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.

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.

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.

scholarly journals Tall Waterhemp (Amaranthus tuberculatus) and Palmer amaranth (Amaranthus palmeri) Seed Production and Retention at Soybean Maturity

2016 ◽  
Vol 30 (1) ◽  
pp. 284-290 ◽  
Author(s):  
Lauren M. Schwartz ◽  
Jason K. Norsworthy ◽  
Bryan G. Young ◽  
Kevin W. Bradley ◽  
Greg R. Kruger ◽  
...  
Keyword(s):  
Seed Production ◽  
Plant Size ◽  
Palmer Amaranth ◽  
Weed Seed ◽  
Great Opportunity ◽  
Weed Biomass ◽  
Seed Retention ◽  
Loose Soil ◽  
Soil Seedbank ◽  
Total Seed

Two of the most problematicAmaranthusspecies in soybean production today are tall waterhemp and Palmer amaranth. This study determined the percentage of tall waterhemp and Palmer amaranth seed that was retained by the weed at soybean maturity to assess the likelihood of using at-harvest weed seed control tactics for soil seedbank management. Palmer amaranth plants were collected from fields in Arkansas, Tennessee, Illinois, Missouri, and Nebraska, and tall waterhemp plants were collected from fields in Nebraska, Missouri, Wisconsin, and Illinois. Collected plants were assessed for at-harvest weed seed retention in 2013 and 2014. Within 1 wk of soybean maturity,Amaranthusplants were harvested and the loose soil and debris beneath the plants were swept into a pan with a hand broom to collect any shattered seed. Percent seed retention ranged from 95 to 100% for all states both years, regardless of species. There was a strong correlation between weed biomass (g) and total seed production (no. plant−1) in that the larger the plant, the more seeds it produced. However, there was no correlation between percent seed retention and weed biomass, which indicates that regardless of plant size and likely time of emergence, seed retention is high at the time of crop maturity. Overall, this study demonstrated that there is great opportunity for Palmer amaranth and tall waterhemp seed capture or destruction at soybean harvest. It is likely that nearly all of the seeds produced for bothAmaranthusspecies passes through the combine during harvest to be returned to the soil seedbank. Thus, there is continued need for research focused on developing and testing harvest weed seed control tactics that aim at reducing the soil seedbank and lowering risks for evolution of herbicide resistance.

Predicting the competitive effects of weed and crop density on weed biomass, weed seed production and crop yield in wheat

Weed Research ◽  
2006 ◽  
Vol 35 (4) ◽  
pp. 265-278 ◽  
Author(s):  
B. J. WILSON ◽  
K. J. WRIGHT ◽  
P. BRAIN ◽  
M. CLEMENTS ◽  
E. STEPHENS
Keyword(s):  
Seed Production ◽  
Crop Yield ◽  
Weed Seed ◽  
Weed Biomass ◽  
Competitive Effects ◽  
Crop Density

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.

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.

Junglerice (Echinochloa colona) and feather fingergrass (Chloris virgata) seed production and retention at sorghum maturity

2019 ◽  
Vol 34 (2) ◽  
pp. 272-276 ◽  
Author(s):  
Gulshan Mahajan ◽  
Michael Walsh ◽  
Bhagirath S. Chauhan
Keyword(s):  
Seed Production ◽  
Production Potential ◽  
Weed Biomass ◽  
Positive Correlation ◽  
Seed Retention ◽  
Limited Opportunity ◽  
Resistance To Herbicides ◽  
Crop Harvest ◽  
Chloris Virgata ◽  
Crop Maturity

AbstractIn Australia, junglerice and feather fingergrass are problematic weeds in sorghum. The high seed production potential of these weeds increases their seedbank in the soil and makes weed control practices more difficult and expensive, particularly when weeds have evolved resistance to herbicides. A study was conducted to evaluate the seed production and seed retention behavior of junglerice and feather fingergrass at sorghum crop maturity following four transplanting times: 0, 2, 4, and 6 wk after sorghum emergence. Averaged across years, junglerice and feather fingergrass produced 4,060 and 5,740 seeds plant-1, respectively,when they were transplanted with the emergence of a sorghum crop. Seed retention ranged from 42% to 56% for junglerice and 67% to 75% for feather fingergrass when these weeds were transplanted from 0 to 4 wk after crop emergence. A positive correlation (r = 0.75 for junglerice; r = 0.44 for feather fingergrass) was found between seed production and weed biomass in both weeds, indicating that larger plants produced more seeds than smaller plants. However, no correlation was found between weed biomass and seed retention for junglerice. A weak positive correlation (r = 0.44) was found between feather fingergrass biomass and percent seed retention, indicating that seed retention was greater in larger plants compared with smaller plants. Our results suggest that feather fingergrass is a good candidate for harvest weed seed control (HWSC) tactics if crop harvest is timely. There is limited opportunity to use HWSC tactics for targeting junglerice seeds in sorghum crops, because most seeds dispersed before crop maturity. Additional research is required to evaluate seed retention levels of these weeds in other summer crops such as corn and soybean to determine the potential for HWSC for management of these species.

Interference and Seed Production by Common Lambsquarters (Chenopodium album) in Soybeans (Glycine max)

Weed Science ◽  
1990 ◽  
Vol 38 (2) ◽  
pp. 113-118 ◽  
Author(s):  
S. Kent Harrison
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
Chenopodium Album ◽  
Soybean Seed ◽  
Dry Weight ◽  
Threshold Level ◽  
Yield Reduction ◽  
Significant Treatment ◽  
Weed Biomass ◽  
Common Lambsquarters

Multiple regression and response surface plots were used to analyze the effects of common lambsquarters population density and interference duration on weed growth and soybean seed yield. Under favorable growing conditions in 1986, weed biomass production at all population densities and interference durations was four to five times that produced in 1987, under less favorable conditions. However, there was no significant treatment by year interaction for soybean seed yield reduction by common lambsquarters, and production of each kg/ha weed biomass resulted in an average soybean yield reduction of 0.26 kg/ha. Utilizing 5% yield loss as an arbitrary threshold level, the regression equation predicted a common lambsquarters density threshold of 2 plants/m of row for 5 weeks of interference after crop emergence and 1 plant/m of row for 7 weeks. Seed production by individual common lambsquarters plants was highly correlated (r=0.92) with weed dry weight, and seed production ranged from 30 000 to 176 000 seeds/plant.

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