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.

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.

scholarly journals Influence of crop rotation, tillage, and management inputs on weed seed production

Weed Science ◽  
1999 ◽  
Vol 47 (2) ◽  
pp. 175-183 ◽  
Author(s):  
George O. Kegode ◽  
Frank Forcella ◽  
Sharon Clay
Keyword(s):  
Seed Production ◽  
Crop Rotation ◽  
Crop Production ◽  
Conservation Tillage ◽  
Farming Systems ◽  
Crop Rotations ◽  
Weed Seed ◽  
Weed Species ◽  
Weed Seeds ◽  
Ridge Tillage

Approaches to crop production that successfully reduce weed seed production can benefit farming systems by reducing management inputs and costs. A 5-yr rotation study was conducted in order to determine the effects that interactions between crop rotation, tillage, and amount of herbicide and fertilizer (management inputs) have on annual grass and broad-leaved weed seed production and fecundity. There were 10 crop rotation and tillage system combinations and three levels of management inputs (high, medium, and low). Green and yellow foxtail were the major weed species, and together they yielded between 76 and 93% of collected weed seeds. From 1990 to 1994, average grass weed seed productions were 7.3 by 103, 3.7 by 1036.1 by 103and 5.7 by 103seeds m−-2, whereas average broad-leaved weed seed productions were 0.4 by 103, 0.4 by 103, 1.4 by 103, and 0.4 by 103seeds m−-2in crop rotations using conventional tillage (moldboard plow), conservation tillage, no tillage, and ridge tillage, respectively. Crop rotations using conventional or ridge tillage consistently produced more grass and broad-leaved weed seeds, especially in low-input plots. There was little difference in weed seed production among input levels for crop rotations using conservation tillage. Comparing rotations that began and ended with a corn crop revealed that by increasing crop diversity within a rotation while simultaneously reducing the amount of tillage, significantly fewer grass and broad-leaved weed seeds were produced. Among the rotations, grass and broad-leaved weed fecundity were highly variable, but fecundity declined from 1990 to 1994 within each rotation, with a concomitant increase in grass and broad-leaved weed density over the same period. Crop rotation in combination with reduced tillage is an effective way of limiting grass and broad-leaved weed seed production, regardless of the level of management input applied.

scholarly journals Seed shattering phenology at soybean harvest of economically important weeds in multiple regions of the United States. Part 2: grass species

Weed Science ◽  
2020 ◽  
pp. 1-19
Author(s):  
Lauren M. Schwartz-Lazaro ◽  
Lovreet S. Shergill ◽  
Jeffery A. Evans ◽  
Muthukumar V. Bagavathiannan ◽  
Shawn C. Beam ◽  
...  
Keyword(s):  
The United States ◽  
Grass Species ◽  
Annual Grass ◽  
Weed Seed ◽  
Weed Species ◽  
Seed Shattering ◽  
Physiological Maturity ◽  
Rate Of Progression ◽  
Multiple Regions ◽  
Grass Weed

Abstract Seed shatter is an important weediness trait on which the efficacy of harvest weed seed control (HWSC) depends. The level of seed shatter in a species is likely influenced by agroecological and environmental factors. In 2016 and 2017, we assessed seed shatter of eight economically important grass weed species in soybean [Glycine max (L.) Merr.] from crop physiological maturity to four weeks after maturity at multiple sites spread across eleven states in the southern, northern, and mid-Atlantic U.S. From soybean maturity to four weeks after maturity, cumulative percent seed shatter was lowest in the southern U.S. regions and increased as the states moved further north. At soybean maturity, the percent of seed shatter ranged from 1 to 70%. That range had shifted to 5 to 100% (mean: 42%) by 25 days after soybean maturity. There were considerable differences in seed shatter onset and rate of progression between sites and years in some species that could impact their susceptibility to HWSC. Our results suggest that many summer annual grass species are likely not ideal candidates for HWSC, although HWSC could substantially reduce their seed output at during certain years.

scholarly journals Verticillium Wilt in Spinach Seed Production

Plant Disease ◽  
2005 ◽  
Vol 89 (1) ◽  
pp. 4-11 ◽  
Author(s):  
Lindsey J. du Toit ◽  
Mike L. Derie ◽  
Pablo Hernandez-Perez
Keyword(s):  
United States ◽  
Pacific Northwest ◽  
Seed Production ◽  
Verticillium Wilt ◽  
Spinacia Oleracea ◽  
Seed Transmission ◽  
The United States ◽  
Male And Female ◽  
Systemic Movement ◽  
The Pacific

There are no previous reports of Verticillium wilt in fresh and processing spinach (Spinacia oleracea) crops in the United States. In 2002, a hybrid spinach seed crop in the Pacific Northwest developed late-season wilt symptoms. Assays of the harvested seed and stock seed of the male and female parents revealed 59.5, 44.0, and 1.5%, respectively, were infected with Verticillium dahliae. Assays of 13 stock or commercial seed lots grown in 2002 and 62 commercial lots harvested in 2003 in Denmark, Holland, New Zealand, and the United States revealed the prevalence of Verticillium spp. in commercial spinach seed. Sixty-eight lots (89%) were infected with Verticillium spp. at incidences ranging from 0.3 to 84.8%. Five spinach seed isolates of V. dahliae were pathogenic on each of three spinach cultivars by root-dip inoculation. V. dahliae was detected on 26.4% of the seed from 7 of 11 inoculated plants but on none of the seed from 6 control plants, demonstrating systemic movement of V. dahliae. Seed-to-seed transmission was also demonstrated by planting naturally infected seed lots. This is the first report of Verticillium wilt of spinach in the primary region of spinach seed production in the United States.

EFFECTS OF TIME OF EMERGENCE, POPULATION DENSITY AND INTERSPECIFIC COMPETITION ON HEMP-NETTLE (Galeopsis tetrahit) SEED PRODUCTION

1989 ◽  
Vol 69 (1) ◽  
pp. 185-194 ◽  
Author(s):  
ANNE LÉGÈRE ◽  
JEAN-MARC DESCHÊNES
Keyword(s):  
Population Density ◽  
Interspecific Competition ◽  
Seed Production ◽  
Unit Area ◽  
Initial Growth ◽  
Weed Seed ◽  
Weed Species ◽  
Crop Species ◽  
Thlaspi Arvense ◽  
Delayed Emergence

Various conditions of intra- and interspecific competition may influence weed seed production thus affecting the extent of seed return to the soil. The objective of this study was to measure the effects of time of emergence, population density, and weed crop interaction on seed production of hemp-nettle (Galeopsis tetrahit) in natural field populations. Hemp-nettle seed production was studied in pure hemp-nettle stands, mixed hemp-nettle-stinkweed (Thlaspi arvense) stands, hemp-nettle-crop stands, and hemp-nettle-stinkweed-crop stands. Crop species used were alfalfa (Medicago sativa) and oats (Avena sativa). In pure hemp-nettle stands, delayed emergence and high population density reduced seed production of individual hemp-nettle plants. Hemp-nettle seed production per unit area was comparable for all but the lowest population density. Stink-weed population densities up to 200 plants m−2 had no consistent effect on average seed production of individual hemp-nettle plants. Seed production of individual plants was scarcely affected by the presence of alfalfa whereas it was largely reduced in the presence of the oat crop. Oats were usually more competitive than alfalfa, the latter crop being disadvantaged by slow initial growth. Hemp-nettle was not as prolific as other weed species but still produced enough seeds to reinfest the soil, even under highly competitive conditions.Key words: Hemp-nettle, Galeopsis tetrahit, seed production, weed reproduction

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.

Integrated Strategies for Management of Perennial Weeds

2016 ◽  
Vol 9 (2) ◽  
pp. 148-158 ◽  
Author(s):  
Timothy W. Miller
Keyword(s):  
Pacific Northwest ◽  
Integrated Management ◽  
Integrated Control ◽  
Control Program ◽  
The United States ◽  
Management Control ◽  
Weed Species ◽  
Perennial Weed ◽  
Integrated Strategies ◽  
The Pacific

Multiple weed control strategies employed in combination can often aid the successful management of perennial weed species. This review article provides examples of integrated control programs that could aid in the management of several invasive perennial weed species that are problematic in the Pacific Northwest and elsewhere in North America. The development of an integrated management control program for wild chervil, a relatively recent invader to the Pacific Northwest of the United States and adjacent Canada, provides an example for this process. Through use of mechanical (mowing and tillage), cultural (establishment of competitive vegetation), and chemical (specific herbicides) strategies, control of this short-lived perennial species was greatly improved as compared to foliar herbicide applications alone. Such integrated strategies have been shown to enhance control of many perennial weed species, while potentially reducing the amount of herbicide applied, lessening the possibility of injury to adjacent desirable vegetation and increasing the stability of the ecological community at the site.

scholarly journals Influence of Postemergence Dicamba/Glyphosate Timing and Inclusion of Acetochlor as a Layered Residual on Weed Control and Soybean Yield

2021 ◽  
Vol 3 ◽  
Author(s):  
Sarah Striegel ◽  
Maxwel C. Oliveira ◽  
Ryan P. DeWerff ◽  
David E. Stoltenberg ◽  
Shawn P. Conley ◽  
...  
Keyword(s):  
Grain Yield ◽  
Weed Control ◽  
Seed Production ◽  
Developmental Stages ◽  
Weed Seed ◽  
Weed Species ◽  
Soybean Yield ◽  
Density Reduction ◽  
Giant Ragweed ◽  
Residual Herbicide

Roundup Ready 2 Xtend® [glyphosate- and dicamba-resistant (DR)] soybean is a novel trait option for postemergence (POST) control of herbicide-resistant broadleaf weeds in soybean. With increased use of labeled dicamba products POST in DR soybean and recommendations to include a soil-residual herbicide POST (e.g., layered residual approach), research on how combinations of these approaches influence weed control, weed seed production, and soybean grain yield is warranted. The objective of this research was to evaluate the effects of (1) flumioxazin applied preemergence (PRE) followed by (fb) dicamba plus glyphosate applied POST at different crop developmental stages and (2) acetochlor POST as a layered residual approach on weed control, weed seed production, and soybean yield to determine the optimal POST timing in DR soybean. A field study was conducted in Wisconsin at three sites in 2018 and four sites in 2019 to evaluate flumioxazin (43.4 g ai ha−1, WDG 51%) PRE fb dicamba (560 g ae ha−1, SL) plus glyphosate (1,101 g ae ha−1, SL) POST in DR soybean at three stages: early-POST (EPOST, V1-V2), mid-POST (MPOST, V3-V4), and late-POST (LPOST, V5-V6/R1) with or without a soil-residual herbicide POST (acetochlor, 1,262 g ai ha−1, ME). Weed community composition was site-specific; difficult-to-control broadleaf species included giant ragweed (Ambrosia trifida L.) and waterhemp [Amaranthus tuberculatus (Moq.) J.D. Sauer]. Dicamba plus glyphosate applied MPOST and LPOST provided greater control, weed biomass reduction, and density reduction of giant ragweed and waterhemp when compared with EPOST treatments. Giant ragweed and waterhemp had not reached 100% cumulative emergence at EPOST, and plants that emerged after EPOST produced seed. There was some benefit to including acetochlor as a layered residual at EPOST as indicated by a residual by POST timing interaction for waterhemp density reduction. Complete waterhemp control was not attained at one site-year. For remaining site-years, dicamba plus glyphosate applied MPOST (V3-V4) provided season-long weed control, reduced weed seed production, and optimized soybean grain yield compared with other POST treatments. Results highlight the importance of timely POST applications and suggest utilization of a POST layered residual needs to be timed appropriately for the window of active weed species emergence.

scholarly journals REVIEW OF THE INFLUENCE OF CROP ROTATION AND PRIMARY TILLAGE OPERATIONS ON WEED SEED BANK

2021 ◽  
Vol 9 (7) ◽  
pp. 407-421
Author(s):  
Nawal Al-Hajaj
Keyword(s):  
Seed Production ◽  
Crop Rotation ◽  
Seed Bank ◽  
Seedling Recruitment ◽  
Crop Productivity ◽  
Crop Rotations ◽  
Weed Seed ◽  
Weed Species ◽  
Primary Tillage ◽  
Weed Emergence

In this study, we reviewed weed seed bank dynamic and main agriculture operations to come up with the weed seed management modeling designed to increase crop productivity by removing weed competition. Weed contributing with 10% loss of total global grain production. Weed seed bank regulate by five demographic processes seedling recruitment and survival, seed production, dispersal and seed survival in soil. The main agriculture operations that interference with weed seed bank are crop rotation and primary tillage. Tillage systems affect weed emergence, management, and seed production; therefore, changing tillage practices changes the composition, vertical distribution, and density of weed seed bank in agricultural soils. Weed species vary in their response to various crop rotations, due to the variability of weed-crop competition in their relative capacity to capture growth–limiting resources. Crop rotations affect weed emergence, management, composition, and density of weed seed bank. Finally, the study suggests elevating crop competitiveness against weeds, through a combination of crop rotation and reduce_ zero tillage, has strong potential to reduce weed-induced yield losses in crop.

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