Spatial weed distribution and economic thresholds for weed control

Thornton, Philip K.; Fawcett, R.H.; Dent, J. B.; Perkins, Tim

doi:10.1016/0261-2194(90)90003-p

Cited by 118 publications

(96 citation statements)

References 4 publications

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“…Most bioeconomic weed models pay little or no attention to the spatial distribution of weeds (Doyle, 1991;. However, the use of information on the spatial variability of weed populations can have a substantial effect on the calculation of threshold values and hence on the decision of whether or not to spray (Thornton et al, 1990). For example, Thornton et al (1990) provided experimental evidence that the economic threshold value increases when the heterogeneity of weeds is considered.…”

Section: Management Strategies Which Take Account Of the Spatial Hetementioning

confidence: 99%

“…However, the use of information on the spatial variability of weed populations can have a substantial effect on the calculation of threshold values and hence on the decision of whether or not to spray (Thornton et al, 1990). For example, Thornton et al (1990) provided experimental evidence that the economic threshold value increases when the heterogeneity of weeds is considered. These researchers photographed a field of winter wheat, digitized the images, and then estimated the density of weeds.…”

Section: Management Strategies Which Take Account Of the Spatial Hetementioning

confidence: 99%

“…The threshold concept can be summarized as follows : as the density of the weed population increases, the gain in crop yield from chemical control becomes greater than the costs of the herbicide and its application (Thornton et al, 1990). Most bioeconomic weed models pay little or no attention to the spatial distribution of weeds (Doyle, 1991;.…”

Section: Management Strategies Which Take Account Of the Spatial Hetementioning

confidence: 99%

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Extent and Implications of Weed Spatial Variability in Arable Crop Fields

Garibay¹,

Richner²,

Stamp³

et al. 2001

Plant Production Science

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: The integration of technologies and principles to assess, manage, and evaluate spatial and temporal variability has enabled the site-specific application of variable rates of agrochemicals. It is referred to as precision management. This article concerns with the potential of precision management for weed control. Weeds are heterogeneously distributed and show different levels of spatial aggregation. A better understanding of weed patchiness is necessary for precision weed management. Studies reviewed in this article showed that significant reduction in the amount of herbicide can be achieved when the spatial variability of weeds is taken into account. It is often difficult, however, to obtain information on the spatial distribution of weeds with accuracy because it depends on monitoring techniques, scales of observation, and statistical methods applied. We conclude that the precision application of herbicides is one approach to managing weeds and it will be possible to achieve a drastic reduction in herbicide applications by using a combination of several different types of weed control strategies. Not only farmers with large fields but also those with small fields should have better access to information on spatial variability to make decisions for weed control.

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Section: Management Strategies Which Take Account Of the Spatial Hetementioning

confidence: 99%

Section: Management Strategies Which Take Account Of the Spatial Hetementioning

confidence: 99%

Section: Management Strategies Which Take Account Of the Spatial Hetementioning

confidence: 99%

See 1 more Smart Citation

Extent and Implications of Weed Spatial Variability in Arable Crop Fields

Garibay¹,

Richner²,

Stamp³

et al. 2001

Plant Production Science

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“…In the United Kingdom, crop yield loss estimates based on random and aggregated weed distributions were compared (Brain and Cousens 1990;Thornton et al 1990). It was concluded that under farm conditions, models that assume a random distribution would overestimate crop yield loss predictions.…”

Section: Discussionmentioning

confidence: 99%

Field evaluation of regression equations to estimate crop yield losses due to weeds

O’Donovan¹,

Blackshaw²,

Harker³

et al. 2005

Can. J. Plant Sci.

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. 2005. Field evaluation of regression equations to estimate crop yield losses due to weeds. Can. J. Plant Sci. 85: 955-962. Various regression equations based on weed density alone, or relative time of weed and crop emergence or crop density in addition to weed density have been developed in western Canada to estimate the effects of wild oat (Avena fatua L.) and volunteer cereals on yield loss of field crops, and to advise farmers on the economics of weed control with herbicides. In , 1998, several of these equations were evaluated in 9 barley (Hordeum vulgare L.), 9 wheat (Triticum aestivum L.) and 11 canola (Brassica napus L.) fields in Alberta. Wild oat was the dominant weed in the barley and wheat fields, and wild oat or volunteer cereals in the canola fields. In barley and wheat, more complex equations based on both weed density and either crop density or relative time of weed and crop emergence were more reliable in estimating yield losses due to wild oat than those based on weed density alone. In canola, an equation based on volunteer barley and canola density provided the most reliable estimates. Under the assumed crop prices and herbicide costs, these equations also resulted in the best estimates of whether or not a herbicide application resulted in a net profit or loss. Herbicide application was rarely economical in barley, but usually economical in wheat and canola reflecting the different market value of the crops. The implementation of the weed economic threshold concept is likely to be more feasible in low-value crops such as feed barley than in higher-value crops such as canola. Dans l'ouest du Canada, on se sert d'équations de régression pour estimer l'incidence de la folle avoine (Avena fatua L.) et de la repousse spontanée des céréales sur le rendement des cultures d'après la densité de peuplement des adventices, la levée des mauvaises herbes et des cultures ou la densité de peuplement des adventices et de la culture, l'objectif étant de conseiller les agriculteurs sur le désherbage chimique. Les auteurs ont évalué plusieurs de ces équations dans 9 champs d'orge (Hordeum vulgare L.), 9 de blé (Triticum aestivum L.) et 11 de canola (Brassica napus L.) de l'Alberta en 1997, 1998 et 1999. La folle avoine était la principale adventice dans les champs d'orge et de blé alors que ceux de canola étaient surtout envahis par la folle avoine et les repousses spontanées de céréales. Dans les champs de blé et d'orge, les équations plus complexes, reposant à la fois sur la densité de peuplement des mauvaises herbes et sur celle de la culture ou sur la levée relative de l'adventice et de l'espèce cultivée sont plus fiables que les équations se fondant uniquement sur la densité de peuplement de la mauvaise herbe pour estimer les pertes de rendement attribuables à la folle avoine. Dans les champs de canola, c'est l'équation reposant sur la densité des repousses spontanées d'orge et sur la densité du canola qui donne les estimations les plus sûres. Compte tenu du prix hypothétique de la culture et des herbicide...

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“…This clustering of weed populations has been well described by a nég-ative binomial distribution (Marshall 1988). Crop yield loss estimâtes based on random and négative binomial weed distributions were compared in studies conducted in the United Kingdom (Brain and Cousens 1990; Thornton et al 1990). The authors concluded that under farm conditions, crop yield loss estimâtes will be overestimated by models that assume a random weed distribution.…”

Section: Realistic Sampling Methodologymentioning

confidence: 99%

Weed economic thresholds : Useful agronomic tool or pipe dream?

O’Donovan

2005

phyto

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L'intérêt pour des approches de lutte contre les mauvaises herbes plus ration nelles et objectives s'est considérablement accru au Canada et ailleurs. Les questions de coût/bénéfices, les préoccupations environnementales et le développement de la résistance aux herbicides ont semé le doute sur la pertinence et la possibilité de poursuivre l'utilisation préventive des herbicides. Le concept de seuil d'intervention économique pour les mauvaises herbes et le concept plus large de lutte intégrée présentent un potentiel important comme outils agronomiques pratiques dans les systèmes de production canadiens. Un grand nombre d'expériences ont été menées afin de déterminer l'impact des mauvaises herbes sur le rendement des cultures, mais les modèles développés à partir de ces études ont été peu mis en pratique. Les contraintes à la mise en pratique de ces concepts comprennent l'absence de protocoles d'échantillonnage réalistes afin de déterminer l'impact des mauvaises herbes sur les cultures sur de vastes étendues, ainsi qu'un manque de renseignements sur les implications à long terme de la production de graines par les mauvaises herbes non contrôlées. Les malherbologistes qui mènent des expériences sur l'interférence causée par les mauvaises herbes devraient mieux définir leurs objectifs et devraient fournir des directives sur la façon dont leurs résultats peuvent être utilisés à la ferme. L'accent devrait être placé sur l'effet des cultures sur les mauvaises herbes plutôt que sur l'effet des mauvaises herbes sur les cultures. Une meilleure coordination des activités de recherche des malherbologistes s'impose. La mise en place de protocoles standards pour les études à long terme entre les sites et les années augmenterait la pertinence et la précision des modèles d'interférence, et pourrait conduire au développement de systèmes d'aide à la décision conviviaux et adaptés spécifiquement à la prise de décisions rationnelles de lutte contre les mauvaises herbes dans les systèmes canadiens de production des cultures. Le développement de tels systèmes sera essentiel à la mise en place de seuils d'intervention et de méthodes de lutte intégrée contre les mauvaises herbes.Interest in more rational and objective approaches to weed management has increased considerably in Canada and elsewhere. Cost/benefit issues, environmental concerns, and the development of weed resistance to herbicides have cast doubt on the rationality and sustainability of prophylactic herbicide use. The concept of an economic threshold for weeds and the broader concept of integrated weed management have considerable potential as practical agronomic tools in Canadian crop production Systems. A large number of experiments have been conducted to determine the impact of weeds on crop yield, but the models developed from these studies have been put to little practical use. Constraints to the practical implementation of these concepts include a lack of realistic sampling procedures to assess the impact of weeds on crops over large areas, and a lack of information ...

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Spatial weed distribution and economic thresholds for weed control

Cited by 118 publications

References 4 publications

Extent and Implications of Weed Spatial Variability in Arable Crop Fields

Extent and Implications of Weed Spatial Variability in Arable Crop Fields

Field evaluation of regression equations to estimate crop yield losses due to weeds

Weed economic thresholds : Useful agronomic tool or pipe dream?

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