Connolly, John

Lüscher, Andreas

Suter, Matthias

English

University of Kentucky

University of Kentucky UKnowledge International Grassland Congress Proceedings XXI International Grassland Congress / VIII International Rangeland Congress Effect of Grassland Management on the Occurrence of the Poisonous Species Senecio jacobaea Matthias Suter Swiss Grassland Society, Switzerland John Connolly University College Dublin, Ireland Andreas Lüscher Agroscope Reckenholz-Tänikon Research Station, Switzerland Follow this and additional works at: https://uknowledge.uky.edu/igc  Part of the Plant Sciences Commons, and the Soil Science Commons This document is available at https://uknowledge.uky.edu/igc/21/16-1/28 The XXI International Grassland Congress / VIII International Rangeland Congress took place in Hohhot, China from June 29 through July 5, 2008. Proceedings edited by Organizing Committee of 2008 IGC/IRC Conference Published by Guangdong People's Publishing House This Event is brought to you for free and open access by the Plant and Soil Sciences at UKnowledge. It has been accepted for inclusion in International Grassland Congress Proceedings by an authorized administrator of UKnowledge. For more information, please contact UKnowledge@lsv.uky.edu. 瞯 ]826　 瞯 　 Multifunctional Grasslands in a Changing World 　 Volume Ⅱ 　Grasslands/Rangelands Production Systems——— Integrated Management of Harmful Organisms of Grasslands/RangelandsEffect of grassland management on the occurrence of the poisonous species Senecio j acobaeaM . Suter 1 ,3 , J . Connolly 2 , A . Lüscher 31 ,3 Sw iss G rassland Society , Reckenholz strasse 191 , 8046 Zürich , Sw itzerland , E‐mail : matthias .suter ＠ art .admin .ch ,2 UCD School o f Mathematical Sciences , University College Dublin , Dublin 4 , I reland , 3 A groscope Reckenholz‐T惫nikonResearch Station A RT , Reckenholz strasse 191 , 8046 Zürich , Sw itzerlandKey words :weed control ,nitrogen applied ,continuous grazing ,openness of sward ,case‐control studyIntroduction Senecio j acobaea L . ( tansy ragwort) is a poisonous weed in grasslands of various continents ( e .g . United States ,Great Britain , Central Europe , New Zealand) . In Central Europe , the species seems to have increased its dispersion in the lastyears . The further spread of the species into farmland must be prevented because S . j acobaea contains pyrrolizidine‐alkaloidsthat are toxic for cattle and other livestock (Duby , １９７５) . We thus conducted a survey in Switzerland to assess the influence ofmanagement practice and site conditions on the occurrence of this species . Our aim was to find a combination of conditionswhere the risk for the occurrence of S . j acobaea was either remarkably high or low . Such data will allow strategies to hinderthe weed摧s dispersion .Materials and methods To reveal links between management practices and the occurrence of S . j acobaea , a case‐control study( Agresti , ２００２) was conducted on agricultural grassland in the northern and central part of Switzerland . Botanical assessmentswere conducted on parcels ( management units) with S . j acobaea occurrence ( cases) and on neighbouring parcels without S .j acobaea ( controls) . For all parcels , we analysed the soil nutrients , texture and pH , and the details of management such asintensity of fertilisation and frequency of defoliation . The influence of the recorded parameters on the occurrence of S . j acobaeawas analysed using multiple logistic regression , the response variable being the presence or absence of S . j acobaea . Therecorded variables were tested with forward selection , and the approximate relative risk , the ratio of the probability of presenceof the weed for two levels of an environmental variable , was calculated following Agresti (２００２ ) .Results All important factors influencing the occurrence of S . j acobaea were related to management ( Table １ ) : Doubling theapplication of nitrogen to １００ kg ha‐１ yr‐１ reduced the risk for S . j acobaea occurrence approximately five‐fold (０ .１９ , Table １) .This means that the species occurred less frequently on intensively fertilised parcels , but had a high risk for occurrence ongrasslands with low nitrogen fertilisation . Swards that had a high percentage of bare soil ( ＞ ２５％ ) had a forty‐fold greater riskfor the occurrence of the species than swards with an bareness of less than ２５％ . Finally , parcels that were under continuous‐extensive grazing ( set stocking ) had an approximately eleven‐fold greater risk for the occurrence of S . j acobaea compared tomown grassland , while rotational grazing did not show significant differences in risks compared to mowing . S . j acobaea wasnot present in intensively managed meadows cut more than twice per year . As an exception , with a high propagule pressurefrom the vicinity , S . j acobaea was also found in intensively grazed pastures and in meadows of moderate management intensity( two cuts) .Conclusions A long‐term control ofS . j acobaea can best be achieved byavoiding sward damage , by replacingcontinuous‐extensive by rotationalgrazing , and by preventing thespecies� seed formation in thepasture and the local vicinity . Wealso conclude that on‐farm surveysconducted as a case‐control study arevery powerful as they provide reliabledata in relatively short time ( Suter etal . , ２００７ ) . Species occurrence canbe linked to the management practiceon farms and a wide range ofenvironmental conditions existingover longer periods .Table 1 V ariables w ith relev ant e f f ects on the occurrence o f S . jacobaea . Estimateso f multip le logistic regression and the calculated relative risk . S igni f icant e f f ectsat P ＜ ０ .０５ are in bold .Variable Regressionestimate Relative risk( compared to the intercept)Intercept报 ‐１ 崓.５０９Nitrogen‐applied ‐０ 崓.０３３ 0  .19 磯磯Openness : High ( ＞ ２５％ ) ３ ~.６９６ 40 N.31Rotational grazing vs mowing ‐０ 崓.０５５ ０ 7.９５Continuous grazing vs mowing ２ ~.４４７ 11 N.56R2 ０ ~.６５８报 The intercept represents grassland that was mown , received available nitrogen of ５０ kg ha‐１ yr‐１ , and had alow openness of sward ( ≤ ２５％ )磯磯 Relative risk for applied nitrogen of １００ kg ha‐１ yr‐１ReferencesAgresti , A . , ２００２ . Categorial data analysis , ２nd edn . New York , US : Wiley .Duby , G .D . , １９７５ . Tansy ragwort : a toxic threat to livestock . Modern Veterinary Practice ５６ , １８５‐１８８ .Suter , M . , Siegrist‐Maag ,S . ,Connolly ,J . ,Lüscher ,A . ,２００７ . Can the occurrence of Senecio jacobaea be influenced bymanagement practice ?Weed Research ４７ , ２６２‐２６９ .

Effect of Grassland Management on the Occurrence of the Poisonous Species \u3ci\u3eSenecio jacobaea\u3c/i\u3e

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Effect of Grassland Management on the Occurrence of the Poisonous Species \u3ci\u3eSenecio jacobaea\u3c/i\u3e

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