scholarly journals Enhanced weed‐crop competition effects on growth and seed production of herbicide‐resistant and herbicide‐susceptible annual sowthistle ( Sonchus oleraceus )

2020 ◽  
Vol 20 (2) ◽  
pp. 38-46
Author(s):  
Ahmadreza Mobli ◽  
Sahil ◽  
Rajpaul Yadav ◽  
Bhagirath S. Chauhan
Keyword(s):  
Seed Production ◽  
Herbicide Resistant ◽  
Sonchus Oleraceus ◽  
Competition Effects ◽  
Crop Competition

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.

Modeling Population Dynamics of Kochia (Bassia scoparia) in Response to Diverse Weed Control Options

Weed Science ◽  
2019 ◽  
Vol 67 (1) ◽  
pp. 57-67 ◽  
Author(s):  
O. Adewale Osipitan ◽  
J. Anita Dille ◽  
Muthukumar V. Bagavathiannan ◽  
Stevan Z. Knezevic
Keyword(s):  
Population Dynamics ◽  
Population Growth ◽  
Weed Control ◽  
Seed Production ◽  
Seedling Recruitment ◽  
Control Strategies ◽  
Effective Control ◽  
Parameter Estimates ◽  
Herbicide Resistant

AbstractKochia [Bassia scoparia(L.) A. J. Scott] is a problematic weed species across the Great Plains, as it is spreading fast and has developed herbicide-resistant biotypes. It is imperative to understand key life-history stages that promote population expansion ofB. scopariaand control strategies that would provide effective control of these key stages, thereby reducing population growth. Diversifying weed control strategies has been widely recommended for the management of herbicide-resistant weeds. Therefore, the objectives of this study were to develop a simulation model to assess the population dynamics ofB. scopariaand to evaluate the effectiveness of diverse weed control strategies on long-term growth rates ofB. scopariapopulations. The model assumed the existence of a glyphosate-resistant (GR) biotype in theB. scopariapopulation, but at a very low proportion in a crop rotation that included glyphosate-tolerant corn (Zea maysL.) and soybean [Glycine max(L.) Merr.]. The parameter estimates used in the model were obtained from various ecological and management studies onB. scoparia. Model simulations indicated that seedling recruitment and survival to seed production were more important than seedbank persistence forB. scopariapopulation growth rate. Results showed that a diversified management program, including glyphosate, could provide excellent control ofB. scopariapopulations and potentially eliminate already evolved GRB. scopariabiotypes within a given location. The most successful scenario was a diverse control strategy that included one or two preplant tillage operations followed by preplant or PRE application of herbicides with residual activities and POST application of glyphosate; this strategy reduced seedling recruitment, survival, and seed production during the growing season, with tremendous negative impacts on long-term population growth and resistance risk inB. scoparia.

scholarly journals Effective Preemergence and Postemergence Herbicide Programs for Kochia Control

2015 ◽  
Vol 29 (1) ◽  
pp. 24-34 ◽  
Author(s):  
Vipan Kumar ◽  
Prashant Jha
Keyword(s):  
Field Experiments ◽  
Agricultural Research ◽  
Residual Activity ◽  
Acetolactate Synthase ◽  
Test Site ◽  
Herbicide Resistant ◽  
Greenhouse Study ◽  
Chemical Fallow ◽  
Herbicide Programs ◽  
Crop Competition

Field experiments were conducted in 2011 through 2013 at the MSU Southern Agricultural Research Center near Huntley, MT, to evaluate the effectiveness of various PRE and POST herbicide programs for kochia control in the absence of a crop. PRE herbicides labeled for corn, grain sorghum, soybean, wheat/barley, and/or in chemical fallow were applied at recommended field-use rates. Acetochlor + atrazine,S-metolachlor + atrazine + mesotrione, and sulfentrazone applied PRE provided ≥91% control of kochia at 12 wk after treatment (WAT). Metribuzin, metribuzin + linuron, and pyroxasulfone + atrazine PRE provided 82% control at 12 WAT. PRE control with acetochlor + flumetsulam + clopyralid, pyroxasulfone alone, and saflufenacil + 2,4-D was ≤23% at 12 WAT. Paraquat + atrazine, paraquat + linuron, and paraquat + metribuzin controlled kochia ≥98% at 5 WAT. POST control with bromoxynil + fluroxypyr, paraquat, tembotrione + atrazine, and topramezone + atrazine treatments averaged 84% at 5 WAT, and did not differ from glyphosate. Control with POST-applied bromoxynil + pyrasulfotole, dicamba, diflufenzopyr + dicamba + 2,4-D, saflufenacil, saflufenacil + 2,4-D, saflufenacil + linuron was 67 to 78% at 5 WAT. Because of the presence of kochia resistant to acetolactate synthase-inhibiting herbicides at the test site, cloransulam-methyl was not a viable option for kochia control. In a separate greenhouse study, kochia accessions showed differential response to the POST herbicides (labeled for corn or soybean) tested. Tembotrione + atrazine, topramezone + atrazine, lactofen, or fomesafen effectively controlled the glyphosate-resistant kochia accession tested. Growers should utilize these effective PRE- or POST-applied herbicide premixes or tank mixtures (multiple modes of action) to control herbicide-resistant kochia accessions in the field. PRE herbicides with 8 wk of soil-residual activity on kochia would be acceptable if crop competition were present; however, a follow-up herbicide application may be needed to obtain season-long kochia control in the absence of crop competition.

Dog mustard (Erucastrum gallicum) response to crop competition

Weed Science ◽  
1997 ◽  
Vol 45 (3) ◽  
pp. 397-403
Author(s):  
David A. Wall
Keyword(s):  
Interspecific Competition ◽  
Leaf Area ◽  
Seed Production ◽  
Growth And Development ◽  
Dry Weight ◽  
Field Studies ◽  
Limiting Factor ◽  
Shoot Dry Weight ◽  
Summer Fallow ◽  
Crop Competition

Greenhouse studies suggested that dog mustard was less competitive than wheat, but of similar competitiveness to flax. In field studies, dog mustard growth and development were markedly affected by crop competition. Competition from flax and wheat reduced dog mustard leaf area, shoot dry weight, plant height, and seed production compared with the weed grown on summer-fallow. Dog mustard was a prolific seed producer when grown in the absence of interspecific competition. On summer-fallow, dog mustard produced as many as 79,100 seeds plant−1when moisture was not a limiting factor. However, average seed production was 19,400 and 8000 seeds plant−1in 1994 and 1995, respectively.

Management of ACCase-Inhibiting Herbicide-Resistant Smooth Barley (Hordeum glaucum) in Field Pea with Alternative Herbicides

2016 ◽  
Vol 30 (2) ◽  
pp. 441-447 ◽  
Author(s):  
Lovreet S. Shergill ◽  
Benjamin Fleet ◽  
Christopher Preston ◽  
Gurjeet Gill
Keyword(s):  
Seed Production ◽  
Negative Relationship ◽  
South Australia ◽  
Field Pea ◽  
Forage Yield ◽  
Weed Species ◽  
Herbicide Resistant ◽  
Large Yield ◽  
High Level ◽  
The Impact

Smooth barley is an annual weed species that is infesting crops and pastures in South Australia. Complicating control options is the presence of herbicide-resistant biotypes. A field trial was conducted to identify alternative herbicides for the management of acetyl coenzyme A carboxylase (ACCase)-inhibiting herbicide-resistant smooth barley in field pea. Preplant (PP) soil applications of pyroxasulfone; prosulfocarb plus S-metolachlor; dimethenamid-P; propyzamide; trifluralin alone or with triallate or with diuron; or imazamox applied POST were evaluated for their effectiveness and crop safety. Propyzamide, pyroxasulfone, or imazamox applied POST provided a high level of smooth barley control, did not cause any crop injury, and increased field pea grain or forage yield compared with the nontreated. Furthermore, propyzamide or pyroxasulfone reduced panicle density and seed production in smooth barley, whereas the effectiveness of POST imazamox varied over the two seasons. Dimethenamid-P reduced the impact of smooth barley on field pea yield, but cause stunting, and was less effective than propyzamide, pyroxasulfone, and imazamox in reducing smooth barley seed production. Negative relationship between field pea yield and smooth barley panicle density indicated that smooth barley is highly competitive in field pea crops and can cause large yield losses. The results of this investigation suggest that propyzamide or pyroxasulfone applied PP and imazamox applied POST could be used effectively in the field for the management of ACCase-inhibiting herbicide-resistant smooth barley in South Australia.

Glyphosate-Resistant Palmer Amaranth (Amaranthus palmeri) Morphology, Growth, and Seed Production in Georgia

Weed Science ◽  
2015 ◽  
Vol 63 (1) ◽  
pp. 264-272 ◽  
Author(s):  
Theodore M. Webster ◽  
Timothy L. Grey
Keyword(s):  
United States ◽  
Seed Production ◽  
Growing Season ◽  
Palmer Amaranth ◽  
Competitive Balance ◽  
Potential Growth ◽  
Southeast United States ◽  
Alternative Means ◽  
Soil Seedbank ◽  
Crop Competition

Herbicide-resistant Palmer amaranth has become the most economically detrimental weed of cotton in the southeast United States. With the continual marginalization of potential herbicide tools, research has expanded to include alternative means of affecting future Palmer amaranth populations by altering safe sites and reducing inputs to the seedbank population. The influence of delayed Palmer amaranth establishment on seed production potential has not been investigated in the southeast United States. Studies were conducted to evaluate the influence of time of Palmer amaranth establishment on morphology, growth, and seed production. The experiment was a factorial, with five levels of Palmer amaranth transplanting (0 to 12 wk after cotton planting) and two levels of crop type (cotton and noncrop). In the absence of crop competition, the first cohort of Palmer amaranth produced 446,000 seeds per plant. This potential seed production was reduced 50% when Palmer amaranth plants were established nearly 6 wk later. In contrast, the first Palmer amaranth cohort growing in competition with cotton produced 312,000 seeds, 30% less than was produced in the absence of competition. Interference from cotton shifted time to 50% seed production to nearly 4 wk earlier in the growing season, relative to plants without crop competition. Delayed establishment of Palmer amaranth simulates premature loss of herbicide efficacy and alters the competitive balance between cotton and Palmer amaranth. Although the planting time that resulted in 50% reduction in Palmer amaranth plant height at the end of the season was not affected by the presence of cotton, 50% reduction in plant width and biomass occurred within the first 3.8 wk of the growing season when growing with cotton, more than 4 wk earlier than Palmer amaranth growing without a crop. This suggests that early season weed control programs will have a large effect on Palmer amaranth potential growth and seed production, as well as crop yield. To implement soil seedbank reduction strategies effectively, information on mechanisms that regulate Palmer amaranth persistence in the soil seedbank is needed.

Glyphosate-induced hormesis: impact on seedling growth and reproductive potential of common sowthistle (Sonchus oleraceus)

Weed Science ◽  
2020 ◽  
Vol 68 (6) ◽  
pp. 605-611
Author(s):  
Ahmadreza Mobli ◽  
Amar Matloob ◽  
Bhagirath Singh Chauhan
Keyword(s):  
Seed Production ◽  
Reproductive Potential ◽  
Low Doses ◽  
Sonchus Oleraceus ◽  
Pot Trials ◽  
Plant Maturity ◽  
Number Of Leaves ◽  
Sublethal Doses ◽  
The University ◽  
Herbicide Drift

AbstractIn Australia, glyphosate is widely used in glyphosate-tolerant crops and fallows to control weeds such as common sowthistle (Sonchus oleraceus L.). It has been hypothesized that glyphosate at sublethal doses, as a consequence of herbicide drift, may have a stimulatory effect on S. oleraceus growth. In 2017, pot trials were conducted to evaluate the effect of low doses of glyphosate on growth and seed production of this weed at the Weed Science Screenhouse Facility at the University of Queensland, Australia. At the 4- to 5-leaf stage (3-wk-old rosette), plants were treated with low doses of glyphosate (0 [control], 5, 10, 20, 40, 80, and 800 g ae ha−1), and their responses were recorded until plant maturity. The study was repeated after completion of the first experimental run. An additional glyphosate dose (2.5 g ha−1) was added in the second run. The low doses of glyphosate (<40 g ha−1) caused a significant increase in S. oleraceus plant height and number of leaves compared with the no-glyphosate treatment. The highest stimulatory effect was observed at 5 g ha−1. At 5 g ha−1 glyphosate, S. oleraceus seed production increased by 154% and 101% in the first and second experimental runs, respectively, compared with the no-glyphosate treatment. The results of this study suggest that the sublethal doses of glyphosate produced hormetic effects on growth and seed production of S. oleraceus that changed the dynamics of weed–crop competition.

The response of glyphosate-resistant and glyphosate-susceptible biotypes of annual sowthistle (Sonchus oleraceus) to mungbean density

Weed Science ◽  
2019 ◽  
Vol 67 (6) ◽  
pp. 642-648 ◽  
Author(s):  
Ahmadreza Mobli ◽  
Amar Matloob ◽  
Bhagirath Singh Chauhan
Keyword(s):  
Seed Production ◽  
Weed Management ◽  
Vigna Radiata ◽  
Competitive Ability ◽  
Management Strategies ◽  
Stand Density ◽  
Sonchus Oleraceus ◽  
Crop Density ◽  
Crop Stand ◽  
Number Of Seeds

AbstractAnnual sowthistle (Sonchus oleraceus L.) is a major weed of mungbean crops in Australia. Resistance in this weed to several herbicide groups is a challenging issue for its management. Hence, cultural weed management strategies, such as increasing the crop competitive ability through increased stand density, should be considered to reduce reliance on herbicides. It was hypothesized that a competitive crop stand may reduce the growth and seed production of S. oleraceus. Two pot studies were conducted, and each study was repeated once. The first study evaluated the effect of different mungbean [Vigna radiata (L.) R. Wilczek] densities (0, 82, 164, 246, and 328 plants m−2) on S. oleraceus growth and seed production, while the second study focused on glyphosate-resistant and glyphosate-susceptible biotypes of this weed in competition with densities of 0, 82, and 164 mungbean plants m−2. Although increasing mungbean density from 0 to 82 and 164 plants m−2 reduced S. oleraceus seed production by 55% and 78%, respectively, a large number of seeds were produced, even at the mungbean density of 328 plants m−2 (1,185 seeds plant−1). Both glyphosate-resistant and glyphosate-susceptible biotypes of S. oleraceus responded similarly to the increase in mungbean density. The results of the second study showed that height, leaves, number of inflorescence, and seed production per plant of both glyphosate-resistant and glyphosate-susceptible biotypes were reduced but not suppressed adequately. The glyphosate-resistant biotype produced fewer leaves and less biomass and, consequently, its seed production was 24% less compared with the glyphosate-susceptible biotype in the no-competition treatment. Both biotypes of S. oleraceus produced about 4,000 seeds plant−1 in competition with 164 mungbean plants m−2. The results suggest that crop competition alone cannot provide satisfactory control of S. oleraceus; therefore, for effective and adequate weed management, other practices such as PRE herbicides should be integrated with increased crop density.

Use of herbicide-resistant genic male sterility in hybrid rice seed production

Euphytica ◽  
2007 ◽  
Vol 156 (3) ◽  
pp. 297-303 ◽  
Author(s):  
Sung Soo Kim ◽  
Jae Youn Jung ◽  
Seung Kwon Jeong ◽  
Dong Sun Lee ◽  
Li Juan Chen ◽  
...  
Keyword(s):  
Male Sterility ◽  
Seed Production ◽  
Hybrid Rice ◽  
Rice Seed ◽  
Genic Male Sterility ◽  
Herbicide Resistant
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