An Index of Competition for Estimating Crop Loss Due to Weeds

Dew, D. A.

doi:10.4141/cjps72-159

Cited by 131 publications

(113 citation statements)

References 6 publications

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“…Estudos têm demonstrado que as perdas no rendimento de grãos, decorrentes da competição com ervas, variam em função da época de estabelecimento da cultura em relação às infestantes (Dew, 1972;Martin & Field, 1988;Knezevic et al, 1994). As ervas que emergem mais tarde do que as plantas da cultura geralmente exercem menor impacto no rendimento (Vandevender et al, 1997); já ervas que emergem mais cedo ganham vantagem sobre as espécies que emergem mais tarde, inclusive a cultura, e tornam-se melhor competidoras por recursos do ambiente.…”

Section: Abstract -This Study Was Conducted To Evaluate the Impact Ofunclassified

Período crítico para controle de Brachiaria plantaginea em função de épocas de semeadura da soja após dessecação da cobertura vegetal

et al. 2002

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Este trabalho objetivou avaliar o impacto da época de semeadura da soja após a dessecação da cobertura vegetal sobre o controle de papuã (Brachiaria plantaginea) e quantificar a influência da época de controle na produtividade da soja. O delineamento experimental utilizado foi o de parcelas subdivididas, em blocos casualizados, com quatro repetições. Os tratamentos constaram de épocas de semeadura da soja (1 e 10 dias após aplicação de dessecante - DAD), dispostas nas parcelas principais, e de épocas de controle de papuã (11, 17, 24, 31, 38 e 45 dias após a emergência da soja - DAE para a semeadura realizada em 1 DAD; e 8, 15, 22, 29, 36 e 42 DAE para a semeadura realizada aos 10 DAD), dispostas nas subparcelas. Para cada época de semeadura da soja foi mantida testemunha com controle químico de papuã durante todo o ciclo. O controle de papuã foi obtido mediante aplicação do herbicida clethodim a 120 g ha-1. Constatou-se que os níveis de controle de papuã, na pré-colheita da soja, variaram entre 90 e 99%, considerando-se todos os tratamentos. Houve reduções da estatura de planta de soja, rendimento biológico aparente e rendimento de grãos com o atraso na aplicação de controle ao papuã, especialmente para semeadura da soja realizada aos 10 DAD. Verificou-se que as perdas de rendimento de grãos, propiciadas pela convivência da planta daninha com a cultura, superaram o custo de controle aproximadamente aos 20 e 5 DAE da soja, quando as semeaduras foram efetuadas aos 1 e 10 DAD, respectivamente. O intervalo entre as aplicações de medidas de controle ao papuã é mais amplo quando a semeadura da soja é realizada mais próximo do momento de aplicação de dessecante do que quando sofre atraso.

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Section: Abstract -This Study Was Conducted To Evaluate the Impact Ofunclassified

Período crítico para controle de Brachiaria plantaginea em função de épocas de semeadura da soja após dessecação da cobertura vegetal

et al. 2002

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“…Flax is well known for being a poor competitor with weeds (Friesen and Shebeski 1960;Dew 1972). Bowden and Friesen (1967) reported average flax yield reductions of 24 and 50% from l2 and 48 wild oat plants m-2.…”

mentioning

confidence: 99%

Effects of Volunteer Wheat and Barley on the Growth and Yield of Flax

Friesen¹,

Morrison²,

Marshall³

et al. 1990

Can. J. Plant Sci.

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. Effects of volunteer wheat and barley on the growth and yield of flax. Can. J. Plant Sci. 70: 1115-1122. Fieid experiments were conducted in 1982 and 1983 to determine the effects of increasing densities (0-70 plants m '.; (Anonymous 1986(Anonymous , 1987b. Recent weed surveys confirm that volunteer wheat and barley commonly occur as weeds in flax fields (Thomas and Wise 1983.Flax is well known for being a poor competitor with weeds (Friesen and Shebeski 1960;Dew 1972). Bowden and Friesen (1967) reported average flax yield reductions of 24 and 50% from l2 and 48 wild oat plants m-2.respectively. Bell and Nalewaja (1968) reported similar results.Cereals bred for vigor and high yield are generally good competitors (Dew 1972

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“…Unlike the findings from many other studies (Leggett et al 1959;Banting 1962;Derksen et al 1994), wild oat populations were frequently lower in CF cropping systems than those from other cropping systems (see Table 5). Employing models developed by Dew (1972) and others (Cousens et al 1987;Dew and Keys 1976), some crop seed yield losses would be expected where difenzoquat or diclofop efficacy was inadequate. A final factor contributing to the enhanced crop seed yields from CF cropping systems was the poor performance of flax and red clover plowdown.…”

Section: Discussionmentioning

confidence: 99%

“…Applications were applied only when wild oat populations reached a level that would result in at least a 5-10% loss in crop yield. This was determined by models developed in previous studies (Cousens et al 1987;Dew 1972;Dew and Keys 1976). No herbicide was applied to the red clover in the year of plowdown.…”

Section: Specific Proceduresmentioning

confidence: 99%

Crop yields and wild oat control in northern Alberta cropping systems

Darwent¹,

Drabble²,

O’Donovan³

et al. 2003

Can. J. Plant Sci.

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A study was conducted on the Agriculture and Agri-Food Canada Research Farm, Beaverlodge, Alberta, to compare nine cropping systems in relation to productivity and wild oat (Avena fatua L.) control. The nine cropping systems consisted of three crop rotations and three levels of banded N fertilizer. Each cropping system had its own regime of tillage and weed control. One of the rotations consisted of mechanical fallow, along with canola (Brassica rapa L.), barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.), while the other two rotations consisted of the same annual crops, but with either flax (Linum usitatissimum L.) or red clover (Trifolium pratense L.) plowdown with partial fallow substituted for mechanical fallow. The three rates of banded N fertilizer were 0, 75 and 150% of recommended, based on soil tests and provincial recommendations. From 1991 to 1994, cropping systems with mechanical fallow and fall tillage after annual crops produced 24% higher total seed yields than cropping systems with no fall tillage after annual crops and either continuous annual crops or red clover plowdown. Increasing the rate of banded N fertilizer from 0 to 75% of recommended increased total crop seed yields but a further increase from 75 to 150% had no significant effect. Although cropping systems with mechanical fallow had an advantage over other cropping systems, the effect of crop sequencing and yearly weather conditions on total crop seed yields was greater than the effect of cropping systems. Wild oat populations varied greatly with year, but the ease of management was greater in cropping systems with the mechanical fallow than in other cropping systems. Wild oat density increased when diclofop or difenzoquat performed inadequately or when poor red clover establishment allowed populations to increase. Reductions in wild oat populations appeared to be largely due to the consistent effectiveness of sethoxydim. , alors que les deux autres consistaient en une rotation des mêmes cultures annuelles plus la culture de lin (Linum usitatissimum L.) ou celle de trèfle rouge (Trifolium pratense L.) comme engrais vert, puis jachère partielle à la place de la jachère mécanique. L'engrais azoté a été épandu à un taux correspondant à 0, à 75 ou à 150 % du taux recommandé après analyse du sol et selon les recommandations provinciales. De 1991 à 1994, les régimes avec jachère mécanique et travail du sol à l'automne après récolte des cultures annuelles ont présenté un rendement grainier de 24 % supérieur à celui des systèmes sans retournement du sol à l'automne et culture continue ou utilisation de trèfle rouge comme engrais vert. Quand la fertilisation passe de 0 à 75 % du taux recommandé, on assiste à une hausse du rendement grainier, mais doubler la quantité d'engrais azoté de 75 à 150 % n'exerce aucun effet sensible sur la récolte. Bien que les systèmes agricoles avec jachère mécanique présentent un avantage sur les autres régimes, la succession des cultures et les conditions météorologiques durant l'année agissent plus sur l...

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An Index of Competition for Estimating Crop Loss Due to Weeds

Cited by 131 publications

References 6 publications

Período crítico para controle de Brachiaria plantaginea em função de épocas de semeadura da soja após dessecação da cobertura vegetal

Período crítico para controle de Brachiaria plantaginea em função de épocas de semeadura da soja após dessecação da cobertura vegetal

Effects of Volunteer Wheat and Barley on the Growth and Yield of Flax

Crop yields and wild oat control in northern Alberta cropping systems

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