The introduction of glyphosate resistance into Australian cotton systems will have an effect on conventional weed management practices, the weed species present and the risk of glyphosate resistance evolving in weed species. Therefore, it is important that the effects of these management practices, particularly a potential reduction in Integrated Weed Management (IWM) practices, be examined to determine their impact on weed population dynamics and resistance selection. The study began in 2003 with a survey of 40 growers in four major cotton growing regions in Australia to gain an understanding of how adoption of glyphosate resistance had influenced the weed spectrum, weed management practices and herbicide use after three years of glyphosate-resistant cotton being available. The 10 most common weeds reported on cotton fields were the same in glyphosate-resistant and conventional fields. In this survey, herbicide use patterns were altered by the adoption of glyphosate-resistant cotton with up to six times more glyphosate being applied and with 21% fewer growers applying pre-emergence herbicides in glyphosate-resistant cotton fields. Other weed control practices, such as the use of post-emergence herbicides, inter-row cultivation and hand hoeing, were only reduced marginally. A systems experiment was conducted to determine differences in the population dynamics of Echinochloa crus-galli (barnyardgrass) and Urochloa panicoides (liverseed grass) under a range of weed management regimes in a glyphosate-resistant cotton system. These treatments ranged from a full IWM system to a system based soley on the use of glyphosate. The experiment investigated the effect of the treatments on the soil seed bank, weed germination patterns and weed numbers in the field. All applied treatments resulted in commercially acceptable control of the two grass weeds. However, the treatments containing soil-applied residual herbicides proved to be more effective over the period of the experiment. The treatment with a reduced residual herbicide program supplemented with glyphosate had a level of control similar to the full IWM treatments with less input, providing a more economical option. The effectiveness of these treatments in the long-term was examined in a simulation model to determine the likelihood of glyphosate resistance evolving using barnyardgrass and liverseed grass as model weeds. Seed production and above-ground biomass of barnyardgrass and liverseed grass in competition with cotton were measured. In all experiments, seed production and biomass plant⁻¹ decreased as weed density increased while seed production and biomass m⁻¹ tended to increase. Seed production m⁻¹ reached 40,000 and 60,000 for barnyardgrass and liverseed grass, respectively. In 2004-05, weeds were also planted 6 weeks and 12 weeks after the cotton was planted. Biomass and seed production of the two weeds planted 6 weeks after cotton were significantly reduced with seed production declining to 12,000 and 2,500 seeds m⁻¹ row for barnyardgrass and liverseed grass, respectively. Weeds planted 12 weeks after cotton planting failed to emerge. This experiment highlighted the importance of early season weed control and effective management of weeds that are able to produce high seed numbers. A glyphosate dose-mortality experiment was conducted in the field to determine levels of control of barnyardgrass and liverseed grass. Glyphosate provided effective control of both species with over 85% control when the rate applied was greater than 690 g ae ha⁻¹. Dose-mortality curves for both species were obtained for use in the glyphosate resistance model. Data from the experimental work were combined to develop a glyphosate resistance model. Outputs from this model suggest that if glyphosate were used as the only form of weed control, resistance in weeds is likely to eventuate after 12 to 17 years, depending on the characteristics of the weed species, initial resistance gene frequencies and any associated fitness penalties. If glyphosate was used in conjunction with one other weed control method, resistance was delayed but not prevented. The simulations suggested that when a combination of weed control options was employed in addition to glyphosate, resistance would not evolve over the 30-year period of the simulation. These simulations underline the importance of an integrated strategy in weed management to prevent glyphosate resistance evolving from the use of glyphosate-resistant cotton. Current management conditions of growing glyphosate-resistant (Roundup Ready &reg) cotton should therefore prevent glyphosate resistance evolution. / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2006.

Bibliography: leaves 147-163. / ix, 164 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The aim of this thesis is to confirm the resistance status of three purported resistant weed species by herbicide screening of outdoor pot grown plants. Field experiments are set up to investigate changes in dormancy and seedbank life of the resistant populations over a three year period. After determining the herbicide resistance spectrum of the resistant biotypes, genetic crosses between resistant and susceptible plants are performed to follow the mode of inheritance of acetolactate synthase (ALS) resistance. "In vitro" ALS enzyme assays in the presence of various herbicides are carried out to reveal a modified ALS enzyme as the main mechanism of resistance in all cases. A molecular investigation of the ALS gene is performed to identify mutations responsible for endowing a resistant enzyme. / Thesis (Ph.D.)--University of Adelaide, Dept. of Crop Protection, 1996

The introduction of glyphosate resistance into Australian cotton systems will have an effect on conventional weed management practices, the weed species present and the risk of glyphosate resistance evolving in weed species. Therefore, it is important that the effects of these management practices, particularly a potential reduction in Integrated Weed Management (IWM) practices, be examined to determine their impact on weed population dynamics and resistance selection. The study began in 2003 with a survey of 40 growers in four major cotton growing regions in Australia to gain an understanding of how adoption of glyphosate resistance had influenced the weed spectrum, weed management practices and herbicide use after three years of glyphosate-resistant cotton being available. The 10 most common weeds reported on cotton fields were the same in glyphosate-resistant and conventional fields. In this survey, herbicide use patterns were altered by the adoption of glyphosate-resistant cotton with up to six times more glyphosate being applied and with 21% fewer growers applying pre-emergence herbicides in glyphosate-resistant cotton fields. Other weed control practices, such as the use of post-emergence herbicides, inter-row cultivation and hand hoeing, were only reduced marginally. A systems experiment was conducted to determine differences in the population dynamics of Echinochloa crus-galli (barnyardgrass) and Urochloa panicoides (liverseed grass) under a range of weed management regimes in a glyphosate-resistant cotton system. These treatments ranged from a full IWM system to a system based soley on the use of glyphosate. The experiment investigated the effect of the treatments on the soil seed bank, weed germination patterns and weed numbers in the field. All applied treatments resulted in commercially acceptable control of the two grass weeds. However, the treatments containing soil-applied residual herbicides proved to be more effective over the period of the experiment. The treatment with a reduced residual herbicide program supplemented with glyphosate had a level of control similar to the full IWM treatments with less input, providing a more economical option. The effectiveness of these treatments in the long-term was examined in a simulation model to determine the likelihood of glyphosate resistance evolving using barnyardgrass and liverseed grass as model weeds. Seed production and above-ground biomass of barnyardgrass and liverseed grass in competition with cotton were measured. In all experiments, seed production and biomass plant⁻¹ decreased as weed density increased while seed production and biomass m⁻¹ tended to increase. Seed production m⁻¹ reached 40,000 and 60,000 for barnyardgrass and liverseed grass, respectively. In 2004-05, weeds were also planted 6 weeks and 12 weeks after the cotton was planted. Biomass and seed production of the two weeds planted 6 weeks after cotton were significantly reduced with seed production declining to 12,000 and 2,500 seeds m⁻¹ row for barnyardgrass and liverseed grass, respectively. Weeds planted 12 weeks after cotton planting failed to emerge. This experiment highlighted the importance of early season weed control and effective management of weeds that are able to produce high seed numbers. A glyphosate dose-mortality experiment was conducted in the field to determine levels of control of barnyardgrass and liverseed grass. Glyphosate provided effective control of both species with over 85% control when the rate applied was greater than 690 g ae ha⁻¹. Dose-mortality curves for both species were obtained for use in the glyphosate resistance model. Data from the experimental work were combined to develop a glyphosate resistance model. Outputs from this model suggest that if glyphosate were used as the only form of weed control, resistance in weeds is likely to eventuate after 12 to 17 years, depending on the characteristics of the weed species, initial resistance gene frequencies and any associated fitness penalties. If glyphosate was used in conjunction with one other weed control method, resistance was delayed but not prevented. The simulations suggested that when a combination of weed control options was employed in addition to glyphosate, resistance would not evolve over the 30-year period of the simulation. These simulations underline the importance of an integrated strategy in weed management to prevent glyphosate resistance evolving from the use of glyphosate-resistant cotton. Current management conditions of growing glyphosate-resistant (Roundup Ready &reg) cotton should therefore prevent glyphosate resistance evolution. / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2006.

The introduction of glyphosate resistance into Australian cotton systems will have an effect on conventional weed management practices, the weed species present and the risk of glyphosate resistance evolving in weed species. Therefore, it is important that the effects of these management practices, particularly a potential reduction in Integrated Weed Management (IWM) practices, be examined to determine their impact on weed population dynamics and resistance selection. The study began in 2003 with a survey of 40 growers in four major cotton growing regions in Australia to gain an understanding of how adoption of glyphosate resistance had influenced the weed spectrum, weed management practices and herbicide use after three years of glyphosate-resistant cotton being available. The 10 most common weeds reported on cotton fields were the same in glyphosate-resistant and conventional fields. In this survey, herbicide use patterns were altered by the adoption of glyphosate-resistant cotton with up to six times more glyphosate being applied and with 21% fewer growers applying pre-emergence herbicides in glyphosate-resistant cotton fields. Other weed control practices, such as the use of post-emergence herbicides, inter-row cultivation and hand hoeing, were only reduced marginally. A systems experiment was conducted to determine differences in the population dynamics of Echinochloa crus-galli (barnyardgrass) and Urochloa panicoides (liverseed grass) under a range of weed management regimes in a glyphosate-resistant cotton system. These treatments ranged from a full IWM system to a system based soley on the use of glyphosate. The experiment investigated the effect of the treatments on the soil seed bank, weed germination patterns and weed numbers in the field. All applied treatments resulted in commercially acceptable control of the two grass weeds. However, the treatments containing soil-applied residual herbicides proved to be more effective over the period of the experiment. The treatment with a reduced residual herbicide program supplemented with glyphosate had a level of control similar to the full IWM treatments with less input, providing a more economical option. The effectiveness of these treatments in the long-term was examined in a simulation model to determine the likelihood of glyphosate resistance evolving using barnyardgrass and liverseed grass as model weeds. Seed production and above-ground biomass of barnyardgrass and liverseed grass in competition with cotton were measured. In all experiments, seed production and biomass plant⁻¹ decreased as weed density increased while seed production and biomass m⁻¹ tended to increase. Seed production m⁻¹ reached 40,000 and 60,000 for barnyardgrass and liverseed grass, respectively. In 2004-05, weeds were also planted 6 weeks and 12 weeks after the cotton was planted. Biomass and seed production of the two weeds planted 6 weeks after cotton were significantly reduced with seed production declining to 12,000 and 2,500 seeds m⁻¹ row for barnyardgrass and liverseed grass, respectively. Weeds planted 12 weeks after cotton planting failed to emerge. This experiment highlighted the importance of early season weed control and effective management of weeds that are able to produce high seed numbers. A glyphosate dose-mortality experiment was conducted in the field to determine levels of control of barnyardgrass and liverseed grass. Glyphosate provided effective control of both species with over 85% control when the rate applied was greater than 690 g ae ha⁻¹. Dose-mortality curves for both species were obtained for use in the glyphosate resistance model. Data from the experimental work were combined to develop a glyphosate resistance model. Outputs from this model suggest that if glyphosate were used as the only form of weed control, resistance in weeds is likely to eventuate after 12 to 17 years, depending on the characteristics of the weed species, initial resistance gene frequencies and any associated fitness penalties. If glyphosate was used in conjunction with one other weed control method, resistance was delayed but not prevented. The simulations suggested that when a combination of weed control options was employed in addition to glyphosate, resistance would not evolve over the 30-year period of the simulation. These simulations underline the importance of an integrated strategy in weed management to prevent glyphosate resistance evolving from the use of glyphosate-resistant cotton. Current management conditions of growing glyphosate-resistant (Roundup Ready &reg) cotton should therefore prevent glyphosate resistance evolution. / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2006.

Thesis (M.S.)--Missouri State University, 2008. / "May 2008." Includes bibliographical references (leaves 39-42). Also available online.

Made available in DSpace on 2015-03-03T11:52:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-12-12Bitstream added on 2015-03-03T12:06:48Z : No. of bitstreams: 1 000813767.pdf: 1901576 bytes, checksum: 6b5082108a5848dc7f1470e545454df7 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste trabalho foi caracterizar quatro populações de Conyza spp. bioquimicamente e morfofisiologicamente. Os experimentos foram realizados em casa de vegetação com quatro populações (P1, P3 e P4 – Conyza sumatrensis; P2 – Conyza bonariensis) que foram coletados em diferentes municípios do estado de São Paulo. Os tratamentos foram constituídos da aplicação de doses do herbicida glyphosate: 45, 90, 180, 360, 720, 1440, 2880, 5760 e 11520 g e.a. ha-1; e uma testemunha sem aplicação. No momento da aplicação as plantas apresentavam de 5 a 6 folhas totalmente expandidas. Foi realizado um estudo preliminar e mais três estudos, com os mesmos tratamentos, mas com avaliações distintas. O estudo preliminar foi composto de um experimento com a população 4, onde foram avaliados aos 28 dias após os tratamentos (DAT) a altura das plantas, porcentagem de controle, massa fresca de parte aérea, e quantificação dos seguintes compostos por cromatografia líquida de alta eficiência e espectrometria de massas (LCMS/ MS): glyphosate, ácido aminometilfosfônico (AMPA), ácido chiquímico, ácido desidrochiquímico, fenilalanina, tirosina, triptofano, e ácido salicílico. No primeiro estudo foram realizadas as curvas de dose resposta para as quatro populações testadas. No estudo seguinte, aos 14 DAT foi realizada a coleta de todas as folhas de cada planta (repetição) para quantificação dos mesmos compostos já descritos no estudo preliminar, além do ácido indolacético (IAA) e ácido abscísico (ABA) por LC-MS/MS. O último estudo teve como objetivo avaliar o crescimento, florescimento e produção de sementes, por meio de avaliações de altura, número de brotações laterais, número de capítulos abertos e número ... / The objective of this research was to characterize four Conyza spp. populations biochemically and morphophisiologically. The experiments were carried out in a greenhouse with four populations (P 1, 3 and 4 - Conyza sumatrensis; P 2 - Conyza bonariensis). Seeds were collected in different municipalities of the Sao Paulo state. The treatments consisted of the glyphosate application in different doses: 45, 90, 180, 360, 720, 1440, 2880, 5760 and 11520 g ae ha-1 and one untreated control. The herbicide glyphosate was applied to plants with 5-6 expanded leaves. Were performed a preliminary study and three others studies, with the same treatments but with different evaluations. The preliminary study consisted of an experiment with population 4, which was evaluated at 28 days after treatment (DAT) the plant height, percentage of control, fresh weight of plants, and quantitation of glyphosate, aminomethylphosphonic acid (AMPA), shikimic acid, dehydroshikimic acid, phenylalanine, tyrosine, tryptophan, and salicylic acid by LC-MS/MS. In the first study, the dose response curves were performed. In the following study, at 14 DAT, all the leaves of each plant were ...

Field and greenhouse research was conducted in 2009 and 2010 on herbicide applications enabled by the integration of Optimum GAT crop traits providing for resistance to glyphosate and certain ALS-inhibiting herbicides. The herbicide concepts were evaluated for control of several winter and summer annual weed species, as well as the effect of the resulting weed control on grain yield of Optimum GAT soybean. The combination of chlorimuron + rimsulfuron did not provide sufficient efficacy on the winter annual grass species little barley and annual bluegrass. Factors contributing the sub-lethal activity include: 1) a relatively low inherent sensitivity of the species to these herbicides, 2) a significant reduction in herbicide efficacy with increases in weed plant height, and 3) a lack of herbicide enhancement with more aggressive foliar adjuvants. The tank-mixture of glyphosate with chlorimuron + rimsulfuron was frequently necessary to achieve a maximum herbicide activity above 90% on annual bluegrass and little barley. Optimum GAT herbicide treatments including chlorimuron + rimsulfuron + flumioxazin in field experiments provided the greatest control of horseweed and common waterhemp in glyphosate-susceptible and -resistant populations. The addition of chlorimuron + rimsulfuron to glyphosate and 2,4-D improved horseweed control above glyphosate and 2,4-D applied alone even as weed height increased with applications made closer to soybean planting. However, removal of competitive vegetation with herbicide combinations including chlorimuron + rimsulfuron selected for emergence of ALS-resistant common waterhemp. Inclusion of flumioxazin with chlorimuron + rimsulfuron was beneficial for control of common waterhemp when applied 7 days before planting. However, chlorimuron + rimsulfuron + flumioxazin provided only 80% control of common waterhemp in a glyphosate-resistant population which demonstrates opportunity for improvement in herbicide concepts enabled by Optimum GAT. Grain yield of Optimum GAT soybean was greatest for herbicide treatments which provided effective weed management throughout the growing season which were the herbicide treatments applied the closest to soybean planting (7 days before planting). Optimum GAT herbicide concepts for corn include chlorimuron + thifensulfruon + tribenuron, chlorimuron + rimsulfuron, and rimsulfuron + tribenuron + mesotrione. These herbicides provided similar to slightly increased control of annual morningglory (Ipomoea spp.) in comparison to glyphosate alone. The addition of atrazine increased the consistency of control of annual morningglory for any herbicide treatment with additional residual activity at 28 days after treatment. Optimum GAT enabled herbicide concepts can improve control of some problematic weed species, including some glyphosate-resistant weed populations, compared to current herbicide tactics that rely primarily on glyphosate for weed control in commercial glyphosate-resistant soybean and corn. However, the integration of postemergence soybean herbicides beyond the ALS chemistry is necessary to provide a broader spectrum of weed control when considering the challenges of managing both glyphosate- and ALS-resistant weed species that are becoming more frequent in commercial fields.

Made available in DSpace on 2015-09-17T15:26:26Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-05-25. Added 1 bitstream(s) on 2015-09-17T15:45:39Z : No. of bitstreams: 1 000847006.pdf: 350277 bytes, checksum: db6c508303c5e5af00e03576f372683c (MD5) / Se aplicados no estágio e na dose correta, os herbicidas são altamente tóxicos para as plantas. As populações de plantas daninhas suscetíveis a um determinado herbicida são totalmente controladas quando a dose recomendada é corretamente aplicada. No entanto, há uma evolução contínua na sobrevivência e crescimento das plantas em resposta a baixas doses dos herbicidas como resultado da presença de características que podem causar um baixo nível de resistência a estes produtos. Estudos de seleção recorrente podem revelar se a variação fenotípica em resposta a uma dose baixa do herbicida é hereditária e pode conduzir à resistência ao herbicida. Estudos de seleção recorrente de plantas alógamas de Lolium rigidum sobreviventes baixas doses de herbicidas mostraram rápida evolução da resistência a herbicidas em apenas três gerações por intensificação progressiva de características de resistência a herbicidas inicialmente pouco relevantes. Em um estudo de campo, populações autógamas de Avena fatua foram submetidas a um processo de seleção recorrente resultante da aplicação de baixas doses do herbicida diclofop-methyl (inibidor da ACCase) ou o glyphosate (inibidor da EPSPS). As aplicações sucessivas de diclofop-methyl induziram o desenvolvimento de progênies distintas da população original em termos de resistência a este herbicida, com o aumento de duas vezes na LD50. As progênies selecionadas pelo uso de diclofop-methyl também mostraram-se mais resistentes a herbicidas inibidores da ALS indicando sugerindo a ocorrência de resistência cruzada. As aplicações sucessivas de glyphosate não induziram a formação de progênies mais resistentes. A capacidade da A. fatua para responder à pressão de seleção imposta por baixas doses de herbicidas é limitada e muito mais baixa ... / Herbicides when applied at the correct stage and dose are highly toxic to plants. Herbicide-susceptible weed populations are completely controlled at the recommended herbicide label dose. However, there is continuous variation in plant survival and growth in response to herbicide low doses (below-label) because specific plant traits can confer some low level resistance. Recurrent (directional) selection studies can reveal whether such a phenotypic variation in response to a herbicide low dose is heritable and can lead to herbicide resistance. Recurrent selection studies with allogamous cross-pollinated Lolium rigidum plants surviving at a low herbicide dose showed rapid evolution of herbicide resistance in three generations by progressive enrichment of minor herbicide resistance traits. In a common experimental garden study, we have subjected to low-dose recurrent selection a susceptible population of autogamous self-pollinated Avena fatua with the ACCase-inhibiting herbicide diclofop-methyl or the EPSPS-inhibiting glyphosate. Significant differences in response to selection between the selected progenies and parents were evident in the lines selected by low-dose diclofop-methyl, whereas glyphosate selection did not results in significant shifts. A two-fold diclofop resistance was quantified by comparison of estimated LD50 values and a significant increase in survival to ALS-inhibiting herbicides suggests cross-resistance. Importantly, the capacity of A. fatua to respond to low-dose herbicide selection is marginal and much lower than in L. rigidum. The dynamics of selection and the factors driving the evolution of resistance to herbicides in plants are discussed with particular emphasis on the implications of low-dose herbicide use weed management of autogamous self-pollinated vs allogamous cross ...

Orientador: Edivaldo Domingues Velini / Banca: Fernando Tadeu de Carvalho / Banca: Fernando Storniolo Adegas / Banca: Eduardo Negrisoli / Banca: Pedro Jaccob Christoffoleti / Resumo: O objetivo deste trabalho foi caracterizar quatro populações de Conyza spp. bioquimicamente e morfofisiologicamente. Os experimentos foram realizados em casa de vegetação com quatro populações (P1, P3 e P4 - Conyza sumatrensis; P2 - Conyza bonariensis) que foram coletados em diferentes municípios do estado de São Paulo. Os tratamentos foram constituídos da aplicação de doses do herbicida glyphosate: 45, 90, 180, 360, 720, 1440, 2880, 5760 e 11520 g e.a. ha-1; e uma testemunha sem aplicação. No momento da aplicação as plantas apresentavam de 5 a 6 folhas totalmente expandidas. Foi realizado um estudo preliminar e mais três estudos, com os mesmos tratamentos, mas com avaliações distintas. O estudo preliminar foi composto de um experimento com a população 4, onde foram avaliados aos 28 dias após os tratamentos (DAT) a altura das plantas, porcentagem de controle, massa fresca de parte aérea, e quantificação dos seguintes compostos por cromatografia líquida de alta eficiência e espectrometria de massas (LCMS/ MS): glyphosate, ácido aminometilfosfônico (AMPA), ácido chiquímico, ácido desidrochiquímico, fenilalanina, tirosina, triptofano, e ácido salicílico. No primeiro estudo foram realizadas as curvas de dose resposta para as quatro populações testadas. No estudo seguinte, aos 14 DAT foi realizada a coleta de todas as folhas de cada planta (repetição) para quantificação dos mesmos compostos já descritos no estudo preliminar, além do ácido indolacético (IAA) e ácido abscísico (ABA) por LC-MS/MS. O último estudo teve como objetivo avaliar o crescimento, florescimento e produção de sementes, por meio de avaliações de altura, número de brotações laterais, número de capítulos abertos e número ... / Abstract: The objective of this research was to characterize four Conyza spp. populations biochemically and morphophisiologically. The experiments were carried out in a greenhouse with four populations (P 1, 3 and 4 - Conyza sumatrensis; P 2 - Conyza bonariensis). Seeds were collected in different municipalities of the Sao Paulo state. The treatments consisted of the glyphosate application in different doses: 45, 90, 180, 360, 720, 1440, 2880, 5760 and 11520 g ae ha-1 and one untreated control. The herbicide glyphosate was applied to plants with 5-6 expanded leaves. Were performed a preliminary study and three others studies, with the same treatments but with different evaluations. The preliminary study consisted of an experiment with population 4, which was evaluated at 28 days after treatment (DAT) the plant height, percentage of control, fresh weight of plants, and quantitation of glyphosate, aminomethylphosphonic acid (AMPA), shikimic acid, dehydroshikimic acid, phenylalanine, tyrosine, tryptophan, and salicylic acid by LC-MS/MS. In the first study, the dose response curves were performed. In the following study, at 14 DAT, all the leaves of each plant were ... / Doutor

MSc. (Geography) / Growing concerns with regards to the environmental and economic impacts related to the application of herbicides to control the spread and abundance of weeds in agricultural crops have created a need for the development of novel agricultural management systems that are less dependent on herbicide usage and tillage. Such concerns have given rise to the need for the variable spatial treatment of croplands aimed at the minimization of requirements for the application of herbicides and the subsequent minimization of excess materials released into the surrounding environment. Remote sensing provides an opportunity for the fast and cost-effective delineation of weed patches in croplands over large areas where traditional scouting techniques would be impractical. The differences in spectral reflectance from different plants at certain wavelengths due to species specific variations in biochemical and physical characteristics is what lays the basis for the distinction of vegetation species within remotely sensed images and ultimately the potential detection of weed-species in croplands. This study investigates the potential spectral characterisation of maize and commonly occurring weed-species by (1) making use of reflectance spectra collected at leaf-level to identify statistically significant differences in reflectance between individual species throughout the visible (VIS), Near-Infrared (NIR) and Shortwave-Infrared (SWIR) regions of the electromagnetic spectrum, determining the potential of the Red-Edge Position (REP) and slope for this particular application and testing the accuracy at which reflectance spectra may be classified according to vegetation species based on spectral reflectance at specific wavebands and REP as input predictor variables, (2) testing the potential effect of mixed spectral responses and soil-background interference through the analysis of reflectance spectra collected at canopy-level, and (3) determining the potential effect of the spectral generalisation associated with multispectral reflectance through the analysis of spectral responses resampled to the spectral band designations of representative high spatial resolution multispectral sensors. The results showed that maize may be spectrally distinguished from all of the weed-species included in the analysis based on leaf-level hyperspectral reflectance throughout the Visible-to-Near-Infrared (V-NIR) and SWIR-regions of the electromagnetic spectrum, however, the unique characterisation of weed-species is not possible for all species and where it is possible, it is highly wavelength-specific and would require high spectral resolution hyperspectral data. The wavelengths most suitable for the spectral characterisation of maize-crops and weed species in the study area were identified as: 432.1nm, 528.2nm, 700.7nm, 719.4nm, 1335.1nm, 1508.1nm, 2075.8nm, 2164.5nm and 2342.2nm. The output predictor model was able to classify reflectance spectra associated with maize crops and weeds in the study area at an overall accuracy of 89.7 per cent and it was shown that the inclusion of the REP as predictor variable did not improve the overall accuracy of the classification, however, may be used to improve the classification accuracies of certain species...