We present a simple Poisson process model for the growth of Tradescantia fluminensis, an invasive... more We present a simple Poisson process model for the growth of Tradescantia fluminensis, an invasive plant species that inhibits the regeneration of native forest remnants in New Zealand. The model was parameterised with data derived from field experiments in New Zealand and then verified with independent data. The model gave good predictions which showed that its underlying assumptions are sound. However, this simple model had less predictive power for outputs based on variance suggesting that some assumptions were lacking. Therefore, we extended the model to include higher variability between plants thereby improving its predictions. This high variance model suggests that control measures that promote node death at the base of the plant or restrict the main stem growth rate will be more effective than those that reduce the number of branching events. The extended model forms a good basis for assessing the efficacy of various forms of control of this weed, including the recently-relea...
Page 1. Enemy release does not increase performance of Cirsium arvense in New Zealand Michael G. ... more Page 1. Enemy release does not increase performance of Cirsium arvense in New Zealand Michael G. Cripps Grant R. Edwards Graeme W. Bourdôt David J. Saville Hariet L. Hinz Simon V. Fowler Received: 14 May 2009 ...
In New Zealand, research is being performed on the use of the ubiquitous plurivorous ascomycete S... more In New Zealand, research is being performed on the use of the ubiquitous plurivorous ascomycete Sclerotinia sclerotiorum, as a biocontrol agent for Cirsium arvense in pasture. As a consequence of the wide host range of this fungus, the proposed biocontrol may pose a risk to non-target arable plants. Crop disease risk is primarily due to the formation of sclerotia. These
... For the Agribase farm type abbreviations represent beef (BEF), deer (DEE), grazing other peop... more ... For the Agribase farm type abbreviations represent beef (BEF), deer (DEE), grazing other peoples' stock (GRA), not farmedidle (NOF), sheep (SHP), mixed sheep and beef (SNB), and unspecified (UNS) 3716 MS Watt et al. 123 Page 7. for the establishment of future forests. ...
Variation in the width of ‘safety zones’ for sheep and dairy pasture treated with a Sclerotinia s... more Variation in the width of ‘safety zones’ for sheep and dairy pasture treated with a Sclerotinia sclerotiorum (Lib.) de Bary-based mycoherbicide was quantified using 10 years of climate data from each of five regions in New Zealand. Acceptable and risk-averse zones were defined as the maximum distances in any direction from a treated pasture where ‘added:natural’ ratios of air-borne S.
Recent research in Europe has suggested that stem mining insects may be important for vectoring t... more Recent research in Europe has suggested that stem mining insects may be important for vectoring the pathogen Puccinia punctiformis, and largely responsible for its systemic infection in the weed, Cirsium arvense. However, here we present comparative survey data showing that ...
Factors promoting pathogenicity of Fusarium tumidum on gorse (Ulex europaeus) were determined to ... more Factors promoting pathogenicity of Fusarium tumidum on gorse (Ulex europaeus) were determined to develop a novel strategy for delivering this potential mycoherbicide using insects as vectors of inoculum. Fusarium tumidum sprayed as a suspension of 1×10 conidia mL on at least 50% of a gorse plant reduced shoot dry weight by 45% (P<0.05). A minimum of 910 viable conidia were
Combining specialist herbivory with interspecific plant competition can be an effective means of ... more Combining specialist herbivory with interspecific plant competition can be an effective means of controlling pasture weeds. Cirsium arvense (Canada thistle, Californian thistle, creeping thistle) is one of the worst weeds of pastoral production systems in New Zealand (NZ). The oligophagous leaf-feeding beetle, Cassida rubiginosa, was recently released in NZ for control of C. arvense. To assess the impact of this biocontrol agent we conducted an outdoor potted-plant experiment with low and high densities of Cassida larvae combined with different levels of interspecific competition from typical NZ pasture species. Secondly, we carried out a field-release experiment to quantify the impact of high densities of Cassida under more natural conditions. Interspecific competition reduced all measured plant parameters of C. arvense except mean shoot height and base diameter. Herbivory by Cassida only reduced root biomass, and showed a weak additive response when combined with competition. All other measured parameters of C. arvense showed a substitutive response, with competition being the only factor having a significant impact on the weed. There were no significant synergistic interactions with competition and herbivory on C. arvense. Interestingly, the number of root buds per plant was significantly greater in the presence of herbivory by Cassida, suggesting that C. arvense may compensate for defoliation. Similar to the potted-plant experiment, Cassida had no significant effect on shoot growth and development in the field-release experiment. The results of this study indicate that competition from typical NZ pasture species is a more important factor than herbivory by Cassida, and unless Cassida reaches outbreak densities, it will likely have an insignificant impact on this weed.
Page 1. ORIGINAL PAPER Influence of insects and fungal pathogens on individual and population par... more Page 1. ORIGINAL PAPER Influence of insects and fungal pathogens on individual and population parameters of Cirsium arvense in its native and introduced ranges Michael G. Cripps Graeme W. Bourdôt David J. Saville Hariet L. Hinz Simon V. Fowler Grant R. Edwards ...
We present a simple Poisson process model for the growth of Tradescantia fluminensis, an invasive... more We present a simple Poisson process model for the growth of Tradescantia fluminensis, an invasive plant species that inhibits the regeneration of native forest remnants in New Zealand. The model was parameterised with data derived from field experiments in New Zealand and then verified with independent data. The model gave good predictions which showed that its underlying assumptions are sound. However, this simple model had less predictive power for outputs based on variance suggesting that some assumptions were lacking. Therefore, we extended the model to include higher variability between plants thereby improving its predictions. This high variance model suggests that control measures that promote node death at the base of the plant or restrict the main stem growth rate will be more effective than those that reduce the number of branching events. The extended model forms a good basis for assessing the efficacy of various forms of control of this weed, including the recently-relea...
Page 1. Enemy release does not increase performance of Cirsium arvense in New Zealand Michael G. ... more Page 1. Enemy release does not increase performance of Cirsium arvense in New Zealand Michael G. Cripps Grant R. Edwards Graeme W. Bourdôt David J. Saville Hariet L. Hinz Simon V. Fowler Received: 14 May 2009 ...
In New Zealand, research is being performed on the use of the ubiquitous plurivorous ascomycete S... more In New Zealand, research is being performed on the use of the ubiquitous plurivorous ascomycete Sclerotinia sclerotiorum, as a biocontrol agent for Cirsium arvense in pasture. As a consequence of the wide host range of this fungus, the proposed biocontrol may pose a risk to non-target arable plants. Crop disease risk is primarily due to the formation of sclerotia. These
... For the Agribase farm type abbreviations represent beef (BEF), deer (DEE), grazing other peop... more ... For the Agribase farm type abbreviations represent beef (BEF), deer (DEE), grazing other peoples' stock (GRA), not farmedidle (NOF), sheep (SHP), mixed sheep and beef (SNB), and unspecified (UNS) 3716 MS Watt et al. 123 Page 7. for the establishment of future forests. ...
Variation in the width of ‘safety zones’ for sheep and dairy pasture treated with a Sclerotinia s... more Variation in the width of ‘safety zones’ for sheep and dairy pasture treated with a Sclerotinia sclerotiorum (Lib.) de Bary-based mycoherbicide was quantified using 10 years of climate data from each of five regions in New Zealand. Acceptable and risk-averse zones were defined as the maximum distances in any direction from a treated pasture where ‘added:natural’ ratios of air-borne S.
Recent research in Europe has suggested that stem mining insects may be important for vectoring t... more Recent research in Europe has suggested that stem mining insects may be important for vectoring the pathogen Puccinia punctiformis, and largely responsible for its systemic infection in the weed, Cirsium arvense. However, here we present comparative survey data showing that ...
Factors promoting pathogenicity of Fusarium tumidum on gorse (Ulex europaeus) were determined to ... more Factors promoting pathogenicity of Fusarium tumidum on gorse (Ulex europaeus) were determined to develop a novel strategy for delivering this potential mycoherbicide using insects as vectors of inoculum. Fusarium tumidum sprayed as a suspension of 1×10 conidia mL on at least 50% of a gorse plant reduced shoot dry weight by 45% (P<0.05). A minimum of 910 viable conidia were
Combining specialist herbivory with interspecific plant competition can be an effective means of ... more Combining specialist herbivory with interspecific plant competition can be an effective means of controlling pasture weeds. Cirsium arvense (Canada thistle, Californian thistle, creeping thistle) is one of the worst weeds of pastoral production systems in New Zealand (NZ). The oligophagous leaf-feeding beetle, Cassida rubiginosa, was recently released in NZ for control of C. arvense. To assess the impact of this biocontrol agent we conducted an outdoor potted-plant experiment with low and high densities of Cassida larvae combined with different levels of interspecific competition from typical NZ pasture species. Secondly, we carried out a field-release experiment to quantify the impact of high densities of Cassida under more natural conditions. Interspecific competition reduced all measured plant parameters of C. arvense except mean shoot height and base diameter. Herbivory by Cassida only reduced root biomass, and showed a weak additive response when combined with competition. All other measured parameters of C. arvense showed a substitutive response, with competition being the only factor having a significant impact on the weed. There were no significant synergistic interactions with competition and herbivory on C. arvense. Interestingly, the number of root buds per plant was significantly greater in the presence of herbivory by Cassida, suggesting that C. arvense may compensate for defoliation. Similar to the potted-plant experiment, Cassida had no significant effect on shoot growth and development in the field-release experiment. The results of this study indicate that competition from typical NZ pasture species is a more important factor than herbivory by Cassida, and unless Cassida reaches outbreak densities, it will likely have an insignificant impact on this weed.
Page 1. ORIGINAL PAPER Influence of insects and fungal pathogens on individual and population par... more Page 1. ORIGINAL PAPER Influence of insects and fungal pathogens on individual and population parameters of Cirsium arvense in its native and introduced ranges Michael G. Cripps Graeme W. Bourdôt David J. Saville Hariet L. Hinz Simon V. Fowler Grant R. Edwards ...
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