02398nas a2200241   4500008004100000245010400041210006900145300001500214490000700229520165400236653003801890653001801928653001701946653001301963653002401976653001602000100001402016700001702030700001502047700001302062700001802075856006302093       2013                        eng d00aSpatial connectedness of plant species: potential links for apparent competition via plant diseases0 aSpatial connectedness of plant species potential links for appar  a1195 -14280 v623 a<p>This study evaluated the reactions of seven common C4 grasses of the tallgrass prairie of the USA Great Plains to the economically important wheat pathogens Pyrenophora tritici-repentis and Gaeumannomyces graminis var. tritici (Ggt) isolated from wheat. The P. tritici-repentis isolates (race 1) were pathogenic on all grasses tested, but symptom severity was markedly low. Three of the grass species inoculated with Ggt were highly susceptible, while four species exhibited no symptoms. Because measures of connectedness can provide a proxy for population processes, connectedness was evaluated within and among the seven grass species in representative tallgrass prairie environments for all potential pathogen-sharing patterns. Andropogon gerardii was ubiquitous, so all plant species were well connected to it. Andropogon scoparius (= Schizachyrium scoparium), Sorghastrum nutans and Panicum virgatum were fairly common but specialized to particular environments. Bouteloua curtipendula was uncommon but occurred in all environments, while Buchloë dactyloides and Bouteloua gracilis were uncommon and only occurred in upland sites. Co-occurrence of plant species was generally not reciprocal in that, for many species pairs, species A rarely occurred without potential exposure to inoculum from species B, while species B commonly occurred without species A. The three grass species susceptible to Ggt may act as sources of inoculum for each other within tallgrass prairie, with the potential to influence fitness, and tallgrass prairie and commercial wheat ecosystems in the Great Plains also have the potential to share both pathogens.</p>10aagriculture–wildlands interface10abiofuel crops10agraph theory10anetworks10apathogen spill-over10aswitchgrass1 aCox, C.M.1 aBockus, W.W.1 aHolt, R.D.1 aFang, L.1 aGarrett, K.A.  uhttps://onlinelibrary.wiley.com/doi/full/10.1111/ppa.1204501901nas a2200205   4500008004100000245008100041210006900122300001300191490000800204520121900212653002801431653001701459653002301476653002201499653001501521100001701536700001801553700001701571856010701588       2005                        eng d00aCompetition, facilitation, and niche differentiation in two foliar pathogens0 aCompetition facilitation and niche differentiation in two foliar  a449 -4570 v1433 aWe 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.10aFacultative saprophytes10aImpact niche10aObligate parasites10aRequirement niche10aRust fungi1 aAl-Naimi, F.1 aGarrett, K.A.1 aBockus, W.W.  uhttp://knz.lternet.edu/content/competition-facilitation-and-niche-differentiation-two-foliar-pathogens