The weed suppressive ability of selected Australian grain crops; case studies from the Riverina region in New South Wales (original) (raw)
Related papers
2019
Herbicide resistance in both grasses and broadleaf weeds is on the rise across Australia, with an increasing number of cropping weeds experiencing resistance to multiple herbicides. One contributing factor to this issue is the adoption of conservation agriculture (CA). CA is a system of residue management that avoids the use of cultivation for the establishment of annual broadacre crops. Another contributing factor is poor management of herbicide mode of action strategies in broadacre farming. One key tool for integrated weed management (IWM) strategies is the use of competitive grain crop cultivars and postharvest crop residues, which can effectively suppress, or delay weed seedling emergence and provide an initial advantage for the crop in terms of early weed suppression. The ability of various dual-purpose grazing or non-grazing grain crops and their residues to suppress weeds until subsequent planting the following year was compared in two successive field experiments in the Riv...
We evaluated ten grain crops and their residues for their ability to suppress both winter and summer annual weeds in the mixed cropping region of southern Australia due to their competitive abilities and the presence of residues remaining until the subsequent cropping season. Research was conducted in Wagga Wagga NSW, in 2012 and 2013 using replicated RCB designs. Trends in weed suppression among years were similar. Weed pressures and yields were moderate in 2012-13 and lower in 2013-2014, due to rainfall received. Yields averaged 2.3-4 tons ha −1 for all crops in both seasons. Winter weeds were well suppressed in crop in 2013 but annual ryegrass (Lolium rigidum Gaud.) was less well suppressed in 2012. Annual weeds established following harvest and included witchgrass (Panicum capillare L.) and fleabane (Conyza spp.). Witchgrass was most suppressed in grazing wheat and canola stubbles, followed by hybrid canola stubbles in both years. Grazing canola residues suppressed nearly all witchgrass and most fleabane growth for up to 4 months following harvest. Soil analyses for weed suppressive allelochemicals potentially produced by canola residues were performed.
2018
In 2014–2016, replicated field trials were performed to evaluate mechanisms of weed suppression in Australian canola genotypes in moderate to low rainfall zones at Wagga Wagga (572 mm) and Condobolin (449 mm) NSW, respectively. In 2015–2016, a split plot design with and without trifluralin as the main plot and cultivar as the sub plot was employed for trials; in this experiment 8 cultivars including hybrid and open-pollinated cultivars were assessed. At each site, crop and weed growth were monitored at various phenological stages including early season, vegetative, grain-filling, harvest and post-harvest. Certain cultivars exhibiting early vigour and also the ability to intercept light due to leaf canopy structure were associated with increased suppression of in-crop weed growth in canola trials; in addition, improved post-harvest weed suppression was associated with the presence of remaining crop residues after harvest. Cultivars GT-50, Hyola 600RR and Hyola 50 were Field evaluatio...
Crop & Pasture Science, 2022
The introduction of harvest weed seed control (HWSC) techniques and associated machinery has enabled the routine use of an alternative weed control technology at a novel weed control timing in global grain cropping fields. Driven by the significant threat of widespread populations of annual ryegrass (Lolium rigidum) with multiple-herbicide resistance, in the 1990s Australian growers and researchers developed techniques to target, at grain harvest, the seed production of annual ryegrass and other important weed species. The HWSC approach to weed management is now routinely used by a majority of Australian grain producers as an integral component of effective weed control programs. Here we detail the development and introduction of current HWSC systems and describe their efficacy in Australian grain production systems. The use of HWSC has likely contributed to lower annual ryegrass population densities and thus mitigated the impacts of herbicide resistance as well as slowing further evolution of resistance. In addition, low weed densities enable the introduction of site-specific weed control technologies and the opportunity to target specific in-crop weeds with non-selective alternative weed control techniques. With an awareness of the evolutionary potential of weed species to adapt to all forms of weed control, there is an understanding that HWSC treatments need to be judiciously used in grain cropping systems to ensure their ongoing efficacy. The successful use of Australian developed HWSC systems has attracted global interest and there is now a considerable international research effort aimed at introducing this alternative weed control approach and timing into the world's major cropping systems.
Archives of Agronomy and Soil Science, 2019
Weeds are a major constraint to canola (Brassica napus L.) production, reducing grain yield and quality. The repeated use of pre-and post-emergent herbicides to control several grasses and broadleaf weeds has escalated the problem of herbicide resistance in weeds. The development of herbicide-tolerant canola cultivars has increased the flexibility of weed management but has also increased the risks of outcrossing with wild relatives and weed shifts to resistance. Herbicideresistant weed species, and the related biological repercussions, pose a major threat to sustainable weed management. These developing risks have led researchers to examine integrated weed management (IWM) techniques for sustainable weed control. Weed control strategies using non-A c c e p t e d M a n u s c r i p t chemical tactics have valid roles for managing weeds. However, in broad-acre commercial fields, the effectiveness of several non-chemical selections are less proven than commercial chemical herbicides. Canola competition and allelopathy for weed suppression are potential components for integrated weed management in canola. This review examines current chemical and nonchemical options available for developing IWM strategies for profitable canola production, as well as future research directions.
Research priorities for weed suppression by crops in Australia
2018
Crop competition is an important tactic for suppressing weed growth and maintaining crop yield, especially with the increasing levels of herbicide resistance in Australia. In 2015, a team of weed scientists from the western, southern and northern grain production regions conducted a comprehensive review of research on crop competition in Australia, funded by the Grains Research and Development Corporation (GRDC). The aim of the study was to enable a 20% increase in grower adoption of this tactic for weed suppression by 2020. The project team: identified priority weed species; conducted a meta-analysis of pooled data to identify common trends; conducted a knowledge gap analysis based on the literature review and the meta-analysis; defined an approach for improved future crop competition experimentation; and identified and provided recommendations for future Research, Development and Extension (RD&E). An updated assessment of priority and key weed species was provided. The need for mo...
2019
It is estimated that in the United States, agronomic weeds are responsible for about 50% of crop yield loss, costing nearly $27 billion each year. As interest in cover crops across the Midwest increases, so does the need to understand when to terminate cover crops for maximum weed control while still maintaining crop yield. Field experiments were conducted in 2017 and 2018 in Indiana to evaluate the effect of cover crop termination timings on weed control, and corn and soybean yield. Cereal rye (<i>Secale cereale </i>L.) and canola (<i>Brassica napus </i>L.) were subjected to early- or late- termination utilizing glyphosate-, saflufenacil- or glufosinate-based burndown herbicide programs. In corn, cereal rye and canola reduced early season weed biomass by 58 to 67% compared to fallow (no cover crop) plots. Cereal rye and canola reduced horseweed (<i>Erigeron canadensis </i>L.) and giant ragweed (<i>Ambrosia trifida </i>L.) emergence by...
Euphytica, 2008
Cereal cultivars conferring a high degree of crop competitive ability, especially against aggressive weeds, are highly beneficial in organic farming as well as other farming systems that aim to limit the use of herbicides. In this study, thirteen winter wheat cultivars, plus one spring wheat and one winter oat were assessed for their competitive ability at key growth stages, across three seasons. The natural population of weed species was allowed develop without agronomic intervention. Weed suppression ability for each cultivar (S var ) was calculated as the difference between weed growth in plots for each cultivar and the maximal weed growth (W max ) from adjacent uncropped areas. The sensitivity of S var in response to changes in weed growth (S var W ) was derived from the linear regression coefficient of S var plotted against W max . There was significant variation in S var between cultivars and strong evidence for cultivars to vary in S var W . Amongst groups of cultivars with similar levels of S var some could be defined as being of higher or lower sensitivity to changes in weed growth. Some cultivars also had relatively good S var at high levels of weed growth. The use of both weed suppression ability and sensitivity across different levels of weed growth or weed populations has considerable potential for selecting new cultivars suitable for organic agriculture. Ideally new cultivars will be selected on the basis of high S var and/or low S var W . This analysis provides the means to measure sensitivity of cultivar performance across a range of favourable and unfavourable conditions.
Advances in Weed Management for Organic Cereal Production in Southeast Australia
2000
Organic cereal production in southeast Australia is challenging for producers due to a range of influences such as weeds and low soil available phosphorus. Two experiments were conducted on a certified organic property at Berrigan NSW during 2001-2003 to investigate 'within crop' weed management and forage crop management for weed control. Sowing later using a short season wheat cultivar did