Critical Period of Weed Control in Aerobic Rice

Critical period of weed control is the foundation of integrated weed management and, hence, can be considered the first step to design weed control strategy. To determine critical period of weed control of aerobic rice, field trials were conducted during 2010/2011 at Universiti Putra Malaysia. A quantitative series of treatments comprising two components, (a) increasing duration of weed interference and (b) increasing length of weed-free period, were imposed. Critical period was determined through Logistic and Gompertz equations. Critical period varied between seasons; in main season, it started earlier and lasted longer, as compared to off-season. The onset of the critical period was found relatively stable between seasons, while the end was more variable. Critical period was determined as 7–49 days after seeding in off-season and 7–53 days in main season to achieve 95% of weed-free yield, and 23–40 days in off-season and 21–43 days in main season to achieve 90% of weed-free yield. Since 5% yield loss level is not practical from economic view point, a 10% yield loss may be considered excellent from economic view point. Therefore, aerobic rice should be kept weed-free during 21–43 days for better yield and higher economic return.

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The Critical Period for Weed Control (CPWC) in Potato (Solanum tuberosum L.)

Notulae Botanicae Horti Agrobotanici Cluj-Napoca ◽

10.15835/nbha43210031 ◽

2015 ◽

Vol 43 (2) ◽

pp. 355-360 ◽

Cited By ~ 1

Author(s):

Dogan ISIK ◽

Adem AKCA ◽

Emine KAYA ALTOP ◽

Nihat TURSUN ◽

Husrev MENNAN

Keyword(s):

Weed Control ◽

Weed Management ◽

Critical Period ◽

Field Experiments ◽

Yield Loss ◽

Cropping Systems ◽

Control Period ◽

Relative Yield ◽

Yield Data ◽

Weed Interference

Accurate assessment of crop-weed control period is an essential part for planning an effective weed management for cropping systems. Field experiments were conducted during the seasonal growing periods of potato in 2012 and 2013 in Kayseri, Turkey to assess critical period for weed control (CPWC) in potato. A four parameter log-logistic model was used to assist in monitoring and analysing two sets of related, relative crop yield. Data was obtained during the periods of increased weed interference and as a comparison, during weed-free periods. In both years, the relative yield of potato decreased with a longer period of weed-interference whereas increased with increasing length of weed free period. In 2012, the CPWC ranged from 112 to 1014 GDD (Growing Degree Days) which corresponded to 8 to 66 days after crop emergence (DAE) and between 135-958 GDD (10 to 63 DAE) in the following year based on a 5% acceptable yield loss. Weed-free conditions needed to be established as early as the first week after crop emergence and maintained as late as ten weeks after crop emergence to avoid more than 5% yield loss in the potato. The results suggest that CPWC could well assist potato producers to significantly reduce the expense of their weed management programs as well as improving its efficacy.

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Planting date influences critical period of weed control in sweet corn

Weed Science ◽

10.1614/ws-06-005r.1 ◽

2006 ◽

Vol 54 (5) ◽

pp. 928-933 ◽

Cited By ~ 45

Author(s):

Martin M. Williams

Keyword(s):

Weed Control ◽

Weed Management ◽

Critical Period ◽

Sweet Corn ◽

Relative Yield ◽

Planting Date ◽

Integrated Weed Management ◽

Yield Losses ◽

Yield Data ◽

Weed Interference

The critical period for weed control (CPWC) identifies the phase of the crop growth cycle when weed interference results in unacceptable yield losses; however, the effect of planting date on CPWC is not well understood. Field studies were conducted in 2004 and 2005 at Urbana, IL, to determine CPWC in sweet corn for early May (EARLY) and late-June (LATE) planting dates. A quantitative series of treatments of both increasing duration of interference and length of weed-free period were imposed within each planting-date main plot. The beginning and end of the CPWC, based on 5% loss of marketable ear mass, was determined by fitting logistic and Gompertz equations to the relative yield data representing increasing duration of weed interference and weed-free periods, respectively. Weed interference stressed the crop more quickly and to a greater extent in EARLY, relative to LATE. At a 5% yield-loss level, duration of weed interference for 160 and 662 growing-degree days (GDD) from crop emergence marked the beginning of the CPWC for EARLY and LATE, respectively. When maintained weed-free for 320 and 134 GDD, weeds emerging later caused yield losses of less than 5% for EARLY and LATE, respectively. Weed densities exceeded 85 plants m−2for the duration of the experiments and predominant species included barnyardgrass, common lambsquarters, common purslane, redroot pigweed, and velvetleaf. Weed canopy height and total aboveground weed biomass were 300% and 500% higher, respectively, for EARLY compared with LATE. Interactions between planting date and CPWC indicate the need to consider planting date in the optimization of integrated weed management systems for sweet corn. In this study, weed management in mid-June–planted sweet corn could have been less intensive than early May–planted corn, reducing herbicide use and risk of herbicide carryover to sensitive rotation crops.

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Extending the critical period for weed control model to better include weed succession using common sunflower as a mimic weed in high-yielding cotton

Weed Technology ◽

10.1017/wet.2021.91 ◽

2021 ◽

pp. 1-27

Author(s):

Graham W. Charles ◽

Ian N. Taylor

Keyword(s):

Weed Control ◽

Weed Management ◽

Critical Period ◽

Yield Loss ◽

Logistic Function ◽

Integrated Weed Management ◽

Traditional Practice ◽

Crop Planting ◽

Logistic Functions ◽

Weed Emergence

Abstract The critical period for weed control (CPWC) adds value to integrated weed management by identifying the period during which weeds need to be controlled to avoid yield losses exceeding a defined threshold. However, the traditional application of the CPWC does not identify the timing of control needed for weeds that emerge late in the critical period. In this study, CPWC models were developed from field data in high yielding cotton crops during three summer seasons from 2005 to 2008, using the mimic weed; common sunflower, at densities of 2 to 20 plants m−2. Common sunflower plants were introduced at up to 450 growing degree days (GDD) after crop planting and removed at successive 200 GDD intervals after introduction. The CPWC models were described using extended Gompertz and logistic functions that included weed density, time of weed introduction and time of weed removal (logistic function only) in the relationships. The resulting models defined the CPWC for late emerging weeds, identifying a period after weed emergence before weed control was required to prevent yield loss exceeding the yield-loss threshold. Where weeds emerged in sufficient numbers toward the end of the critical period, the model predicted that crop yield loss resulting from competition by these weeds would not exceed the yield-loss threshold until well after the end of the CPWC. These findings support the traditional practice of ensuring weeds are controlled before crop canopy closure, with later weed control inputs used as required.

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Potential yield loss in grain sorghum (Sorghum bicolor) with weed interference in the United States

Weed Technology ◽

10.1017/wet.2020.12 ◽

2020 ◽

Vol 34 (4) ◽

pp. 624-629 ◽

Cited By ~ 1

Author(s):

J. Anita Dille ◽

Phillip W. Stahlman ◽

Curtis R. Thompson ◽

Brent W. Bean ◽

Nader Soltani ◽

...

Keyword(s):

United States ◽

Weed Control ◽

Weed Management ◽

Yield Loss ◽

Science Research ◽

The United States ◽

Grain Sorghum ◽

Control Cost ◽

Potential Yield ◽

Weed Interference

AbstractPotential yield losses in grain sorghum due to weed interference based on quantitative data from the major grain sorghum-growing areas of the United States are reported by the WSSA Weed Loss Committee. Weed scientists and extension specialists who researched weed control in grain sorghum provided data on grain sorghum yield loss due to weed interference in their region. Data were requested from up to 10 individual experiments per calendar year over 10 yr between 2007 and 2016. Based on the summarized information, farmers in Arkansas, Kansas, Missouri, Nebraska, South Dakota, and Texas would potentially lose an average of 37%, 38%, 30%, 56%, 61%, and 60% of their grain sorghum yield with no weed control, and have a corresponding annual monetary loss of US $19 million, 302 million, 7 million, 32 million, 25 million, and 314 million, respectively. The overall average yield loss due to weed interference was estimated to be 47% for this grain sorghum-growing region. Thus, US farmers would lose approximately 5,700 million kg of grain sorghum valued at approximately US $953 million annually if weeds are not controlled. With each dollar invested in weed management (based on estimated weed control cost of US $100 ha−1), there would be a return of US $3.80, highlighting the return on investment in weed management and the importance of continued weed science research for sustaining high grain sorghum yield and profitability in the United States.

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Response of Barley Genotypes to Weed Interference in Australia

Agronomy ◽

10.3390/agronomy10010099 ◽

2020 ◽

Vol 10 (1) ◽

pp. 99 ◽

Cited By ~ 2

Author(s):

Gulshan Mahajan ◽

Lee Hickey ◽

Bhagirath Singh Chauhan

Keyword(s):

Negative Correlation ◽

Weed Management ◽

Field Experiments ◽

Yield Loss ◽

Production Systems ◽

Relative Yield ◽

Organic Production ◽

Integrated Weed Management ◽

Weed Interference ◽

Barley Genotypes

Weed-competitive genotypes could be an important tool in integrated weed management (IWM) practices. However, weed competitiveness is often not considered a priority for breeding high-yielding cultivars. Weed-competitive ability is often evaluated based on weed-suppressive ability (WSA) and weed-tolerance ability (WTA) parameters; however, there is little information on these aspects for barley genotypes in Australia. In this study, the effects of weed interference on eight barley genotypes were assessed. Two years of field experiments were performed in a split-plot design with three replications. Yield loss due to weed interference ranged from 43% to 78%. The weed yield amongst genotypes varied from 0.5 to 1.7 Mg ha−1. Relative yield loss due to weed interference was negatively correlated with WTA and WSA. A negative correlation was also found between WSA and weed seed production (r = −0.72). Similarly, a negative correlation was found between WTA and barley yield in the weedy environment (r = −0.91). The results suggest that a high tillering ability and plant height are desirable attributes for weed competitiveness in the barley genotypes. These results also demonstrated that among the eight barley genotypes, Commander exhibited superior WSA and WTA parameters and therefore, could be used in both low- and high-production systems for weed management. Westminster had a superior WSA parameter. Therefore, it could be used for weed management in organic production systems. These results also implied that genotypic ranking on the basis of WSA and WTA could be used as an important tool in strengthening IWM programs for barley.

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The Critical Period of Weed Control for Lentil in Western Canada

Weed Science ◽

10.1614/ws-d-11-00051.1 ◽

2011 ◽

Vol 59 (4) ◽

pp. 517-526 ◽

Cited By ~ 11

Author(s):

L. K. Fedoruk ◽

E. N. Johnson ◽

S. J. Shirtliffe

Keyword(s):

Weed Control ◽

Critical Period ◽

Inverse Relationship ◽

Yield Loss ◽

Western Canada ◽

Crop Canopy ◽

Herbicide Application ◽

Weed Biomass ◽

Weed Interference ◽

Residual Herbicide

Weed control in lentil is difficult because lentil is a poor competitor with weeds and few POST broadleaf herbicides are available. Imadazolinone-tolerant lentils have more herbicide options, but the optimum timing for herbicide application is not known. The critical period of weed control (CPWC) is the period in a crop's life cycle when weeds must be controlled in order to prevent yield loss. The objective of this research was to determine the CPWC for lentil. We made lentil remain weedy or weed-free from 0 to 11 aboveground nodes to investigate the durations of weed interference and weed-free period, respectively. It was found that lentil has a CPWC beginning at the five-node stage and continuing to the 10-node stage. There was an inverse relationship between weed biomass and lentil yield; that is, lentil yield was highest when weed biomass is minimal. We propose that the CPWC begins when weeds start to accumulate significant biomass and ends with crop canopy closure. Therefore, to maximize lentil yields, growers should consider using a POST residual herbicide that can control weeds during the CPWC.

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Light Quality and the Critical Period for Weed Control in Soybean

Weed Science ◽

10.1614/ws-d-11-00072.1 ◽

2012 ◽

Vol 60 (1) ◽

pp. 86-91 ◽

Cited By ~ 28

Author(s):

Emily Green-Tracewicz ◽

Eric R. Page ◽

Clarence J. Swanton

Keyword(s):

Weed Control ◽

Weed Management ◽

Critical Period ◽

Light Quality ◽

Morphological Changes ◽

Management Strategies ◽

Leaf Number ◽

Integrated Weed Management ◽

Weed Competition ◽

Shade Avoidance

The critical period for weed control (CPWC) is an integral component of integrated weed management strategies. Several studies have defined the CPWC in soybean under varying agronomic conditions, yet none have described the mechanisms involved in crop yield losses caused by weed competition. We hypothesized that under nonresource-limiting conditions, morphological changes resulting from the expression of shade avoidance could be used to define a period of developmental sensitivity to low red-to-far-red ratio (R : FR) that would overlap with the defined CPWC in soybean. Two experiments (a sequential harvest and a weed addition/removal series) were conducted in 2008 and 2009 under controlled environmental conditions to address this hypothesis. Two light-quality treatments were used: (1) high R : FR ratio (i.e., weed-free), and (2) low R : FR ratio (i.e., weedy). The low R : FR ratio treatment induced shade avoidance responses in soybean, which included increases in height, internode length, and the shoot : root ratio, as well as a reduction in biomass accumulation and leaf number. Using the morphological changes in biomass and leaf number observed in the weed addition/removal series, a period of developmental sensitivity to low R : FR was defined between the first trifoliate (V1) and third trifoliate (V3) stages of soybean development. This period was found to be very similar to the CPWC previously defined by field studies of soybean–weed competition.

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Critical Period of Weed Control in Snap Bean on Organic Soils in South Florida

HortScience ◽

10.21273/hortsci12536-17 ◽

2018 ◽

Vol 53 (8) ◽

pp. 1129-1132

Author(s):

Dennis C. Odero ◽

Alan L. Wright

Keyword(s):

Weed Control ◽

Critical Period ◽

Yield Loss ◽

South Florida ◽

Maximum Length ◽

Organic Soils ◽

Open Flower ◽

Trifoliate Leaf ◽

Snap Bean ◽

Weed Interference

Field studies were conducted in 2011 and 2012 in Belle Glade, FL, to evaluate the critical period of weed control (CPWC) in snap bean grown on organic soils in the Everglades Agricultural Area (EAA) of South Florida. Treatments consisting of increasing duration of weed interference and weed-free period were imposed at weekly intervals from 0 to 7 weeks after emergence (WAE) of snap bean. The beginning and end of the CPWC based on 2.5%, 5%, and 10% snap bean acceptable yield loss (AYL) levels were determined by fitting log-logistic and Gompertz models to represent increasing duration of weed interference and weed-free period, respectively. Based on 2.5% yield loss, the CPWC was 7.2 weeks long, beginning 1.2 (cotyledon and unifoliate leaf) and ending 8.4 WAE (mid-pod set, 50% of pods reached maximum length). At 5% yield loss, the CPWC was 5.0 weeks, beginning 1.7 (first to second trifoliate leaf) and ending 6.7 WAE (mid-flower to early pod set, 50% of flowers open and one pod reached maximum length). At 10% yield loss, the CPWC was 3.0 weeks, beginning 2.2 (second trifoliate leaf) and ending 5.2 WAE (early flowering, one open flower). Based on these results, the beginning of CPWC was hastened, whereas the end was delayed at different yield loss levels showing that acceptable weed control in snap bean on organic soils in the EAA is required throughout much of the growing season to minimize yield loss.

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The Critical Period for Weed Control in Corn in Turkey

Weed Technology ◽

10.1614/wt-05-102.1 ◽

2006 ◽

Vol 20 (4) ◽

pp. 867-872 ◽

Cited By ~ 11

Author(s):

Dogan Isik ◽

Husrev Mennan ◽

Bekir Bukun ◽

Ahmet Oz ◽

Mathieu Ngouajio

Keyword(s):

Weed Control ◽

Critical Period ◽

Yield Loss ◽

Relative Yield ◽

Field Studies ◽

The Black Sea ◽

Yield Data ◽

Black Sea Region ◽

Weed Interference ◽

Loss Level

Field studies were conducted in 2001 and 2002 in the Black Sea Region of northern Turkey to determine the critical period for weed control (CPWC) in corn and the effects of weed interference on corn height. Treatments of increasing duration of weed interference and weed-free period were imposed at weekly intervals from 0 to 12 wk after crop emergence (WAE). The CPWC was determined with the use of 2.5, 5, and 10% acceptable yield loss levels by fitting logistic and Gompertz equations to relative yield data. With 5% yield loss level, the CPWC was 5 wk, starting at 0.2 WAE and ending at 5.2 WAE, which corresponded to the one- to five-leaf stage of corn. The CPWC increased to 8.9 wk, starting at 0 WAE and ending at 8.9 WAE, at the 2.5% yield loss level. At 10% yield loss level, the CPWC decreased to 1.7 wk, starting at 2.1 WAE and ending at 3.8 WAE.

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CHEMICAL WEED MANAGEMENT IN GRAIN SORGHUM AND SELECTIVITY OF ATRAZINE + S-METOLACHLOR TO DIFFERENT HYBRIDS

Revista Brasileira de Milho e Sorgo ◽

10.18512/1980-6477/rbms.v17n3p460-473 ◽

2018 ◽

Vol 17 (3) ◽

pp. 460

Author(s):

HUDSON KAGUEYAMA TAKANO ◽

AUGUSTO KALSING ◽

DAURI APARECIDO FADIN ◽

ROGERIO SILVA RUBIN ◽

RODRIGO NEVES ◽

...

Keyword(s):

Sorghum Bicolor ◽

Weed Control ◽

Weed Management ◽

Herbicide Tolerance ◽

Field Trials ◽

Grain Sorghum ◽

Efficacy And Safety ◽

Cereal Crop ◽

Weed Interference ◽

Herbicide Alternatives

ABSTRACT - Grain sorghum (Sorghum bicolor) is one cereal crop that faces huge problems with weed interference mostly because the lack of selective herbicides. This study aimed to assess the efficacy and safety of herbicide alternatives for weed control in grain sorghum as well as the selectivity of atrazine + s-metolachlor to different hybrids. Three field trials were designed as a randomized complete block with four replications. All experiments were conducted in Jardinópolis-SP and Mogi Mirim-SP during the 2015/16 growing season. Two trials included acetochlor, flumioxazin, fluroxypyr, mesotrione and s-metolachlor, applied in pre or post-emergence, in association or not with atrazine. A third trial was carried out with rates of the premix containing atrazine + s-metolachlor applied to the following hybrids: 1G100, 1G220, 1G230, 1G244, 1G282, 50A10, 50A40, 50A50 and 50A70. The pre‑emergence herbicides that exhibited satisfactory efficacy of weed control and selectivity to sorghum crop were flumioxazin, atrazine + mesotrione and atrazine + s-metolachlor. For post‑emergence, atrazine, atrazine + acetochlor, atrazine + s-metolachlor and atrazine + fluroxypyr were the best treatments for both efficacy and selectivity. The application of atrazine + s-metolachlor at the evaluated rates was considered selective to the nine hybrids assessed.Keywords: acetochlor, fluroxypyr, mesotrione, herbicide tolerance, weed control. MANEJO QUÍMICO DE PLANTAS DANINHAS EM SORGO GRANÍFERO E SELETIVIDADE DE ATRAZINE + S-METOLACHLOR PARA DIFERENTES HÍBRIDOS RESUMO – O sorgo granífero (Sorghum bicolor) é um dos cereais de verão que mais enfrenta problemas com plantas daninhas em razão da interferência destas espécies e carência de herbicidas para controlá-las. O objetivo deste estudo foi avaliar a eficácia e segurança de herbicidas alternativos no controle de plantas daninhas em sorgo granífero, assim como a seletividade de atrazine + s-metolachlor para diferentes híbridos. Três experimentos foram realizados em campo com delineamento de blocos ao acaso e quatro repetições, sendo conduzidos em Jardinópolis-SP e/ou Mogi Mirim-SP, ao longo da safra 2015/16. Em dois experimentos, acetochlor, flumioxazin, fluroxypyr, mesotrione e s-metolachlor foram avaliados em pré e/ou pós-emergência da cultura, em associação ou não (isolados) com atrazine. O terceiro experimento foi realizado com doses crescentes de atrazine + s-metolachlor e os híbridos de sorgo granífero 1G100, 1G220, 1G230, 1G244, 1G282, 50A10, 50A40, 50A50 e 50A70. Os tratamentos com controle satisfatório de plantas daninhas e seletividade à cultura, em pré-emergência, foram flumioxazin, atrazine + mesotrione e atrazine + s-metolachlor. Em pós-emergência, eles foram atrazine, atrazine + acetochlor, atrazine + s-metolachlor e atrazine + fluroxipyr. A aplicação de atrazine + s-metolachlor nas doses testadas foi seletiva para os nove híbridos avaliados.Palavras-chave: acetochlor, fluroxypyr, mesotrione, tolerância a herbicidas, controle de plantas daninhas. metolachlor at the evaluated rates was selective to the nine hybrids assessed.

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