Pathogenicity Tests of Gremmeniella Abietina Var. Balsamea Isolated from Balsam Fir in Canada Tests Du Pouvoir Pathogène De Gremmeniella Abietina Var

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Phytoprotection

Pathogenicity tests of Gremmeniella abietina var. balsamea isolated from balsam fir in Canada Tests du pouvoir pathogène de Gremmeniella abietina var. balsamea isolé du sapin baumier au Canada Edgar Smerlis † et Gaston Laflamme

Volume 91, 2010–2011 Résumé de l'article Gremmeniella abietina var. balsamea isolé du sapin baumier (Abies balsamea) a URI : https://id.erudit.org/iderudit/1008542ar été soumis à une épreuve de pouvoir pathogène chez différentes espèces de DOI : https://doi.org/10.7202/1008542ar conifères, y compris A. balsamea. Le pouvoir pathogène de ce champignon était positif seulement sur le sapin baumier. Ce champignon pathogène n’a pu Aller au sommaire du numéro infecter d’autres conifères, pas même les épinettes qui sont pourtant des hôtes reconnus du taxon G. abietina var. balsamea. De plus, les isolats provenant des épinettes et des pins étaient pathogènes seulement sur leurs hôtes respectifs. Éditeur(s) Ces résultats soulèvent des questions quant au statut taxonomique des deux champignons pathogènes classés comme G. abietina var. balsamea. Société de protection des plantes du Québec (SPPQ)

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Citer cet article Smerlis †, E. & Laflamme, G. (2010). Pathogenicity tests of Gremmeniella abietina var. balsamea isolated from balsam fir in Canada. Phytoprotection, 91, 19–21. https://doi.org/10.7202/1008542ar

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Edgar Smerlis† and Gaston Laflamme1

Received 2011-04-30; accepted 2011-09-29

PHYTOPROTECTION 91 : 19-21

The pathogenicity of Gremmeniella abietina var. balsamea isolated from balsam fir (Abies balsamea) was tested on different conifer hosts, including A. balsamea. Pathogenicity of the fungus was positive on balsam fir only. This pathogen could not infect other conifers, not even spruce species which are reported as hosts for the taxon G. abietina var. balsamea. Also, isolates from spruces and pines were pathogenic only on their respective hosts. These results raise questions on the taxonomic status of the two pathogens classified as G. abietina var. balsamea. Keywords: Scleroderris canker, Picea mariana, Pinus banksiana.

[Tests du pouvoir pathogène de Gremmeniella abietina var. balsamea isolé du sapin baumier au Canada] Gremmeniella abietina var. balsamea isolé du sapin baumier (Abies balsamea) a été soumis à une épreuve de pouvoir pathogène chez différentes espèces de conifères, y compris A. balsamea. Le pouvoir pathogène de ce champignon était positif seulement sur le sapin baumier. Ce champignon pathogène n’a pu infecter d’autres conifères, pas même les épinettes qui sont pourtant des hôtes reconnus du taxon G. abietina var. balsamea. De plus, les isolats provenant des épinettes et des pins étaient pathogènes seulement sur leurs hôtes respectifs. Ces résultats soulèvent des questions quant au statut taxonomique des deux champignons pathogènes classés comme G. abietina var. balsamea. Mots clés : Chancre scléroderrien, Picea mariana, Pinus banksiana.

Gremmeniella abietina (Lagerb.) Morelet is frequent- In this note, we present results on fungal isolation ly found on Pinus spp. (Morelet 1969), and it also from diseased balsam fir leaders as well as the results occurs on balsam fir (Abies balsamea (L.) Mill.) in the of pathogenicity tests conducted using isolates from boreal forest of North America. On balsam fir, this naturally occurring cankers caused by G. abietina var. fungus was recognized as the taxon Gremmeniella balsamea on balsam fir and black spruce and by abietina (Lagerb.) Morelet var. balsamea Petrini, G. abietina var. abietina on jack pine and red pine Petrini, Laflamme & Ouellette (Petrini et al. 1989). This (North American race). Cross inoculations were per- variety also comprises Gremmeniella entities occur- formed in 1983 on several conifer hosts to prove ring on spruces, namely white spruce (Picea glauca through Koch’s postulate the pathogenicity of these (Moench) Voss) and black spruce (P. mariana (Mill.) Gremmeniella isolates. B.S.P.). Smerlis (1967) tested the pathogenicity of dif- Isolations from diseased balsam fir stem leaders ferent isolates of Gremmeniella on several native were made in 1983 from samples collected in the conifer species in Quebec. The results from his trial Réserve faunique des Laurentides (47°35’N; 71°13’W), show that the isolates from black spruce caused Quebec, Canada. Three small pieces of necrotic bark symptoms on Picea spp., but not on A. balsamea, were cut with a sterile scalpel, surface sterilized for Larix spp., or Pinus spp. (Smerlis 1967). Another 5 s in 1% HgC1 solution, washed in sterile distilled pathogenicity test conducted by Smerlis (1968) gave 2 water and placed in tubes containing 3% malt agar. erratic results and the author suggested that the use The cultures were incubated at 15°C. A total of 100 of recently transplanted or suppressed trees may leaders were sampled. have caused such results. Later, and under field con- ditions using well-established trees, Laflamme et al. Twenty-one different fungi were isolated from the (1996) tested the host preference of six isolates, two naturally infected balsam fir leaders. Gremmeniella per host, from naturally regenerated black spruce, abietina var. balsamea was obtained from 89% of the balsam fir and jack pine (Pinus banksiana Lamb.). Our samples. Sydowia polyspora (Brev. & v. Tav.) E. Müll. results clearly showed that each isolate thrives on the ranked second with a frequency of 31%. Lophium host from which it was isolated. mytilinum (Pers. ex Fr.) Fr. and Epicoccum purpurascens

1. Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, Québec, Québec, Canada G1V 4C7; corresponding author e-mail: [email protected] †. This experiment was conducted by the first author before he retired from the Canadian Forest Service in 1987. This information was brought to the attention of the second author after Smerlis’s death in 2003.

19 PHYTOPROTECTION 91 (2010-2011) isolates of 67°07’W) intheMataneregion.Two monoconidial region, andinSaint-Jean-de-Cherbourg(48°51’N; at LacAlbanel(50°54’N;73°18’W)intheJamesBay the twootherswerepreparedfromsamplescollected nated fromtheRéservefauniquedesLaurentidesand asinocula;fourculturesorigi- balsam firwereused hemlock ( (47°41’N;69°44’W),andthoseoneastern Kamouraska ascospore isolatesof previously describedbySmerlis(1969).Sixmono- cutting atongue-likesectioninthebark,method removing needlesfromthebaseofshootsand of 1983oncurrent-yearstemorbranchleadersby conidia isolates,iii)ascospores,andiv)conidia. monoascospore isolates,ii)myceliumfrommono- inoculations werecarriedoutwithi)myceliumfrom of theCanadianForestService,nearQuebecCity. The ed attheValcartier ForestStation(46°54’N;71°29’W) 72°00’W). Theothertreespecies(Table 1)weretreat- Saint-Louis-de-Blandford, Arthabasca(46°15’N; abietina depressa Moench) andgroundjuniper( des Laurentides.Inoculationswith were used;theyoriginatedfromtheRéservefaunique tified fungirangedinfrequenciesfrom1to6%. of theleaders,respectively. Theothermostlyuniden- Ehrenb. exSchlecht.wereisolatedfrom21and16% lected inSaint-Urbain(47°33’N;70°32’W)the North Americanstrainpreparedfromspecimenscol- monoascospore andonemonoconidialisolateofthe Tsuga canadensis Tsuga occidentalis Thuja canadensis Taxus sylvestris P. strobus P. resinosa P. contorta P. banksiana Pinus rubens P. mariana P. glauca P. abies Picea laricina Larix horizontalis J. communis Juniperus balsamea Abies suspensions; +=symptoms;-nosymptoms monoascospore isolates,2=myceliumfrommonoconidial3ascosporesdischargedapothecia,and4conidial from jackpineandred(NorthAmericanrace)onseveralconiferspecieswithfourtypesofinoculum:1=mycelium from Resultsofinoculationwith Table 1. talis All inoculationswithmyceliumweredoneinthefall Inoculations oneasternwhitecedar( L.), creepingjuniper( from jackpinewerecarriedoutwithone Pursh) weredonein1983Saint-André-de- Tsuga canadensis Tsuga G. abietina G. Tree species var. .abietina G. var. depressa balsamea (L.) Carr.) weredonein Juniperus horizontalis Juniperus Gremmeniella abietina Gremmeniella J. communis J. var. G. abietina G. from balsamfir balsamea Thuja occiden- Thuja L. var. ++++ 2413 1234 1234 1234 - + + ------+ ------balsamea from var. G . var. a . var. 20 ( balsamea Abies Distilled waterwasappliedonthecontrolplots. anymore. ber ofconidiapermLisnotavailable suspension withahand-operatedsprayer. Thenum- Each treatedplotwassprayedwith25mLofspore tree speciesatthepreviouslymentionedlocalities. from fructificationsofsamplescollectedonthethree pycnidia per100mLofdistilledwater, weremade Laurentides. seedlings. Branchesofredpine( mature apotheciawereattachedtoawireoverthe described (Smerlis1976).Inshort,branchesbearing discharged fromapotheciahasalreadybeen Table 1.Themethodofinoculationwithascospores been planted.Thetreespeciestreatedarelistedin on 50cmxplotswhichnineseedlingshad ried outinValcartier inmid-Julyof1983duplicate tained at15°C. were madeon3%maltagarandthetubesmain- able anymore.Isolationsfrompositiveinoculations lum from5to23,buttheoriginaldataarenotavail- ranged innumberpertreespeciesorsourceofinocu- grown on3%maltagarat15°C.Theinoculations Réserve fauniquedesLaurentides.Allcultureswere dial isolatepreparedfromspecimenscollectedinthe in 1983withonemonoascosporeandmonoconi- those ofblackspruceandbalsamfir( (48°35’N; 72°21’W)intheLac-Saint-Jeanregion,and American strain)werecollectedinSainte-Hedwidge balsamea Charlevoix region.Finally, inoculationswith bearing apotheciaof na ) Conidial suspensions,preparedattherateoffour Inoculations withascosporesandconidiawerecar- var. from balsamfirandspruce balsamea ++++ ++++ ------balsamea ) werecollectedintheRéservefauniquedes G . a . var. from blacksprucewerecarriedout ( Picea G. abietina G. ) .abietina G. ++++ ++++ var. abietina P. resinosa P. G abietina G. abietina G. . a . var. ( Pinus var. .abieti- G. abietina (North ) Ait.) var. SMERLIS AND LAFLAMME: PATHOGENICITY OF GREMMENIELLA ABIETINA VAR. BALSAMEA

Inoculations with pure cultures of G. abietina var. differentiation in G. abietina var. balsamea is support- balsamea from balsam fir on that host resulted in ed by sequences of the ITS region. symptoms ranging in frequencies from 67 to 100%. In view of the host specificity of Gremmeniella Cankers up to 8 cm long, generally causing mortality found on spruces and balsam fir in eastern Canada, of the inoculated leaders, were formed. The fungus as well as the differences shown by phylogenic stud- was reisolated from all sets of inoculations, although ies, we strongly suggest reviewing the taxonomic sta- not from all individual infections tested. Pycnidia of tus of the two fungal pathogens causing diseases on G. abietina var. balsamea with conidia developed dur- spruce and balsam fir, which are currently included in ing the first summer following the inoculations on the taxon G. abietina var. balsamea. some of the leaders treated with cultures of either form of the spores. Apothecia were observed on dead leaders the second summer after the inoculations. ACKNOWLEDGEMENTS Treatments with ascospores or conidial suspensions of G. abietina var. balsamea from balsam fir similarly The assistance provided by the late Marcel Saint- resulted in symptoms only on balsam fir (Table 1). All Laurent, technician at the Laurentian Forestry Centre, inoculated balsam fir seedlings were infected. is acknowledged. We thank Pierre DesRochers and Applications of conidial suspensions caused symp- Danny Rioux for their critical reading of the manu- toms manifested by defoliation of most or all branch script, and Louis Parrot, former professor at leaders and also of the stem terminal. The defoliation Université Laval, for his assistance with the search of was generally associated with subsequent mortality Smerlis’s documents. of the seedlings. The inoculations with mycelium of G. abietina var. balsamea from balsam fir on the other tree species REFERENCES were all negative (Table 1). Controls where distilled Hamelin, R.C., and J. Rail. 1997. Phylogeny of Gremmeniella water was applied, likewise, showed no signs or spp. based on sequences of the 5.8S rDNA and internal symptoms. transcribed spacer region. Can. J. Bot. 75 : 693-698. Inoculations with G. abietina var. abietina (North Laflamme, G., A. Ylimartimo, and R. Blais. 1996. Host preference of two Gremmeniella abietina varieties on balsam American strain) and G. abietina var. balsamea from fir, jack pine and black spruce in eastern Canada. Can. J. spruce by any of the three methods caused symp- Plant Pathol. 18 : 330-334. toms on pines and spruces, respectively, and they Morelet, M. 1969. Un discomycète inoperculé nouveau. Bull. were not pathogenic on balsam fir (Table 1). Controls Soc. Sci. Nat. Archéol. 183 : 9. showed no signs or symptoms. Petrini, O., L.E. Petrini, G. Laflamme, and G.B. Ouellette. 1989. Taxonomic position of Gremmeniella abietina and These pathogenicity tests show that G. abietina var. related species: a reappraisal. Can. J. Bot. 67 : 2805-2814. balsamea from balsam fir is pathogenic only on bal- Smerlis, E. 1967. Occurrence and pathogenicity of sam fir. It also shows that G. abietina var. balsamea Scleroderris lagerbergii in Quebec. Plant Dis. Rep. 51 : from spruce is pathogenic only on spruce as was 584-585. demonstrated previously on four spruce species: P. Smerlis, E. 1968. Additional information on the pathogenici- glauca, P. mariana, P. rubens Sarg., and P. abies (L.) ty of Scleroderris lagerbergii. Plant Dis. Rep. 52 : 738-739. Karst. (Smerlis 1967). Finally, G. abietina var. abietina Smerlis, E. 1969. Synonymy and pathogenicity of Dermea piceina. Can. J. Bot. 47 : 213-214. caused diseases only on pine species. Smerlis, E. 1976. Evaluation of fungicides for control of In the reappraisal of the genus Gremmeniella, Gremmeniella abietina. I. Laboratory and preliminary Petrini et al. (1989) decided not to create new species field assays. Can. For. Serv., Laurentian For. Res. Cent., of Gremmeniella found on spruce and balsam fir in Info. Rep. LAU-X-23. eastern Canada because of the lack of well-defined morphological differences between specimens from pines, spruces and balsam fir. Dimensions of asci, ascospores and conidia showed overlaps from specimens collected on these tree species. However, elec- trophoresis showed four different patterns among the reference cultures, two on pines (North American race and European race), one on Larix spp., and the other one represented by isolates from spruces and balsam fir in eastern Canada. On that basis, Petrini et al. (1989) created two varieties inside the type species, the variety abietina, mainly found on pines, and the variety balsamea, affecting spruce and balsam fir in the province of Quebec (Canada). Also, a phylogeny study of Gremmeniella spp. based on sequences of the 5.8S rDNA and internal transcribed spacer (ITS) region shows a level of divergence of ITS between the two varieties abietina and balsamea as large as the level of divergence between the species G. laricina and G. abietina var. abietina or between G. laricina and G. abietina var. balsamea (Hamelin and Rail 1997). In the same study, the host-related genetic