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Graeme W. Bourdôt – One of the best experts on this subject based on the ideXlab platform.

  • Multiple resistance to flumetsulam and MCPA in two clones of Ranunculus Acris
    New Zealand Journal of Agricultural Research, 2020
    Co-Authors: Sarah D. Jackman, Graeme W. Bourdôt, Shona L Lamoureaux, Alasdair Noble, Hossein Ghanizadeh
    Abstract:

    Herbicide dose-responses of seedling progenies of Ranunculus Acris populations varying in herbicide exposure history indicate that this weed has evolved multiple resistance to phenoxycarboxylic aci…

  • Ranunculus Acris control in dairy pasture – a comparison of herbicides, plant growth promoters, a bioherbicide and pregraze mowing
    , 2018
    Co-Authors: Graeme W. Bourdôt, Shona L Lamoureaux, Sarah D. Jackman, Alasdair D. L. Noble, D F Chapman
    Abstract:

    The efficacy of control tactics for Ranunculus Acris was quantified on poorly- and well-drained soils in a factorial experiment conducted over three years in 18 dairy pastures. Soil drainage, gibberellic acid and nitrogenous fertiliser (growth promoters), and a bioherbicide utilising Sclerotinia sclerotiorum had no effect on the cover of R. Acris. The herbicides aminopyralid and aminopyralid+triclopyr, by contrast, gave long-lasting reductions in the cover of the weed and substantial temporary reductions in the clovers. Flumetsulam, thifensulfuron methyl, MCPA, MCPB and MCPB+bentazone were less effective overall. Pregraze mowing reduced R. Acris as the frequency of mowing increased. For all herbicides, there was a 1:1 replacement of R. Acris by grasses and clovers. The efficacy of the treatments varied greatly between pastures, possibly due to genetic differences between the R. Acris populations and their historical exposure to the herbicides.

  • Resistance of Ranunculus Acris to flumetsulam, thifensulfuron-methyl and MCPA in New Zealand dairy pastures
    New Zealand Journal of Agricultural Research, 2015
    Co-Authors: C. S. Lusk, Graeme W. Bourdôt, G. A. Hurrell, Kerry C. Harrington, David J. Saville
    Abstract:

    Research in the 1980s showed that Ranunculus Acris had evolved resistance to the phenoxy herbicides MCPA and MCPB in New Zealand. Since then two ALS-inhibitor herbicides, flumetsulam and thifensulfuron-methyl, have been used but recently flumetsulam has been reported as being less effective. The mortality responses of seedling progeny of 15 R. Acris populations, differing in historical exposure to phenoxy and ALS-inhibitor herbicides, were compared using a log-series of five doses of MCPA, flumetsulam and thifensulfuron-methyl. The resulting mortalities were higher than expected at lower doses, meaning LD50 values were not reliably estimated. In a second experiment, the responses of one population with no previous exposure to herbicides and one population with high exposure to flumetsulam were compared using a wider range of doses of flumetsulam (0.04 to 25 times). The LD50 values differed 5.3-fold between the resistant and susceptible biotypes. In a third experiment, four populations varying in past expo…

David J. Saville – One of the best experts on this subject based on the ideXlab platform.

  • A Petri dish test for detection of flumetsulam and MCPA resistance in giant buttercup (Ranunculus Acris subsp. Acris)
    New Zealand Journal of Agricultural Research, 2019
    Co-Authors: C. S. Lusk, G. A. Hurrell, David J. Saville
    Abstract:

    ABSTRACTA quick test to enable early detection of flumetsulam and MCPA resistance in Ranunculus Acris L. subsp. Acris was developed in a series of Petri dish assays and pot trials. Initial experiments used seeds (Experiment 1) or cotyledonary seedlings (Experiment 2) from two R. Acris populations of known past herbicide exposure, in Petri dishes containing broad ranges of herbicide concentrations. A further seedling assay (Experiment 3) was carried out using refined ranges of herbicide concentrations and four populations of R. Acris of known past herbicide exposure. Percent germination, numbers of new true leaves, root length and green biomass were recorded at intervals after treatment. Results were compared with the LD50 values calculated from dose response pot trials carried out concurrently using the same R. Acris populations and herbicides (Experiment 4), in order to validate the results. Percent green biomass 29 DAT at 5 µM for flumetsulam and 28 DAT at 25–50 µM for MCPA, gave accurate detection of r…

  • Resistance of Ranunculus Acris to flumetsulam, thifensulfuron-methyl and MCPA in New Zealand dairy pastures
    New Zealand Journal of Agricultural Research, 2015
    Co-Authors: C. S. Lusk, Graeme W. Bourdôt, G. A. Hurrell, Kerry C. Harrington, David J. Saville
    Abstract:

    Research in the 1980s showed that Ranunculus Acris had evolved resistance to the phenoxy herbicides MCPA and MCPB in New Zealand. Since then two ALS-inhibitor herbicides, flumetsulam and thifensulfuron-methyl, have been used but recently flumetsulam has been reported as being less effective. The mortality responses of seedling progeny of 15 R. Acris populations, differing in historical exposure to phenoxy and ALS-inhibitor herbicides, were compared using a log-series of five doses of MCPA, flumetsulam and thifensulfuron-methyl. The resulting mortalities were higher than expected at lower doses, meaning LD50 values were not reliably estimated. In a second experiment, the responses of one population with no previous exposure to herbicides and one population with high exposure to flumetsulam were compared using a wider range of doses of flumetsulam (0.04 to 25 times). The LD50 values differed 5.3-fold between the resistant and susceptible biotypes. In a third experiment, four populations varying in past expo…

  • Pathogenicity of Sclerotinia sclerotiorum on Ranunculus Acris in Dairy Pasture
    Biocontrol Science and Technology, 1999
    Co-Authors: L. J. Cornwallis, A. Stewart, Graeme W. Bourdôt, R. E. Gaunt, I. C. Harvey, David J. Saville
    Abstract:

    Fifty-four isolates of Sclerotinia sclerotiorum from Ranunculus Acris and other natural hosts were applied as mycelial infested kibbled wheat onto 6 month-old R. Acris plants in two glasshouse screening experiments. Most isolates (90%) did not differ in their pathogenicity towards R. Acris. One isolate, S. sclerotiorum G45, was selected based on its ability to cause severe disease and suppress regeneration of R. Acris. A field experiment was conducted to determine the efficacy of S. sclerotiorum (G45) against R. Acris in infested dairy pastures in the Takaka Valley, Golden Bay, New Zealand. Isolate G45 was formulated as a wettable powder and was applied as a slurry at 20 and 40 ml/plant in December 1995. After 10 weeks, regeneration from the crown of treated plants was apparent and a second application of S. sclerotiorum was made in February 1996. Best control of R. Acris was obtained when the plants were inoculated in full flower in December. At the first time of treatment, the 40 ml application of S. sc…

G. A. Hurrell – One of the best experts on this subject based on the ideXlab platform.

  • A Petri dish test for detection of flumetsulam and MCPA resistance in giant buttercup (Ranunculus Acris subsp. Acris)
    New Zealand Journal of Agricultural Research, 2019
    Co-Authors: C. S. Lusk, G. A. Hurrell, David J. Saville
    Abstract:

    ABSTRACTA quick test to enable early detection of flumetsulam and MCPA resistance in Ranunculus Acris L. subsp. Acris was developed in a series of Petri dish assays and pot trials. Initial experiments used seeds (Experiment 1) or cotyledonary seedlings (Experiment 2) from two R. Acris populations of known past herbicide exposure, in Petri dishes containing broad ranges of herbicide concentrations. A further seedling assay (Experiment 3) was carried out using refined ranges of herbicide concentrations and four populations of R. Acris of known past herbicide exposure. Percent germination, numbers of new true leaves, root length and green biomass were recorded at intervals after treatment. Results were compared with the LD50 values calculated from dose response pot trials carried out concurrently using the same R. Acris populations and herbicides (Experiment 4), in order to validate the results. Percent green biomass 29 DAT at 5 µM for flumetsulam and 28 DAT at 25–50 µM for MCPA, gave accurate detection of r…

  • Resistance of Ranunculus Acris to flumetsulam, thifensulfuron-methyl and MCPA in New Zealand dairy pastures
    New Zealand Journal of Agricultural Research, 2015
    Co-Authors: C. S. Lusk, Graeme W. Bourdôt, G. A. Hurrell, Kerry C. Harrington, David J. Saville
    Abstract:

    Research in the 1980s showed that Ranunculus Acris had evolved resistance to the phenoxy herbicides MCPA and MCPB in New Zealand. Since then two ALS-inhibitor herbicides, flumetsulam and thifensulfuron-methyl, have been used but recently flumetsulam has been reported as being less effective. The mortality responses of seedling progeny of 15 R. Acris populations, differing in historical exposure to phenoxy and ALS-inhibitor herbicides, were compared using a log-series of five doses of MCPA, flumetsulam and thifensulfuron-methyl. The resulting mortalities were higher than expected at lower doses, meaning LD50 values were not reliably estimated. In a second experiment, the responses of one population with no previous exposure to herbicides and one population with high exposure to flumetsulam were compared using a wider range of doses of flumetsulam (0.04 to 25 times). The LD50 values differed 5.3-fold between the resistant and susceptible biotypes. In a third experiment, four populations varying in past expo…

  • Pasture tolerance and efficacy of three herbicides used against giant buttercup (Ranunculus Acris subsp. Acris L.)
    New Zealand Plant Protection, 2011
    Co-Authors: C. S. Lusk, Graeme W. Bourdôt, Kerry C. Harrington, G. A. Hurrell
    Abstract:

    The herbicides flumetsulam, thifensulfuron-methyl and MCPA were compared for their efficacy against giant buttercup (Ranunculus Acris subsp. Acris L.) and their damage to perennial ryegrass (Lolium perenne) and white clover (Trifolium repens). The tolerance of perennial ryegrass and white clover to five rates of each herbicide was measured using swards either sown in pots or transplanted from the field. The total clover yield harvested over 5 months from newly-sown pasture was 80, 59 and 4% of the untreated control for flumetsulam, thifensulfuron-methyl and MCPA applied at label rates and 95, 40 and 30% for transplanted swards respectively. The biomass yield of giant buttercup 3 months after treatment was 1, 22 and 2% of the untreated control for flumetsulam, thifensulfuron-methyl and MCPA applied at the label rate. Together these experiments suggest that flumetsulam is the most effective and least pasture-damaging of these three herbicides.

Artur Pliszko – One of the best experts on this subject based on the ideXlab platform.

  • Comparative analysis of phenolic compounds in four taxa of Erigeron Acris s. l. (Asteraceae)
    Biologia, 2019
    Co-Authors: Edyta Nalewajko-sieliwoniuk, Artur Pliszko, Jolanta Nazaruk, Eliza Barszczewska, Weronika Pukszta
    Abstract:

    The aim of the present work was to investigate and compare the content of phenolic compounds in four taxa of Erigeron Acris L. s. l.: E. Acris (EAA), E. Acris subsp. droebachiensis (O.F. Müll.) Arcang. (EAD), E. Acris subsp. serotinus (Weihe) Greuter (EAS) and E . × huelsenii Vatke (EH), a hybrid between E. Acris and E. canadensis L. The total flavonoid content was determined by Christ-Müller method and the total phenolic acid content was determined by the method utilizing Arnov’s reagent. The method using ultra high performance liquid chrochromatography with photodiode array detection (UHPLC-PDA) was applied for the separation, identification and quantification of nine phenolic compounds (protocatechuic acid, chlorogenic acid, caffeic acid, 6′- O -caffeoylerigeroside, scutellarein-7- O -β-D-glucuronide, quercetin 3- O –glucoside, 4,5-dicaffeoylquinic acid, quercetin and luteolin) in the aerial parts of E. Acris s. l. The chromatographic separation was carried out using a BEH C_18 column packed with 1.7-μm particles and gradient elutelution with a mobile phase of water and methanol, both containing 0.02% ( v /v) trifluoroacetic acid. The four investigated taxa of E. Acris s. l. differed in the composition and the content of phenolic compounds. The main substances determined in the methanolic herbal extracts were: scutellarein-7- O -β-D-glucuronide (EAA, EAS, EAD and EH), 6′- O- caffeoylerigeroside (EAA, EAD and EH) and chlorogenic acid (EAS and EH). Moreover, the results indicated that five of the nine tested compounds were found in all investigated extracts from herbs of E. Acris s. l. Two of them (6′- O -caffeoylerigeroside and scutellarein-7- O -β-D-glucuronide) could be selected as potential chemotaxonomic markers of the genus Erigeron L.

  • Erigeron Acris L. subsp. angulosus (Gaudin) Vacc. (Asteraceae), a new taxon in the flora of Poland
    Acta Botanica Croatica, 2018
    Co-Authors: Artur Pliszko
    Abstract:

    The paper reports for the first time the occurrence of Erigeron Acris subsp. angulosus in Poland. This rare European temperate plant was found in August 2014 in a former sand and gravel quarry, close to the Sobolewo reservoir in the town of Suwalki, north-eastern Poland. Species composition of the habitat is characterized by a phytosociological releve based on the Braun-Blanquet method, diagnostic characters in comparison to the morphologically similar E. Acris subsp. droebachiensis are presented using scanning electron microscopy imaging, and an identification key for E. Acris s. l. in Poland is given.

  • Erigeron Acris subsp. baicalensis (Asteraceae), a new combination in Asian Erigeron
    Acta Musei Silesiae Scientiae Naturales, 2016
    Co-Authors: Artur Pliszko
    Abstract:

    Erigeron Acris subsp. baicalensis (Botsch.) A. Pliszko is proposed as a new combination for Asian E. baicalensis Botsch.

Ørjan Totland – One of the best experts on this subject based on the ideXlab platform.

  • Limitations on reproduction in alpine Ranunculus Acris
    Canadian Journal of Botany, 1997
    Co-Authors: Ørjan Totland
    Abstract:

    This study examines experimentally the influence of limiting factors on seed to ovule ratio and seed weight in three alpine populations of the perennial herb Ranunculus Acris L. at Finse, southwest Norway. To test for pollen and resource limitation, seed production of supplementally pollinated or completely defoliated plants was compared to that of untreated plants. In one population the experiment was repeated twice during the season. In mid-season, supplemental hand-pollination had no significant effect on seed to ovule ratio, but significantly increased the seed weight, whereas complete defoliation resulted in a significant decrease in seed to ovule ratio and a marginally significant decrease in seed weight. These results indicate that pollen limitation occurred on seed weight and resource limitation mainly on seed to ovule ratio. Seed production in late-flowering control and defoliated plants in one population was nearly completely absent, whereas supplemental pollination increased seed production sub…

  • Intraseasonal variation in pollination intensity and seed set in an alpine population of Ranunculus Acris in southwestern Norway
    Ecography, 1994
    Co-Authors: Ørjan Totland
    Abstract:

    I studied aspects of the pollination and reproduction ecology of an alpine population of the circurnpolar Ranunculus Acris (Ranunculaceae) at Hardangervidda, southwest Norway Dipteran families, mainly Muscidae and Anthomyudae, were the most frequent flower visitors and pollinators A single visit by these insects resulted in a seed set of c 18% of the total potential Visitation rates were highest early m the flowering season The longevity of individual flowers of early flowering plants was c 3 d shorter than that of mid-season flowering individuals Insect pollinators moved short distances between flowers and they mostly visited near neighbour plants Expenments showed that Ranunculus Acris was self-incompatible and thus dependent on insect visitation for seed production Early flowering individuals had a very high seed set relative to individuals flowering in mid- and late season, suggesting a strong selection pressure for early flowering in the population Seed production in this Ranunculus Acris population seems to be limited by severe climatic conditions and a low pollination intensity