Determination of the critical period of weed control in corn using a thermal basis

Field studies were conducted over 3 years in southeast Buenos Aires, Argentina, to determine the critical period of weed control in maize (Zea mays L.). The treatments consisted of two different periods of weed interference, a critical weed-free period, and a critical time of weed removal. The Gompertz and logistic equations were fitted to relative yields representing the critical weed-free and the critical time of weed removal, respectively. Accumulated thermal units were used to describe each period of weed-free or weed removal. The critical weed-free period and the critical time of weed removal ranged from 222 to 416 and 128 to 261 accumulated thermal units respectively, to prevent yield losses of 2.5%. Weed biomass proved to be inverse to the crop yield for all the years studied. When weeds competed with the crop from emergence, a large increase in weed biomass was achieved 10 days after crop emergence. However, few weed seedlings emerged and prospered after the 5-6 leaf maize stage (10-20 days after emergence).

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The Critical Period of Weed Control in Grain Corn (Zea mays)

Weed Science ◽

10.1017/s0043174500051882 ◽

1992 ◽

Vol 40 (3) ◽

pp. 441-447 ◽

Cited By ~ 236

Author(s):

Michael R. Hall ◽

Clarence J. Swanton ◽

Glenn W. Anderson

Keyword(s):

Zea Mays ◽

Leaf Area ◽

Weed Control ◽

Critical Period ◽

Field Studies ◽

Southern Ontario ◽

Leaf Stage ◽

Individual Leaf ◽

Logistic Equations ◽

Weed Interference

Field studies were conducted in southern Ontario to determine the critical period of weed control in grain corn and the influence of weed interference on corn leaf area. The Gompertz and logistic equations were fitted to data representing increasing durations of weed control and weed interference, respectively. The beginning of the critical period varied from the 3- to 14-leaf stages of corn development However, the end of the critical period was less variable and ended on average at the 14-leaf stage. Weed interference reduced corn leaf area by reducing the expanded leaf area of each individual leaf and accelerating senescence of lower leaves. In addition, weed interference up to the 14-leaf stage of corn development impeded leaf expansion and emergence in 1989.

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The Critical Period of Weed Control in White Bean (Phaseolus vulgaris)

Weed Science ◽

10.1017/s0043174500076037 ◽

1993 ◽

Vol 41 (2) ◽

pp. 180-184 ◽

Cited By ~ 38

Author(s):

Brian L. Woolley ◽

Thomas E. Michaels ◽

Michael R. Hall ◽

Clarence J. Swanton

Keyword(s):

Phaseolus Vulgaris ◽

Weed Control ◽

Critical Period ◽

Yield Loss ◽

Field Studies ◽

Weed Biomass ◽

Weed Interference ◽

Stages Of Growth ◽

White Bean ◽

Pod Number

Field studies were conducted in 1986 and 1987 to determine the critical period for weed control in white bean grown in Ontario. The treatments consisted of either allowing weeds to infest the crop for increasing durations after planting or maintaining plots weed free for increasing durations after planting. The beginning of the critical period was defined as the crop stage by which weed interference reduced yields by 3%. Similarly, the end of the critical period was defined as the crop stage to which the crop had to be weed free to prevent a 3% yield loss. The critical period of weed control occurred between the second-trifoliolate and first-flower stages of growth for all cultivars and years, with the exception of the cultivar ‘OAC Seaforth’ in 1986. The average number of pods per plant for both cultivars was reduced by increasing durations of weed interference after planting in both years. However, pod number of the cultivar OAC Seaforth was reduced at a greater rate in 1986 than ‘Ex Rico 23’. The beginning of the critical period corresponded with the beginning of a rapid increase in total weed biomass.

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The Critical Period of Weed Control in Soybean [Glycine max(L.) Merr.]

Weed Science ◽

10.1017/s0043174500076050 ◽

1993 ◽

Vol 41 (2) ◽

pp. 194-200 ◽

Cited By ~ 133

Author(s):

Rene C. Van Acker ◽

Clarence J. Swanton ◽

Stephan F. Weise

Keyword(s):

Weed Control ◽

Critical Period ◽

Growth Stage ◽

Yield Loss ◽

Critical Time ◽

Field Studies ◽

Glycine Max L ◽

Postemergence Herbicides ◽

Residual Herbicide ◽

Weed Removal

Field studies were conducted at three locations over 2 yr in southern Ontario to determine the critical period of weed control in soybean. This period generally consisted of two discrete periods, a critical weed-free period and a critical time of weed removal. The critical weed-free period was relatively short in duration and consistent across locations and years. A period of weed control lasting up to the fourth node growth stage (V4), approximately 30 days after emergence (DAE), was adequate to prevent a yield loss of more than 2.5%. The critical time of weed removal was variable across locations and years and ranged, for example, from the second node growth stage (V2) to the beginning pod growth stage (R3), approximately 9 to 38 DAE, at a 2.5% yield loss level. A phenologically based period of most rapid yield loss due to weed interference occurred from beginning bloom stage (R1) to beginning seed stage (R5). The short and consistent critical weed-free period indicates the duration of residual herbicide control necessary in soybean and supports use of nonresidual, postemergence herbicides and mechanical weed control.

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Influence of a Rye Cover Crop on the Critical Period for Weed Control in Cotton

Weed Science ◽

10.1614/ws-d-14-00075.1 ◽

2015 ◽

Vol 63 (1) ◽

pp. 346-352 ◽

Cited By ~ 22

Author(s):

Nicholas E. Korres ◽

Jason K. Norsworthy

Keyword(s):

Weed Control ◽

Cover Crops ◽

Cover Crop ◽

Critical Period ◽

Yield Loss ◽

Growing Season ◽

Weed Biomass ◽

Weed Density ◽

Presence And Absence ◽

Weed Removal

Cover crops are becoming increasingly common in cotton as a result of glyphosate-resistant Palmer amaranth; hence, a field experiment was conducted in 2009 and 2010 in Marianna, AR, with a rye cover crop used to determine its effects on the critical period for weed control in cotton. Throughout most of the growing season, weed biomass in the presence of a rye cover crop was lesser than that in the absence of a rye cover crop. In 2009, in weeks 2 through 7 after planting, weed biomass was reduced at least twofold in the presence of a rye cover compared with the absence of rye. In 2009, in both presence and absence of a rye cover crop, weed removal needed to begin before weed biomass was 150 g m−2, or approximately 4 wk after planting, to prevent yield loss > 5%. Weed density was less in 2010 than in 2009, so weed removal was not required until 7 wk after planting, at which point weed biomass values were 175 and 385 g m−2in the presence and absence of a cover crop, respectively.

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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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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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Determining the critical period for broadleaf weed control in high-yielding cotton using mungbean as a mimic weed

Weed Technology ◽

10.1017/wet.2020.38 ◽

2020 ◽

Vol 34 (5) ◽

pp. 689-698

Author(s):

Graham W. Charles ◽

Brian M. Sindel ◽

Annette L. Cowie ◽

Oliver G. G. Knox

Keyword(s):

Weed Control ◽

Critical Period ◽

Yield Loss ◽

Critical Time ◽

Field Studies ◽

Cotton Field ◽

Control Input ◽

Degree Days ◽

Weed Density ◽

The Relationship

AbstractResearch using the critical period for weed control (CPWC) has shown that high-yielding cotton crops are very sensitive to competition from grasses and large broadleaf weeds, but the CPWC has not been defined for smaller broadleaf weeds in Australian cotton. Field studies were conducted over five seasons from 2003 to 2015 to determine the CPWC for smaller broadleaf weeds, using mungbean as a mimic weed. Mungbean was planted at densities of 1, 3, 6, 15, 30, and 60 plants m−2 with or after cotton emergence and added and removed at approximately 0, 150, 300, 450, 600, 750, and 900 degree days of crop growth (GDD). Mungbean competed strongly with cotton, with season-long interference; 60 mungbean plants m−2 resulted in an 84% reduction in cotton yield. A dynamic CPWC function was developed for densities of 1 to 60 mungbean plants m−2 using extended Gompertz and exponential curves including weed density as a covariate. Using a 1% yield-loss threshold, the CPWC defined by these curves extended for the full growing season of the crop at all weed densities. The minimum yield loss from a single weed control input was 35% at the highest weed density of 60 mungbean plants m−2. The relationship for the critical time of weed removal was further improved by substituting weed biomass for weed density in the relationship.

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Critical Period for Weed Control in Leek (Allium porrum L.)

HortScience ◽

10.21273/hortsci.42.1.106 ◽

2007 ◽

Vol 42 (1) ◽

pp. 106-109 ◽

Cited By ~ 14

Author(s):

Nihat Tursun ◽

Bekir Bükün ◽

Sinan Can Karacan ◽

Mathieu Ngouajio ◽

Hüsrev Mennan

Keyword(s):

Weed Control ◽

Critical Period ◽

Relative Yield ◽

Field Studies ◽

Allium Porrum ◽

Yield Data ◽

Fresh Biomass ◽

Weed Interference ◽

Weed Infestation ◽

Loss Level

Field studies were conducted in Mersin, Turkey, in 2002 and 2003 to determine the critical period for weed control in leek and to investigate the effects of weed interference on weed biomass. The critical period for weed control in leek based on a 5% acceptable yield loss level was calculated by fitting logistic and Gompertz equations to relative yield data. Total fresh biomass of weeds increased as the duration of weed infestation increased. The beginning of the critical period for weed control was 7 days after transplanting in 2002 and 13 days after transplanting in 2003. The end of the critical period for weed control was 85 days after transplanting in 2002 and 60 days after transplanting in 2003. Results of this study suggest that leek should be kept weed free between 7 days after transplanting and 85 days after transplanting to avoid yield losses in excess of 5%.

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Weed Management in Glyphosate- and Glufosinate-Resistant Sugar Beet

Weed Technology ◽

10.1614/wt-07-114.1 ◽

2009 ◽

Vol 23 (3) ◽

pp. 416-424 ◽

Cited By ~ 12

Author(s):

Nathan J. Kemp ◽

Erin C. Taylor ◽

Karen A. Renner

Keyword(s):

Sugar Beet ◽

Weed Control ◽

Critical Period ◽

Field Experiments ◽

Yield Loss ◽

Root Yield ◽

Beet Root ◽

Weed Interference ◽

Sugar Beet Root ◽

Weed Removal

Field experiments were conducted to determine the critical period of weed interference in glyphosate- and glufosinate-resistant sugar beet, and to determine if PRE herbicides increased weed control or sugar beet root yield when glufosinate, glyphosate, or conventional POST herbicides were applied. Glyphosate- and glufosinate-resistant sugar beet root yields were reduced by up to 66 and 67%, respectively, when weeds remained all season in the weedy control treatment compared with yields when weed removal occurred as soon as the weeds were 2.5 cm tall, approximately 2 to 3 wk after planting (WAP). A critical period of weed interference did not occur in this research. The critical time of weed removal was approximately 8 WAP in 1998 and beyond 11 WAP in 1999. Weeds averaged 20 cm in height at 8 WAP and weed densities were greater in 1998 compared with 1999. The critical weed-free period for glyphosate- and glufosinate-resistant sugar beet was 4.5 to 5 WAP in 1998. In 1999, the critical weed-free period at the Michigan Sugar location was 1.5 WAP in glyphosate-resistant sugar beet, and 6.5 WAP in glufosinate-resistant sugar beet for the Michigan Sugar site. Glyphosate or glufosinate POST provided better weed control and resulted in greater sugar beet root yield compared with conventional POST herbicides when data were combined over PRE herbicide treatments. PRE herbicides improved the control of common lambsquarters andAmaranthusspecies in some of the site-years when data were combined over POST treatments, but sugar beet yield did not increase. Our research suggests that PRE herbicides will not be necessary in glyphosate- or glufosinate-resistant sugar beet. To avoid sugar beet yield loss, multiple POST applications of glyphosate or glufosinate will be needed until 6 to 9 WAP to prohibit yield loss from weeds emerging after the last POST application.

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Safety and efficacy of linuron with or without an adjuvant or S-metolachlor for POST control of Palmer amaranth (Amaranthus palmeri) in sweetpotato

Weed Technology ◽

10.1017/wet.2021.27 ◽

2021 ◽

pp. 1-18

Author(s):

Levi D. Moore ◽

Katherine M. Jennings ◽

David W. Monks ◽

Ramon G. Leon ◽

David L. Jordan ◽

...

Keyword(s):

Nonionic Surfactant ◽

Weed Control ◽

Critical Period ◽

Total Yield ◽

Field Studies ◽

Palmer Amaranth ◽

Amaranthus Palmeri ◽

Foliar Injury ◽

Protoporphyrinogen Oxidase ◽

Safety And Efficacy

Abstract Field studies were conducted to evaluate linuron for POST control of Palmer amaranth in sweetpotato to minimize reliance on protoporphyrinogen oxidase (PPO)-inhibiting herbicides. Treatments were arranged in a two by four factorial where the first factor consisted of two rates of linuron (420 and 700 g ai ha−1), and the second factor consisted of linuron applied alone or in combinations of linuron plus a nonionic surfactant (NIS) (0.5% v/v), linuron plus S-metolachlor (800 g ai ha−1), or linuron plus NIS plus S-metolachlor. In addition, S-metolachlor alone and nontreated weedy and weed-free checks were included for comparison. Treatments were applied to ‘Covington’ sweetpotato 8 d after transplanting (DAP). S-metolachlor alone provided poor Palmer amaranth control because emergence had occurred at applications. All treatments that included linuron resulted in at least 98 and 91% Palmer amaranth control 1 and 2 wk after treatment (WAT), respectively. Including NIS with linuron did not increase Palmer amaranth control compared to linuron alone, but increased sweetpotato injury and subsequently decreased total sweetpotato yield by 25%. Including S-metolachlor with linuron resulted in the greatest Palmer amaranth control 4 WAT, but increased crop foliar injury to 36% 1 WAT compared to 17% foliar injury from linuron alone. Marketable and total sweetpotato yield was similar between linuron alone and linuron plus S-metolachlor or S-metolachlor plus NIS treatments, though all treatments resulted in at least 39% less total yield than the weed-free check resulting from herbicide injury and/or Palmer amaranth competition. Because of the excellent POST Palmer amaranth control from linuron 1 WAT, a system including linuron applied 7 DAP followed by S-metolachlor applied 14 DAP could help to extend residual Palmer amaranth control further into the critical period of weed control while minimizing sweetpotato injury.

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