, Volume 143, Issue 3, pp 449–457 | Cite as

Competition, facilitation, and niche differentiation in two foliar pathogens

  • F. A. Al-Naimi
  • K. A. GarrettEmail author
  • W. W. Bockus
Community Ecology


We studied competition between the obligate biotroph Puccinia triticina (designated here as Puccinia) and the facultative saprophyte Pyrenophora tritici-repentis (designated here as Pyrenophora) in older and younger leaves in a set of three host genotypes selected to be resistant to Puccinia only, Pyrenophora only, or neither. Age-related resistance is important for both of these pathogens. The facultative saprophyte Pyrenophora was generally a stronger competitor than the biotrophic Puccinia, even experiencing facilitation from the presence of Puccinia when Pyrenophora had the advantage of earlier inoculation. Both pathogen species produced the most spores when they were introduced before the competing species and more spores when introduced simultaneously compared to after the competitor. The pre-interactive niche of Puccinia was larger than the post-interactive niche and sporulation by Puccinia was substantially reduced in environments in which Pyrenophora had high sporulation rates. The pre-interactive niche of Pyrenophora was similar to the post-interactive niche and Pyrenophora had proportionally lower reductions in sporulation due to interspecific competition in the pre-interactive niche.


Facultative saprophytes Impact niche Obligate parasites Requirement niche Rust fungi 



We thank S. P. Dendy for assistance with the experiments and R. L. Bowden, A. Jumpponen, and Oecologia reviewers for comments that improved this work. This work was supported in part by NSF grant DEB-0130692, NSF grant EPS-0236913 with matching funds from the Kansas Technology Enterprise Corporation, NSF grant EPS-9874732 with matching support from the State of Kansas, the NSF Long-Term Ecological Research Program at Konza Prairie, and USDA grant 2002-34103-11746. This is Kansas State Experiment Station Contribution No. 05-29-J. The experiments reported here were performed in the U.S.A. and comply with the current laws of the U.S.A.


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Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • F. A. Al-Naimi
    • 1
    • 2
  • K. A. Garrett
    • 1
    Email author
  • W. W. Bockus
    • 1
  1. 1.Department of Plant Pathology, 4024 Throckmorton Plant Sciences CenterKansas State UniversityManhattanUSA
  2. 2.Biology DepartmentUniversity of QatarDohaQatar

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