Summary. Spraytopping, the application of a low rate of non-selective herbicide (usually glyphosate or paraquat) to annual grass seed heads in the spring or early summer for seed set control is widely practised throughout Australia. While grasses are the targets of the spray treatment, annual pasture legumes may also be damaged by spraytopping, particularly if the legumes are flowering at the time of application. The effect of applying glyphosate (90, 112 or 162 g a.i./ha), paraquat (100 g a.i./ha) and glyphosate plus MCPA (90 + 150 g a.i./ha) to subterranean clover (Trifolium subterraneum L. cv. Dalkeith) and annual medic (Medicago polymorpha L. cvv. Serena, Santiago and Circle Valley) pastures at various times during flowering was investigated during the spring of 1993 and 1994. Experiments were located at Tincurrin and Tenindewa, Western Australia. Subterranean clover seed yield was most affected by applications of glyphosate (90 and 162 g a.i./ha) and glyphosate plus MCPA (90 + 150 g a.i./ha) during early–mid flowering. Seed yield was reduced by as much as 88% following application of glyphosate plus MCPA when 20% of the subterranean clover plants were flowering. Treatment with paraquat (100 g a.i./ha) during mid–late flowering reduced seed yield of subterranean clover by 25–50% in experiment 1 only. Medic seed yield was reduced up to 90% depending on cultivar when glyphosate (112 g a.i./ha) was applied during early–mid flowering. In addition to seed yield, the level of hard seed was assessed. Treatment of subterranean clover during early–mid flowering with glyphosate (90 and 162 g a.i./ha) significantly reduced the quantity of hard seed produced. Thirty–forty percent of subterranean clover seed was germinable soon after seed set, compared with 7–17% germinable for the seed from untreated plants. Treatment with glyphosate (112 g a.i./ha) reduced the proportion of hard seed in the medics when applied during mid flowering. Treatment with paraquat had little effect on the proportion of hard seed formed. This work demonstrates that using a spraytopping technique for control of seed set in annual grasses may dramatically reduce seed yield in pasture legumes. Spraytopping can further reduce the ability of legumes to persist in cropping rotations by reducing the amount of hard seed formed. Implications for practical farming systems are outlined.
The ability of 2,2-dichloropropionic acid (2,2-DPA) to control annual grasses was examined in a 4-year-old medic (Medicago polymorpha var. brevispina cv. Circle Valley) pasture. Six rates of 2,2-DPA with and without spray adjuvants (1% spray oil + 0.25% wetting agent) were used: 0.37, 0.56, 0.74, 1.11, 1.48, 2.22 kg a.i./ha. The pasture was sprayed in July at the 4-true-leaf stage of the medic, after identifying and counting grasses and medics. Plants were counted again after spraying and grass seed heads were counted in spring. At the end of the season, medic seed yields were obtained. Nine annual pasture legumes were later evaluated for their tolerance to 2.22 kg 2,2-DPA/ha at 3 growth stages [post plant, pre-emergence (PPPE); 3-5-true-leaf stage; flowering] under weed-free conditions. A rate of 1.11 kg 2,2-DPAJha was found to reduce barley grass density by 85%. Efficacy was improved, however, with higher rates and/or the addition of spray adjuvants. Because of low silvergrass (Vulpia spp.) and ryegrass (Lolium rigidurn) plant numbers, it was not possible to assess whether 2,2-DPA controlled these species effectively. There was no effect of herbicide on medic seed yields, seed weight, seed number per pod, or seed germination. Medic seed yields were well correlated with plant density of medic but not with herbicide rates. There was a wide variation in biomass production of the 9 pasture legumes in the evaluation of tolerance, when assessed by visual rating and seed yield, with significant biomass and yield reductions at all timings of application of 2,2-DPA. Subterranean clover (Trifoliurn subterraneum L.) was the most severely affected. Generally, medic species tolerated 2,2-DPA well. Serena was the most susceptible medic cultivar at any treatment time, with seed yield reductions at the first 2 times of application. The results suggest that 2,2-DPA could be used safely on annual medics for the control of barley grass, and possibly other annual grasses.
Background Understanding how and why de-implementation of low-value practices is sustained remains unclear. The Paediatric Research in Emergency Departments International CollaboraTive (PREDICT) Bronchiolitis Knowledge Translation (KT) Study was a cluster randomised controlled trial conducted in 26 Australian and New Zealand hospitals (May-November 2017). Results showed targeted, theory-informed interventions (clinical leads, stakeholder meetings, train-the-trainer workshop, targeted educational package, audit/feedback) were effective at reducing use of five low-value practices for bronchiolitis (salbutamol, glucocorticoids, antibiotics, adrenaline and chest x-ray) by 14.1% in acute care settings. The primary aim of this study is to determine the sustainability (continued receipt of benefits) of these outcomes at intervention hospitals two-years after the removal of study supports. Secondary aims are to determine sustainability at one-year after removal of study support at intervention hospitals; improvements one-and-two years at control hospitals; and explore factors that influence sustainability at intervention hospitals and contribute to improvements at control hospitals. Methods A mixed-methods study design. The quantitative component is a retrospective medical record audit of bronchiolitis management within 24 hours of emergency department (ED) presentations at 26 Australian (n = 20) and New Zealand (n = 6) hospitals, which participated in the PREDICT Bronchiolitis KT Study. Data for a total of 1800 infants from intervention and control sites (up to 150 per site) will be collected to determine if improvements (i.e., no use of all five low-value practices) were sustained two- years (2019) post-trial (primary outcome; composite score); and a further 1800 infants from intervention and control sites will be collected to determine sustained improvements one- year (2018) post-trial (secondary outcome). An a priori definition of sustainability will be used. The qualitative component will consist of semi-structured interviews with three to five key emergency department and paediatric inpatient medical and nursing staff per site (total n = 78-130). Factors that may have contributed to sustaining outcomes and/or interventions will be explored and mapped to an established sustainability framework. Discussion This study will improve our understanding of the sustainability of evidence-based bronchiolitis management in infants. Results will also advance implementation science research by informing future de-implementation strategies to reduce low-value practices and sustain practice change in paediatric acute care. Trial registration Australian and New Zealand Clinical Trials Registry No: ACTRN12621001287820.
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