Verde Face 379-01-034 T 120.1 6.4 160.1 8.5 1880Gilbert Creek 347-06-033 T 46.7 1.5 313.5 9.7 3220Loon Creek 509-04-002 T 53.4 3.8 106.7 7.6 1407Helmer Mtn. 119-03-004 T 46.7 5.8 33.4 4.1 807Five Mile Creek 607-01-061 T 213.4 3.2 380.2 5.7 6720McKillop Road 624-04-005 T 40.0 2.4 100.1 5.9 1700Dead Horse Creek 702-01-003 T 113.4 4.5 180.1 7.2 2513Green Gulch 730-07-001 T 46.7 9.9 33.4 7.1 473Beatrise 831-01-019 T 20.0 5.9 26.7 7.8 340Swiftwater Creek 702-02-006 T 0 0 20.0 6.8 294*Swiftwater Creek 702-02-006 T #2 20.0 3.9 20.0 3.9 513.3Baptiste 446-06-001 T 6.7 1.2 133.4 23.0 580Second Creek 764-01-047 T 20.0 2.8 80.0 11.0 727Paul Creek 342-03-007 T 100.1 1.6 286.8 4.7 6133*This stand has two treatment plots and no control because the stand wasthinned before plots were established.

Establishment report : permanent plots to evaluate the effects of Armillaria root disease in precommercially thinned stands

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Establishment report : permanent plots to evaluate the effects of Armillaria root disease in precommercially thinned stands

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