Influence of Crop Competition and Harvest Weed Seed Control on Rigid Ryegrass (Lolium rigidum) Seed Retention Height in Wheat Crop Canopies

Weed Science ◽  
2018 ◽  
Vol 66 (5) ◽  
pp. 627-633 ◽  
Author(s):  
Michael J. Walsh ◽  
John C. Broster ◽  
Charlotte Aves ◽  
Stephen B. Powles
Keyword(s):  
Wheat Crop ◽  
Average Height ◽  
Crop Canopy ◽  
Lolium Rigidum ◽  
Weed Seed ◽  
Seed Retention ◽  
Rigid Ryegrass ◽  
Crop Maturity ◽  
Crop Competition

AbstractHarvest weed seed control (HWSC) is an Australian innovation, developed to target high proportions of weed seed retained at crop maturity by many major weed species. There is the potential, however, that a reduction in the average height of retained seed is an adaptation to the long-term use of HWSC practices. With the aim of examining the distribution of rigid ryegrass (Lolium rigidumGaudin) seed through crop canopies, a survey of Australian wheat (Triticum aestivumL.) fields was conducted at crop maturity. Nine sites with medium to long-term HWSC use were specifically included to examine the influence of HWSC use on seed retention height. During the 2013 wheat harvest,L. rigidumand wheat plant samples were collected at five heights downward through the crop canopy (40, 30, 20, 10, and 0 cm above ground level) in 71 wheat fields. Increased crop competition resulted in higher proportions ofL. rigidumseed in the upper crop canopy (>40 cm). The increase in plant height is likely a shade-intolerance response ofL. rigidumplants attempting to capture more light. This plant attribute creates the opportunity to use crop competition to improve HWSC efficacy by increasing the average height of seed retention. Crop competition can, therefore, have a double impact by reducing overallL. rigidumseed production and increasing seed retention height. Examining the distribution of wheat biomass andL. rigidumseed through the crop canopy, we determined that reducing harvest height for HWSC considerably increased the collection ofL. rigidumseed (25%) but to a lesser extent wheat crop biomass (14%). Comparison of + and − HWSC use at nine locations found no evidence of adaptation to this form of weed control following 5 to 10 yr of use. Although the potential for resistance to HWSC remains, these results indicate that this will not readily occur in the field.

Enhanced wheat competition effects on the growth, seed production, and seed retention of major weeds of Australian cropping systems

Weed Science ◽  
2019 ◽  
Vol 67 (6) ◽  
pp. 657-665 ◽  
Author(s):  
Michael J. Walsh
Keyword(s):  
Seed Production ◽  
Wheat Crop ◽  
Crop Canopy ◽  
Raphanus Raphanistrum ◽  
Weed Seed ◽  
Weed Biomass ◽  
Bromus Diandrus ◽  
Seed Retention ◽  
Competition Effects ◽  
Crop Competition

AbstractThe loss of herbicide options due to resistance and lack of new chemistries have delivered the realization that herbicides are a finite resource and weed control alternatives are desperately needed. In Australian conservation cropping, the only available alternatives suited to routine use are the recently introduced harvest weed seed control (HWSC) and the ever-present but undervalued crop competition. Target-neighbor design pot studies examined wheat (Triticum aestivum L.) competition effects on biomass and seed production of rigid ryegrass (Lolium rigidum Gaudin), wild radish (Raphanus raphanistrum L.), ripgut brome (Bromus diandrus Roth), and wild oat (Avena fatua L.). The influence of wheat competition on crop canopy distribution of weed biomass and seed production was also examined. At the current commercially targeted wheat density (120 plants m−2) weed biomass was reduced by 69%, 73%, 72%, and 49% and seed production by 78%, 78%, 77%, and 50% for L. rigidum, R. raphanistrum, B. diandrus, and A. fatua, respectively, when compared with no competition. These results highlighted the importance of uniform wheat crop establishment in minimizing the ongoing impact of weeds. Enhanced what competition (from 120 to 400 plants m−2) resulted in further smaller, but substantial, reductions in biomass (19%, 13%, 20%, and 39%) and seed production (12%, 13%, 17%, and 45%) for L. rigidum, R. raphanistrum, B. diandrus, and A. fatua, respectively. This enhanced competition also increased weed seed retention in the upper crop canopy (>40 cm) by 35% and 31% for L. rigidum and B. diandrus, respectively, but not for A. fatua and R. raphanistrum, for which weed seed retention was already >80% at the wheat density of 120 plants m−2. Enhanced wheat crop competition, then, has the dual effect of restricting the growth and development of L. rigidum, R. raphanistrum, B. diandrus, and A. fatua as well increasing the susceptibility of these weed species to HWSC.

High Seed Retention at Maturity of Annual Weeds Infesting Crop Fields Highlights the Potential for Harvest Weed Seed Control

2014 ◽  
Vol 28 (3) ◽  
pp. 486-493 ◽  
Author(s):  
Michael J. Walsh ◽  
Stephen B. Powles
Keyword(s):  
Seed Production ◽  
Wild Oat ◽  
Annual Ryegrass ◽  
Wild Radish ◽  
Weed Seed ◽  
Seed Retention ◽  
Total Seed ◽  
Annual Weeds ◽  
Brome Grass ◽  
Crop Maturity

Seed production of annual weeds persisting through cropping phases replenishes/establishes viable seed banks from which these weeds will continue to interfere with crop production. Harvest weed seed control (HWSC) systems are now viewed as an effective means of interrupting this process by targeting mature weed seed, preventing seed bank inputs. However, the efficacy of these systems is directly related to the proportion of total seed production that the targeted weed species retains (seed retention) at crop maturity. This study determined the seed retention of the four dominant annual weeds of Australian cropping systems - annual ryegrass, wild radish, brome grass, and wild oat. Beginning at the first opportunity for wheat harvest and on a weekly basis for 28 d afterwards the proportion of total seed production retained above a 15 cm harvest cutting height was determined for these weed species present in wheat crops at nine locations across the Western Australian (WA) wheat-belt. Very high proportions of total seed production were retained at wheat crop maturity for annual ryegrass (85%), wild radish (99%), brome grass (77%), and wild oat (84%). Importantly, seed retention remained high for annual ryegrass and wild radish throughout the 28 d harvest period. At the end of this period, 63 and 79% of total seed production for annual ryegrass and wild radish respectively, was retained above harvest cutting height. However, seed retention for brome grass (41%) and wild oat (39%) was substantially lower after 28 d. High seed retention at crop maturity, as identified here, clearly indicates the potential for HWSC systems to reduce seed bank replenishment and diminish subsequent crop interference by the four most problematic species of Australian crops.

Seed Retention of Grass Weeds at Wheat Harvest in the Pacific Northwest

Weed Science ◽  
2020 ◽  
pp. 1-32
Author(s):  
Carolina San Martín ◽  
Mark E Thorne ◽  
Jennifer A Gourlie ◽  
Drew J Lyon ◽  
Judit Barroso
Keyword(s):  
Pacific Northwest ◽  
Seed Production ◽  
Secale Cereale ◽  
Bromus Tectorum ◽  
Wheat Crop ◽  
Weed Seed ◽  
Weed Species ◽  
Seed Shattering ◽  
Seed Retention ◽  
The Pacific

Abstract Harvest weed seed control (HWSC) may control problematic weeds by decreasing contributions to the weed seed bank. However, HWSC practices will not be effective if plants have shed a great part of their seeds before harvest, or if a low proportion of seed production is retained at a height that enables collection during harvest. The seed shattering pattern of several weed species was evaluated over three growing seasons to determine their potential to be controlled with HWSC in the Pacific Northwest (PNW). The studied weed species were downy brome (Bromus tectorum L.), feral rye (Secale cereale L.), Italian ryegrass [Lolium perenne ssp. multiflorum (Lam.) Husnot,], and rattail fescue [Vulpia myuros (L.) C.C. Gmel.]. Seed retention at harvest, seed production, and plant height differed among species, locations, and years. Environmental conditions influenced seed shattering patterns, particularly the time plants started to shatter seeds and the rate of the shattering. Agronomic factors such as herbicide use, inter-row space, or crop height/vigor also seemed to affect shattering patterns and seed production, but more specific studies must be conducted to determine their individual effects. Bromus tectorum, L. perenne ssp. multiflorum, and V. myuros had an average seed retention at harvest of less than 50%. In addition, the low seed retention height of V. myuros makes this species a poor candidate for HWSC. Secale cereale had average seed retention at harvest greater than 50% and seed retention height was greater than 30 cm. The variability of seed retention in different species will make the efficacy of HWSC practices species and environment dependent in PNW winter wheat cropping systems. Harvesting the wheat crop as early as possible will be crucial to the success of HWSC.

Harvest Weed Seed Control Systems are Similarly Effective on Rigid Ryegrass

2017 ◽  
Vol 31 (2) ◽  
pp. 178-183 ◽  
Author(s):  
Michael J. Walsh ◽  
Charlotte Aves ◽  
Stephen B. Powles
Keyword(s):  
Control Systems ◽  
Seed Production ◽  
Cropping Systems ◽  
Vital Role ◽  
Wild Radish ◽  
Weed Seed ◽  
Wild Oats ◽  
Rigid Ryegrass ◽  
Annual Weeds ◽  
Crop Maturity

Harvest weed seed control (HWSC) systems have been developed to exploit the high proportions of seed retained at maturity by the annual weeds rigid ryegrass, wild radish, bromegrass, and wild oats. To evaluate the efficacy of HWSC systems on rigid ryegrass populations, three systems, the Harrington Seed Destructor (HSD), chaff carts, and narrow-windrow burning were compared at 24 sites across the western and southern wheat production regions of Australia. HWSC treatments were established at harvest (Nov. – Dec.) in wheat crops with low to moderate rigid ryegrass densities (1 to 26 plants m−2). Rigid ryegrass counts at the commencement of the next growing season (Apr. – May) determined that HWSC treatments were similarly effective in reducing emergence. Chaff carts, narrow-windrow burning, or HSD systems act similarly on rigid ryegrass seed collected during harvest to deliver substantial reductions in subsequent rigid ryegrass populations by restricting seedbank inputs. On average, population densities were reduced by 60%, but there was considerable variation between sites (37 to 90%) as influenced by seed production and the residual seedbank. Given the observed high rigid ryegrass seed production levels at crop maturity it is clear that HWSC has a vital role in preventing seedbank inputs in Australian conservation cropping systems.

Varying responses of field-selected herbicide-resistant rigid ryegrass (Lolium rigidum) populations to combinations of phorate with PPI herbicides

Weed Science ◽  
2020 ◽  
Vol 68 (4) ◽  
pp. 367-372
Author(s):  
David J. Brunton ◽  
Peter Boutsalis ◽  
Gurjeet Gill ◽  
Christopher Preston
Keyword(s):  
Fold Increase ◽  
Acid Synthesis ◽  
Resistance Mechanisms ◽  
Lolium Rigidum ◽  
Cytochrome P450 Enzymes ◽  
Long Chain Fatty Acid ◽  
Herbicide Resistant ◽  
Rigid Ryegrass ◽  
Sites Of Action

AbstractOrganophosphate insecticides, which have the capacity to inhibit specific herbicide-degrading (cytochrome P450) enzymes, have been used to explore metabolic herbicide-resistance mechanisms in weeds. This study investigates the response of seven field-selected rigid ryegrass (Lolium rigidum Gaudin) populations to herbicides from three different sites of action in the presence or absence of the P450 inhibitor phorate. Phorate antagonized the thiocarbamate herbicides triallate and prosulfocarb (8-fold increase in LD50) in multiple resistant L. rigidum populations with resistance to three different site-of-action herbicides. In contrast, phorate synergized trifluralin and propyzamide in some populations, reducing the LD50 by 50%. Conversely, treatment with phorate had no significant effect on the LD50 for S-metolachlor or pyroxasulfone (inhibitors of very-long-chain fatty-acid synthesis). Phorate has diverse effects that are herbicide and population dependant in field-selected L. rigidum, suggesting P450 involvement in the metabolism of trifluralin and failure to activate thiocarbamate herbicides in these populations. This research highlights the need for implementation of diverse approaches other than herbicide alone as part of a long-term integrated strategy to reduce the likelihood of metabolism-based resistance to PPI herbicides in L. rigidum.

Interference of turnipweed (Rapistrum rugosum) and Mexican pricklepoppy (Argemone mexicana) in wheat

Weed Science ◽  
2019 ◽  
Vol 67 (6) ◽  
pp. 666-672 ◽  
Author(s):  
Sudheesh Manalil ◽  
Bhagirath Singh Chauhan
Keyword(s):  
Yield Loss ◽  
Field Studies ◽  
Suppressive Effect ◽  
Wheat Crop ◽  
Yield Reduction ◽  
Weed Seed ◽  
Argemone Mexicana ◽  
Seed Retention ◽  
Exponential Decay Model ◽  
Rapistrum Rugosum

AbstractTurnipweed [Rapistrum rugosum (L.) All.] and Mexican pricklepoppy (Argemone mexicana L.) are increasingly prevalent in the northern cropping regions of Australia. The effect of different densities of these two weeds was examined for their potential to cause yield loss in wheat (Triticum aestivum L.) through field studies in 2016 and 2017. There was 72% to 78% yield reduction in wheat due to competition from R. rugosum. Based on the exponential decay model, 18.2 and 24.3 plants m−2 caused a yield reduction of 50% in 2016 and 2017, respectively. Rapistrum rugosum produced a maximum of 32,042 and 29,761 seeds m−2 in 2016 and 2017, respectively. There was 100% weed seed retention at crop harvest. Competition from A. mexicana resulted in a yield loss of 17% and 22% in 2016 and 2017, respectively; however, plants failed to set seeds due to intense competition from wheat. Among the yield components, panicles per square meter and grains per panicle were affected by weed competition. The studies indicate a superior competitiveness of R. rugosum in wheat and a suppressive effect of wheat on A. mexicana. The results indicate that a wheat crop can be included in crop rotation programs where crop fields are infested with A. mexicana. High seed retention in R. rugosum indicates the possibility to manage this weed through seed catching and harvest weed seed destruction.

Control of thiocarbamate-resistant rigid ryegrass (Lolium rigidum) in wheat in southern Australia

2019 ◽  
Vol 34 (1) ◽  
pp. 19-24
Author(s):  
David J. Brunton ◽  
Peter Boutsalis ◽  
Gurjeet Gill ◽  
Christopher Preston
Keyword(s):  
Dose Response ◽  
Field Experiments ◽  
Seed Set ◽  
Wheat Yield ◽  
South Australia ◽  
Control Treatment ◽  
Lolium Rigidum ◽  
Weed Seed ◽  
Site Of Action ◽  
Rigid Ryegrass

AbstractTwo field experiments were conducted during 2018 at Paskeville and Arthurton, South Australia, to identify effective herbicide options for the control of thiocarbamate-resistant rigid ryegrass in wheat. Dose–response experiments confirmed resistance in both field populations (T1 and A18) of rigid ryegrass to triallate, prosulfocarb, trifluralin, and pyroxasulfone. T1 and A18 were 17.9- and 20-fold more resistant to triallate than susceptible SLR4. The level of resistance detected in T1 to prosulfocarb (5.9-fold) and pyroxasulfone (4-fold) was lower compared to A18, which displayed 12.1- and 7.8-fold resistance to both herbicides, respectively. Despite resistance, the mixture of two different preplant-incorporated (PPI) site-of-action herbicides improved rigid ryegrass control and wheat yield compared to a single PPI herbicide only. Prosulfocarb + triallate and prosulfocarb + S-metolachlor + triallate did not reduce rigid ryegrass seed set when compared to prosulfocarb applied alone at the higher rate (2,400 g ai ha–1). Pyroxasulfone + triallate PPI followed by glyphosate (1,880 g ai ha-1) as a weed seed set control treatment reduced rigid ryegrass seed production by 93% and 95% at both sites, respectively. These herbicides also significantly improved grain yield of wheat at Paskeville (22%) and Arthurton (38%) compared to the untreated.

Ameliorating soil acidity–reduced growth of rigid ryegrass (Lolium rigidum) in wheat

Weed Science ◽  
2020 ◽  
Vol 68 (4) ◽  
pp. 426-433
Author(s):  
Catherine P. D. Borger ◽  
Gaus Azam ◽  
Chris Gazey ◽  
Andrew van Burgel ◽  
Craig A. Scanlan
Keyword(s):  
Seed Production ◽  
Competitive Ability ◽  
Soil Acidity ◽  
Tiller Number ◽  
Wheat Crop ◽  
Initial Growth ◽  
Lolium Rigidum ◽  
Controlled Conditions ◽  
Lime Application ◽  
Rigid Ryegrass

AbstractEstimates indicate that 30% of land surface globally is affected by soil acidity, influencing agricultural production. Application of lime increases soil pH and improves crop growth. We tested the hypothesis that liming will reduce rigid ryegrass (Lolium rigidum Gaudin) growth by improving the competitive ability of the crop. Experiments at Merredin and Wongan Hills in Western Australia indicated that application of lime in previous years reduced L. rigidum density, biomass, and seed production in wheat (Triticum aestivum L.) crops in 2018. At Merredin, L. rigidum seed production in 2018 was reduced from 9,390 to 2,820 seeds m−2, and wheat tiller number and yield was increased, following lime application of 0 to 6,000 kg ha−1 in 2016. At Wongan Hills, lime application of 4,000 kg ha−1 in 1994 reduced seed production in the 2018 wheat crop from 4,708 to 1,610 seeds m−2, and application of 3,000 kg ha−1 of lime in 2014 reduced seed production from 3,959 to 921 seeds m−2 in 2018. Again, lime increased wheat tiller number, but not yield. A screen house experiment (in controlled conditions) indicated that lime application increased the initial growth of both L. rigidum and wheat seedlings. This supports the conclusion that reduced L. rigidum growth and seed production in the field resulted from increased competitive ability of the crop, rather than any direct and detrimental impact of lime on L. rigidum growth. Incorporation of lime reduced initial emergence of L. rigidum in controlled conditions, with L. rigidum seeds at a uniform depth, and in the field experiments in situations of high weed density, with seeds buried by the incorporation process. Nationally, the revenue loss from residual L. rigidum in crop is A$93 million per year. The current research confirms that application of lime will increase the competitive ability of crops growing in regions with acidic soils.

scholarly journals Seed shattering phenology at soybean harvest of economically important weeds in multiple regions of the United States. Part 1: broadleaf species

Weed Science ◽  
2020 ◽  
pp. 1-29
Author(s):  
Lauren M. Schwartz-Lazaro ◽  
Lovreet S. Shergill ◽  
Jeffrey A. Evans ◽  
Muthukumar V. Bagavathiannan ◽  
Shawn C. Beam ◽  
...  
Keyword(s):  
The United States ◽  
Ambrosia Artemisiifolia ◽  
Retention Rates ◽  
Weed Species ◽  
Physiological Maturity ◽  
Seed Retention ◽  
Northern Latitudes ◽  
Multiple Regions ◽  
Broadleaf Species ◽  
Crop Maturity

Abstract Potential effectiveness of harvest weed seed control (HWSC) systems depends upon seed shatter of the target weed species at crop maturity, enabling its collection and processing at crop harvest. However, seed retention likely is influenced by agroecological and environmental factors. In 2016 and 2017, we assessed seed shatter phenology in thirteen economically important broadleaf weed species in soybean [Glycine max (L.) Merr.] from crop physiological maturity to four weeks after physiological maturity at multiple sites spread across fourteen states in the southern, northern, and mid-Atlantic U.S. Greater proportions of seeds were retained by weeds in southern latitudes and shatter rate increased at northern latitudes. Amaranthus species seed shatter was low (0 to 2%), whereas shatter varied widely in common ragweed (Ambrosia artemisiifolia L.) (2 to 90%) over the weeks following soybean physiological maturity. Overall, the broadleaf species studied shattered less than ten percent of their seeds by soybean harvest. Our results suggest that some of the broadleaf species with greater seed retention rates in the weeks following soybean physiological maturity may be good candidates for HWSC.

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