Test précoce pour l'évaluation de la sensibilité de peupliers hybrides au chancre septorien

Septoria musiva, a fungal pathogen that causes cankers and leaf spots, is found in hybrid poplar plantations (Populus spp.) in southern Québec. A high incidence of severe cankers is observed on susceptible poplars. To accelerate the evaluation for resistance to Septoria canker, sprouts were inoculated with S. musiva twice in the nursery. From the 725 clones tested, 100 showed a low degree of susceptibility. Among these, 45 belong to the Ageiros section, 13 to the Tacamahaca section and 42 are hybrids between the two sections. The four isolates used in this test demonstrate variations in aggressiveness. Key words: Septoria musiva, Septoria canker, screening for resistance, hybrid poplars.

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Biological Control of Septoria Leaf Spot Disease of Hybrid Poplar in the Field

Plant Disease ◽

10.1094/pdis.2003.87.7.809 ◽

2003 ◽

Vol 87 (7) ◽

pp. 809-813 ◽

Cited By ~ 17

Author(s):

Laszlo Gyenis ◽

Neil A. Anderson ◽

Michael E. Ostry

Keyword(s):

Biological Control ◽

Leaf Spot ◽

Field Experiments ◽

Hybrid Poplar ◽

Leaf Spot Disease ◽

Leaf Disease ◽

Hybrid Poplars ◽

Septoria Musiva ◽

Triton X ◽

Septoria Leaf Spot

Biological control of Septoria leaf spot of hybrid poplars was investigated using disease-suppressive Streptomyces strains. Field experiments were conducted in 1998 and 1999 on potted trees placed in a hybrid poplar plantation near Rosemount, MN, and on field-planted trees in 1998 at St. Paul. At both locations, one resistant and three susceptible hybrid poplar clones were sprayed with Streptomyces spore suspensions and exposed to natural field inoculum of Septoria musiva. In the 1998 potted-tree experiment, strains GS-93-3, 93, and Mycostop in Tergitol or Triton X-100 solutions applied every 7 days significantly reduced leaf disease by 29 to 83% compared with the controls. In the 1999 potted-tree experiment, Streptomyces strain mixtures in Tergitol solution applied every 5 days significantly reduced leaf disease by 50 to 87% compared with the controls. In the 1998 plantation experiment, strains GS-93-3, 93, or Mycostop in Tergitol solution applied weekly, bi-monthly, or monthly significantly reduced leaf disease in all treatments by 64 to 78% compared with the controls.

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Isolation and characterization of Bacillus velezensis EB14, an endophytic bacterial strain antagonistic to poplar stem canker pathogen Sphaerulina musiva and its interactions with the endophytic fungal microbiome in poplars.

PhytoFrontiers™ ◽

10.1094/phytofr-10-20-0023-r ◽

2021 ◽

Author(s):

Sachin Naik ◽

Sylvester Palys ◽

Marcos Di Falco ◽

Adrian Tsang ◽

Pierre Périnet ◽

...

Keyword(s):

Bacterial Strain ◽

Boreal Forests ◽

Pathogenic Fungus ◽

Hybrid Poplar ◽

Stem Canker ◽

Bacillus Velezensis ◽

Hybrid Poplars ◽

Leaf Spots ◽

Isolation And Characterization ◽

Poplar Trees

Species of the genus Populus commonly known as poplars are one of the most widely used groups of forest trees in North America and Europe, and play a significant ecological role as a pioneer species in boreal forests, and as a dominant species in the riparian forests that serve as wildlife habitats and watersheds. Natural and artificial hybrids of poplars are being extensively used in commercial plantations. However, many hybrid poplar trees are susceptible to Sphaerulina musiva, the pathogenic fungus that causes leaf spots and stem cankers and limits the utility of hybrid poplars as a plantation trees. We isolated an endophytic bacterial strain Bacillus velezensis EB14 from a Populus hybrid which showed a strong antifungal activity against S. musiva. Through mass spectrometric analyses of co-cultured B. velezensis EB14 and S. musiva, we identified five cyclic lipopeptides produced by B. velezensis EB14 – Iturin A1, Iturin A2, Iturin A9, Subtulene A and Fengycin. In addition, B. velezensis EB14 produced four major unidentified compounds in co-cultivation with S. musiva. The cyclopeptide production by B. velezensis EB14 was more pronounced (20-1000 fold) in the co-cultured plates due to elicitation by S. musiva. We also discovered that the native endophytic B. velezensis EB14 strain exhibited different levels of interactions against the endophytic fungal microbiomes of Populus sp. Overall, our results indicate B. velezensis EB14 strain as a promising biocontrol agent that could be used against stem canker and leaf spot diseases caused by S. musiva in Poplar plantations.

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Clone by isolate interaction in the hybrid poplar – Septoria musiva pathosystem

Canadian Journal of Forest Research ◽

10.1139/x08-042 ◽

2008 ◽

Vol 38 (7) ◽

pp. 1888-1896 ◽

Cited By ~ 9

Author(s):

Jared M. LeBoldus ◽

Peter V. Blenis ◽

Barb R. Thomas

Keyword(s):

Native Species ◽

Populus Deltoides ◽

Hybrid Poplar ◽

Interaction Effects ◽

Resistance Screening ◽

Preliminary Screening ◽

Screening Programs ◽

Hybrid Poplars ◽

Septoria Musiva ◽

Explained Variation

Fourteen clones of hybrid poplar were inoculated with 19 isolates of Septoria musiva Peck under greenhouse conditions to determine the magnitude of the clone, isolate, and clone × isolate interaction effects. Septoria musiva isolates were collected from five geographic areas, two symptoms (canker and leaf spot), and two host types (native species and hybrid poplar). The hybrid poplar clones were classified by parent type ( Populus deltoides Bartr. ex Marsh., Populus laurifolia Lebed. × Populus nigra L., and P. deltoides × (P. laurifolia × P. nigra)). There were no significant differences among geographic areas (p = 0.443), symptoms (p = 0.842), or hosts (p = 0.304) of origin for the 19 isolates nor significant differences among the three parent types (p = 0.089). Clone, isolate, and clone × isolate interaction effects were all significant, accounting for 65%, 15%, and 18%, respectively, of the explained variation. These results indicate that clones rather than parent types should be the focus of resistance screening programs and that the pathosystem should be stable given the relatively small clone × isolate interaction. These results also indicate that a single isolate should be sufficient for preliminary screening of disease resistance in hybrid poplars.

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First Report of Shining Willow as a Host Plant for Septoria musiva

Plant Disease ◽

10.1094/pdis.2004.88.7.770b ◽

2004 ◽

Vol 88 (7) ◽

pp. 770-770 ◽

Cited By ~ 6

Author(s):

N. Feau ◽

L. Bernier

Keyword(s):

Leaf Spot ◽

Hybrid Poplar ◽

Internal Transcribed Spacers ◽

Morphological Description ◽

Water Control ◽

First Report ◽

Leaf Spots ◽

Poplar Clone ◽

Septoria Musiva ◽

Leaf Disks

During the summer of 2001, leaf spots resembling those caused by Septoria musiva Peck. were observed on shining willow (Salix lucida Mühl. subsp. lucida) at Leclerville, Québec, Canada (46°34′19″N,71°59′35″W). Affected leaves had brown, necrotic leaf spots (>5mm in diameter) surrounded by a darker brown halo. Conidia were cylindrical, straight to curved with 1 to 4 septa, 28 to 54 × 3.5 to 4 μm, and were produced in pycnidia located on the abaxial surface in the center of the leaf spots. The causal agent of this disease was successfully isolated by germinating the conidia on corn meal agar that was supplemented with streptomycin (50mg/ml) and chloramphenicol (300mg/ml) and followed with the transfer of the germinated conidia to potato dextrose agar. Leaf symptoms and morphology matched those of S. musiva, the cause of leaf spot and stem canker of hybrid poplars in North America (2,4). The internal transcribed spacers and the 5.8S portion of the rDNA were amplified using PCR with the ITS1 (5′-TCC GTA GGT GAA CCT GCG G-3′) and ITS2 (5′-GCT GCG TTC TTC ATC GAT GC-3′) primer pair on total genomic DNA extracted from a pure culture of the pathogen. The rDNA sequence obtained (GenBank Accession No. AY555277) had 100% identity at 506 base positions with the ITS1, 5.8S, and ITS2 of three S. musiva isolates from Québec and one from Wisconsin (GenBank Accession Nos. AY549464 to AY549467). To test for pathogenicity, excised leaf disks from plants propagated by softwood cuttings of the source plant and from one hybrid poplar clone (Populus maximowiczii × P. xjackii) were inoculated with 3 μl of a suspension of ground mycelium or sterile water (control). Disks were placed in a 24-well tissue culture plate with 1 ml of distilled water per well and incubated in a growth room maintained at 22°C with a 16-h photoperiod. After 1 month, symptoms were similar to those previously observed. Isolates collected from shining willow or hybrid poplar were able to induce S. musiva leaf spot symptoms on leaf disks excised from shining willow or the hybrid poplar clone. From symptomatic leaf disks, S. musiva was consistently reisolated. To our knowledge, this is the first report of S. musiva on a member of the genus Salix. S. didyma, S. salicicola, and S. salicina have been reported from leaves of species of Salix (1,3). Only a vague morphological description of S. didyma was found (3). Moreover, conidia of S. salicicola (20 to 50 × 2.5 to 3.5 μm) and S. salicina (40 to 60 μm long, unspecified width) overlap dimensions of S. musiva conidia (1). There is a need to reexamine the relationships between these species of Septoria. Evidently, the complete host range of S. musiva is not yet known. References: (1) L. Lanier et al. Mycologie et Pathologie Forestières. Masson. Paris, 1978. (2) M. E. Ostry. Eur. J. For. Pathol. 17:158, 1987. (3) P. A. Saccardo. Sylloge fungurum omnium hucusque cognitorum. Patavii: Sumptibus Auctoris, 1882. (4) L. J. Spielman et al. Plant Dis. 70:968, 1986.

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Some characteristics of soil respiration in hybrid poplar plantations in northern Alberta

Canadian Journal of Soil Science ◽

10.4141/s05-083 ◽

2006 ◽

Vol 86 (Special Issue) ◽

pp. 257-268 ◽

Cited By ~ 23

Author(s):

D. D. Saurette ◽

S. X. Chang ◽

B. R. Thomas

Keyword(s):

Soil Respiration ◽

Hybrid Poplar ◽

Diurnal Fluctuation ◽

Simulated Rainfall ◽

Control Field ◽

Organic C ◽

Hybrid Poplars ◽

Poplar Plantations ◽

The Impact ◽

Northern Alberta

Fast-growing hybrid poplars are being planted in the Canadian prairies to meet the increasing demand for fibre and environmental services of trees and forests; however, the impact of hybrid poplars on C dynamics and storage on previously farmed land is largely unknown for the boreal region. We measured soil CO2 efflux along a chronosequence (3-, 9-, and 11-yr-old stands) of hybrid poplar (Populus deltoides × Populus × petrowskyana var. Walker) plantations and a control agricultural field from June to August 2004. Measurements were made between 0800 and 1800 with a portable Li-Cor 6400-09 system and were based on 4–5 min averaging. We also measured the response to simulated rainfall and the diurnal fluctuation of soil CO2 efflux. Soil CO2 efflux ranged from 1.30 µmol CO2 m-2 s-1 in the 3-yr old plantation to 5.41 µmol CO2 m-2 s-1 in the agricultural control field, or from 0.17 ìmol CO2 m-2 s-1 kg-1 C (based on soil organic C content to a 0.4 m depth) in the 3-yr-old plantation to 1.09 µmol CO2 m-2 s-1 kg-1 C in the 11-yr-old plantation. Simulated rainfall applied in the 3-yr-old plantation and a newly planted site resulted in an immediate pulse of CO2 efflux, 2.90 and 2.54 µmol CO2 m-2 s-1, respectively, followed by an efflux rate sustained slightly above pre-irrigation levels. No secondary pulse of soil respiration was observed in the 2-h period following water application. Diurnal variation of soil respiration was found to be small between 0600 and 1900 in the agricultural control field, with values that varied from 2.66 to 3.17 µmol CO2 m-2 s-1. Continued monitoring of soil respiration and other C cycling processes in the chronosequence will improve our understanding of the potential for C sequestration in hybrid poplar plantations in northern Alberta. Key words: Carbon sequestration, greenhouse gas emissions, biomass, boreal forest, land-use change, hybrid poplar

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Hybrid poplar yields in Québec: Implications for a sustainable forest zoning management system

The Forestry Chronicle ◽

10.5558/tfc2012-075 ◽

2012 ◽

Vol 88 (04) ◽

pp. 391-407 ◽

Cited By ~ 9

Author(s):

Julien Fortier ◽

Benoit Truax ◽

Daniel Gagnon ◽

France Lambert

Keyword(s):

Management System ◽

Forest Cover ◽

Hybrid Poplar ◽

Forest Conversion ◽

P Availability ◽

Yield Data ◽

Soil P ◽

Hybrid Poplars ◽

Forest Sites ◽

Poplar Plantations

In the province of Québec, approximately 12 000 ha of fast-growing poplar plantations are managed by industrials, while small private landowners have planted only 1000 ha. Most of these poplar plantations are established on clearcut forest sites (approx. 11 000 ha). What are the yields of these hybrid poplar plantations? In this article, available yield data are presented and discussed in the context of a sustainable forest zoning management system. In southern Québec, three factors are highly correlated to yield for clones of various parentages: NO3supply rate in riparian soils, elevation (or climate) and soil P availability in abandoned farmland soils. Many Québec forest sites, particularly in the boreal shield ecozone, have acidic soils and harsh climate, with low mineralization rates. They generally cannot fulfill the very high nutrient requirements of hybrid poplars. Within a forest zoning management system, hybrid poplar plantations and agroforestry should be located in priority in southern Québec landscapes, with low remaining natural forest cover, and where intensive agriculture is the dominant land-use. This strategy will increase biodiversity and the provision of ecosystem services. Elsewhere, intensive trembling aspen regeneration silviculture could be a sustainable alternative to forest conversion into hybrid poplar plantations.

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The Histology of Hybrid Poplar Clones Inoculated with Septoria musiva

Plant Disease ◽

10.1094/pdis-91-12-1524 ◽

2007 ◽

Vol 91 (12) ◽

pp. 1524-1530 ◽

Cited By ~ 10

Author(s):

Jerry E. Weiland ◽

Glen R. Stanosz

Keyword(s):

Hybrid Poplar ◽

Host Responses ◽

Fungal Colonization ◽

Wound Surface ◽

Hybrid Poplars ◽

Poplar Clones ◽

Agar Plug ◽

Septoria Musiva ◽

Tissue Responses ◽

Stem Cankers

Septoria musiva causes stem cankers that severely limit production of susceptible hybrid poplars in eastern North America. A field experiment was conducted with resistant clone DN34 and susceptible clone NC11505 in order to (i) identify tissues colonized by the pathogen, (ii) describe tissue responses to S. musiva, and (iii) determine whether tissue responses to S. musiva differed between hybrid poplar clones. Branches of each clone were inoculated by removing the fourth or fifth fully expanded leaf and placing an agar plug colonized by an aggressive isolate of S. musiva over the wound. Seven weeks after inoculation, branches were harvested and prepared for histology. Data from nonwounded control, wounded control, and wounded and inoculated stems were collected and analyzed for effects of clone and treatment. In general, fungal colonization was more extensive in NC11505 and exophylactic and necrophylactic periderms (NPs) of clone DN34 were significantly thicker than those of NC11505, regardless of treatment. The number of NPs produced and the distance from the epidermis to the outermost layer of phellem were significantly affected by the pathogen. Inoculated stems of clone DN34 developed a single NP that formed closer to the wound surface than in wounded controls. In contrast, inoculated stems of NC11505 developed successive NPs and the first NP formed further from the wound surface than in wounded controls. These two host responses to inoculation, as well as measures of exophylactic and necrophylactic periderm thickness, may be useful as markers for the selection of poplar resistant to damage by S. musiva.

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