Progress 10/01/01 to 09/30/05
Outputs
Cedrus deodara is grown as an ornamental in the Pacific Northwest and southern US. C. deodara occasionally is damaged by dieback of shoot tips, which has been associated with a fungus resembling Sirococcus conigenus. Bleeding cankers observed on 2- to 4-year-old stems of potted nursery stock of C. deodara cv. Karl Fuchs from Clackamas County, OR were dark with indistinct margins, shallow, and up to 30 cm long. Infection apparently originated with twigs that had died. Isolates produced hyaline, fusiform, two-celled conidia typical of S. conigenus. The ISSR-PCR fingerprints of an isolate was consistent with the P group of S. conigenus (mostly from hosts in Picea and Pinus spp.). This isolate was used to inoculate wounded shoots on potted deodar cedars. Sterile agar plugs were applied to wounded control shoots on each tree. After 10 weeks, approx. half of inoculated shoots were blighted and drooped with yellow to brown needles that eventually dropped. The pathogen was
reisolated from all but one symptomatic shoots but not from asymptomatic or control shoots. To our knowledge, this is the first confirmed report of S. conigenus as a pathogen of C. deodara. Variation among isolates of the shoot blight pathogen attributed to S. conigenus, Sirococcus sp., or one of many synonyms was studied. ISSR-PCR fingerprints, nuclear rDNA internal transcribed spacers and 5.8S sequences, and 18S rDNA sequences were analyzed. Culture morphology as well as sizes and shapes of conidia produced on seed cone scales in culture also were compared. Two main groups were distinguished based on genetic markers and cultural characteristics. The P group consists of isolates mostly from pine and spruce from Europe and both eastern and western North America; the T group consists of isolates mostly from hemlock from western North America. Results provide a benchmark for comparison of other isolates of these fungi and indicate the need for additional sampling and comparative
research of these pathogens. Interest in development of multicohort stands of red pine (Pinus resinosa) in the Great Lakes region prompted investigation of potential impact of S. conigenus on understory red pine seedlings. In May 2002 and 2003 healthy, 1-year-old red pine seedlings were planted in the understory of a maturing red pine plantation in northern Wisconsin in an area with a history of this pathogen. Occurrence of shoot blight symptoms was recorded periodically during the summer; seedlings were harvested in fall and examined for signs of pathogens. By fall 2002 and 2003, respectively, shoot blight incidence was 89% and 98% and most seedlings were dying. Pycnidia with conidia of S. conigenus were present on almost all of the symptomatic seedlings. The conifer pathogen Diplodia pinea also was detected, though less frequently. Pycnidia of S. conigenus tended to be found more frequently on symptomatic current year shoots than symptomatic previous year shoots; the opposite was
true for pycnidia of D. pinea. Risk from S. conigenus to understory red pine seedlings should be considered in any plans for development of multicohort red pine stands in areas where the pathogen is present.
Impacts
This new knowledge is expected to be used in development and implementation of biologically rational practices to minimize losses from Sirococcus shoot blight in planted and natural forests.
Publications
- Bronson, J. J. and Stanosz, G. R. 200X. Risk from Sirococcus conigenus to understory red pine seedlings in northern Wisconsin. Forest Pathology (in press)
- Smith, D. R., Bronson, J. J., and Stanosz, G. R. 2003. Host-related variation in the conifer shoot blight pathogen Sirococcus conigenus. Forest Pathology 33:141-156.
- Bronson, J. J., Stanosz, G. R., and Putnam, M. L. 2003. First Report of Sirococcus conigenus on Deodar Cedar in Oregon. Disease Note. Plant Disease 87:1006.
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Progress 01/01/04 to 12/31/04
Outputs
Changes (for aesthetic reasons) in red pine (Pinus resinosa) management practices include creation of irregular, longer edges of harvest sites and leaving residual overstory trees, instead of complete clearcut harvesting before replanting. Also, in a departure from traditional even-aged plantations in which trees of one age are grown, there is increasing interest in development of uneven-aged or multicohort red pine stands, in which trees of several ages would grow together. To confirm the risk of damage from the shoot blight pathogen Sirococcus conigenus (which inhabits crowns of overstory trees) to regeneration in these situations, red pine seedlings were planted in ten 50-seedling plots in the understory of a maturing red pine stand in northcentral Wisconsin in spring 2002 and 2003. Initial seedling establishment and symptom development was recorded during each growing season, and in fall of each year seedlings were harvested to determine the presence of the
pathogen. By fall 2002 and 2003, respectively, mean shoot blight incidence on established seedlings was 89% and 98%. Most of these seedlings were dying or dead and pynidia with conidia of S. conigenus were present on almost all of the seedlings. The shoot blight pathogen Sphaeropsis sapinea also was detected, though much less frequently. These results support previous research and concern about the risk that shoot blight pathogens pose to understory red pine seedlings.
Impacts
This new knowledge is expected to be used in development and implementation of biologically rational practices to minimize losses from Sirococcus shoot blight in planted and natural forests.
Publications
- Bronson, J. J. and Stanosz, G. R. 2004. Risk from Sirococcus conigenus to understory red pine seedlings. Phytopathology 94:S11.
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Progress 01/01/03 to 12/31/03
Outputs
Variation among isolates of the Sirococcus shoot blight pathogen (attributed to Sirococcus conigenus, Sirococcus sp., or one of many synonyms) was studied. Inter-simple-sequence-repeat-anchored polymerase chain reaction fingerprints, nuclear rDNA internal transcribed spacers and 5.8S sequences, and 18S rDNA sequences were analyzed. In addition, culture morphology as well as sizes and shapes of conidia produced on seed cone scales in culture were compared. Two main groups were distinguished based on both genetic markers and cultural characteristics. The P group consists of isolates mostly from pine and spruce from Europe and both eastern and western North America; the T group consists of isolates mostly from hemlock from western North America. Results provide a benchmark for comparison of other isolates of these fungi and indicate the need for additional sampling and comparative research of these pathogens. Cedrus deodara is a highly valued conifer widely grown as an
ornamental in the Pacific Northwest and southern United States. Cedrus deodara in the Pacific Northwest is normally problem-free but occasionally is damaged by dieback of shoot tips, which has been associated with a fungus resembling Sirococcus conigenus. In February 2002, bleeding cankers were observed on 2- to 4-year-old stems of potted nursery stock of C. deodara cv. 'Karl Fuchs' from Clackamas Co., OR. Cankers were dark with indistinct margins, shallow, and up to 30 cm long. Infection appeared to have originated with small twigs that had died. Cultures isolated from discolored bark on streptomycin-amended PDA produced conidiomata with hyaline, fusiform, two-celled conidia typical of S. conigenus. ISSR-PCR fingerprints of an isolate from one of these trees were consistent with the P group of S. conigenus (mostly from hosts in Picea and Pinus). This isolate (02-04, ATCC MYA-2969) was used to inoculate two shoots on each of twelve 3-year-old potted deodar cedars in each of two
trials. Each shoot was wounded by removing a needle, and an agar plug colonized with mycelium was placed over the wound and held in place for 2 weeks with Parafilm. Sterile agar plugs were applied to two wounded control shoots on each tree in each trial. After 10 weeks, 25 out of the 48 inoculated shoots were blighted and drooped, with yellow to brown needles that eventually dropped. The pathogen was reisolated from 24 out of 25 symptomatic shoots but not from asymptomatic or control shoots. To our knowledge, this is the first confirmed report of S. conigenus as a pathogen of C. deodara.
Impacts
This new knowledge is expected to be used in development and implementation of biologically rational practices to minimize losses from Sirococcus shoot blight in planted and natural forests.
Publications
- Smith, D. R., Bronson, J. J., and Stanosz, G. R. 2003. Host-related variation in the conifer shoot blight pathogen Sirococcus conigenus. Forest Pathology 33: 141-156.
- Bronson, J. J., Stanosz, G. R., and Putnam, M. L. 2003. First Report of Sirococcus conigenus on Deodar Cedar in Oregon. Disease Note. Plant Disease 87: 1006.
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Progress 01/01/02 to 12/31/02
Outputs
Variation among isolates of the Sirococcus shoot blight pathogen (attributed to Sirococcus conigenus, Sirococcus sp., or one of many synonyms) was studied. Inter-simple-sequence-repeat-anchored polymerase chain reaction fingerprints, nuclear rDNA internal transcribed spacers and 5.8S sequences, and 18S rDNA sequences were analyzed. In addition, culture morphology as well as sizes and shapes of conidia produced on seed cone scales in culture were compared. Two main groups were distinguished based on both genetic markers and cultural characteristics. The P group consists of isolates mostly from pine and spruce from Europe and both eastern and western North America; the T group consists of isolates mostly from hemlock from western North America. Results provide a benchmark for comparison of other isolates of these fungi and indicate the need for additional sampling and comparative research of these pathogens.
Impacts
Understanding the straing involved inconifer disease may provide management strategies to lower losses.
Publications
- D. R. Smith, J. J. Bronson, and G. R. Stanosz. 2003. Host-related variation among isolates of the Sirococcus shoot blight pathogen from conifers. Forest Pathology (in press).
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Progress 01/01/01 to 12/31/01
Outputs
Initial three months of the project have allowed collection of pathogen isolates and studies on cultural requirements and inoculation procedures to begin.
Impacts
(N/A)
Publications
- No publications reported this period
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