Volunteer RR® corn management in roundup ready® soybean-corn succession system

The present study evaluated the effects of cover crops (Pennisetum glaucum, Crotalaria spectabilis and Urochloa ruziziensis) associated with the application of herbicides {glyphosate; (glyphosate + haloxyfop-R); (glyphosate + fluazifop-p-butyl); (glyphosate + imazethapyr) and (glyphosate + imazaquin)} in soybean desiccation management for volunteer RR® corn control. The experiment was conducted under field conditions at Sinop-MT, during the 2013/2014 crop season, in a randomized complete blocks design with factorial scheme and four replications. The following parameter were evaluated: dry matter of cover crops and ground coverage rate, control of volunteer RR® corn present at the time of desiccation, dry matter, height and intoxication level on soybean plants caused by herbicides at 7, 14 and 28 days after emergence (DAE), control of volunteer RR® corn derived from emergence fluxes subsequent to desiccation management and soybean yield. The joint application of (glyphosate + haloxyfop-R) provided the best level of volunteer RR® corn control present at the time of desiccation. Satisfactory control (80%) of volunteer corn was obtained with the application of (glyphosate + imazethapyr). This treatment displayed an additional residual effect of imazethapyr, which efficiently controled volunteer RR® corn derived from fluxes subsequent to desiccation management, especially in treatments performed under U. ruziziensis straw. None of the herbicides used in desiccation management caused any significant effect on dry matter, height and phytotoxicity of soybean plants at 7, 14 and 28 DAE nor on grain yield.

SELECTION OF HERBICIDES TARGETING THE USE IN CROP SYSTEMS CULTIVATED WITH SHOWY CROTALARIA

ABSTRACT The increase in the area planted with Crotalaria spectabilishas occurred by several factors, highlighting the potential to reduce the nematodes, nitrogen fixation and the high production of biomass. By becoming a species sown as a crop, it is necessary to control the weeds that coexist with showy crotalaria. This change in the use of this crop creates the possibility of this specie becoming a weed. The aim of this study was to assess the potential use of herbicides applied in preemergence and postemergence of C.spectabilisfor different purposes (control of volunteer and selectivity plants). Three experiments were installed in a greenhouse (two with herbicides applied in preemergence - in soils with distinct textural categories; and one experiment with herbicides applied in postemergence). The results of the experiments with herbicides applied in preemergence showed that: amicarbazone, atrazine, diuron, metribuzin, prometryn, fomesafen and sulfentrazone showed effectiveness for control of C.spectabilis in clayey soil. Besides these, flumioxazin and isoxaflutole also showed potential to be used in the control of showy crotalaria in soils with loam texture. In relation to the postemergence herbicides, atrazine, diuron, prometryn, flumioxazin, fomesafen, lactofen, saflufenacil, amonio-glufosinate and glyphosate can be used aiming the chemical control of C.spectabilis. Herbicides chlorimuron-ethyl, diclosulan, imazethapyr, pyrithiobac-sodium, trifloxysulfuron-sodium, clomazone, pendimethalin, S-metolachlor and trifluralin applied in preemergence, and imazethapyr, pyrithiobac-sodium, flumiclorac, bentazon and clethodim applied in postemergence caused low levels of injury to C.spectabilis plants, making necessary the development of new searches to ensure the selectivity of these products.

CHEMICAL CONTROL OF WHITE CLOVER IN SOYBEAN CROPS

ABSTRACTWhite clover is tolerant to many herbicides, making difficult a chemical control of this species during soybean crop establishments. The objective of this research was to select herbicides applied postemergence to control white clover in soybean and know the effects of this control on soybean yield. Seven herbicides were assessed, applied postemergence, with or without sequential application of glyphosate, and two control treatments (no control and total control of white clover). Glyphosate (with two sequential applications), fomesafen (with a sequential application of glyphosate), chlorimuron-ethyl and lactofen have shown a satisfactory control of white clover (above 80%). The lower control efficiency has resulted in lower production of soybeans.

Physiological and Genetic Bases of the Circadian Clock in Plants and Their Relationship with Herbicides Efficacy

In order to adapt to daily environmental changes, especially in relation to light availability, many organisms, such as plants, developed a vital mechanism that controls time-dependent biological events: the circadian clock. The circadian clock is responsible for predicting the changes that occur in the period of approximately 24 hours, preparing the plants for the following phases of the cycle. Some of these adaptations can influence the response of weeds to the herbicide application. Thus, the objectives of this review are to describe the physiological and genetic mechanisms of the circadian clock in plants, as well as to demonstrate the relationship of this phenomenon with the effectiveness of herbicides for weed control. Relationships are described between the circadian clock and the time of application of herbicides, leaf angle and herbicide interception, as well as photosynthetic activity in response to the circadian clock and herbicide efficiency. Further, it is discussed the role of phytochrome B (phyB) in the sensitivity of plants to glyphosate herbicide. The greater understanding of the circadian clock in plants is essential to achieve greater efficiency of herbicides and hence greater control of weeds and higher crop yields.

Increased immunoglobulin production in silver catfish (Rhamdia quelen) exposed to agrichemicals

Fish vaccination has been increasingly exploited as a tool to control pathogen infection. The production of immunoglobulin following vaccination might be affected by several factors such as management procedures, water temperature, and the presence of xenobiotics. In the present study, we aimed to investigate the kinetics of immunoglobulin production in silver catfish (Rhamdia quelen) inoculated with inactivated Aeromonas hydrophila and kept at two different water temperatures (17.4±0.4° or 21.3±0.3°C). The effect of a second antigen inoculation and exposure of fish to sublethal concentrations of the herbicides atrazine and glyphosate at 10% of the lethal concentration (LC50-96h) on specific serum antibodies were also investigated. Antibodies to A. hydrophila were detected as early as 7 days post-inoculation and increased steadily up to 35 days. The kinetics of antibody production were similar in fish kept at 17.4±0.4° and 21.3±0.3°C, and reinoculation of antigen at 21 days after priming failed to increase specific antibody levels. Intriguingly, we found that, in fish exposed to atrazine and glyphosate, the secretion of specific antibodies was higher than in non-exposed inoculated fish. These findings are important for the design of vaccines and vaccination strategies in Neotropical fish species. However, because atrazine and glyphosate are widespread contaminants of soil and water, their immune-stimulating effect could be harmful, in that fish living in herbicide-contaminated water might have increased concentrations of nonspecific antibodies that could mediate tissue injury.

Detection of adventitious presence of genetically modified seeds in lots of non transgenic soybean

The difficulty on identifying, lack of segregation systems and absence of suitable standards for coexistence of non trangenic and transgenic soybean are contributing for contaminations that occur during productive system. The objective of this study was to evaluate the efficiency of two methods for detecting mixtures of seeds genetically modified (GM) into samples of non-GM soybean, in a way that seed lots can be assessed within the standards established by seed legislation. Two sizes of soybean samples (200 and 400 seeds), cv. BRSMG 810C (non-GM) and BRSMG 850GRR (GM), were assessed with four contamination levels (addition of GM seeds, for obtaining 0.0%, 0.5%, 1.0%, and 1.5% contamination), and two detection methods: immunoassay of lateral flux (ILF) and bioassay (pre-imbibition into 0.6% herbicide solution; 25 ºC; 16 h). The bioassay is efficient in detecting presence of GM seeds in seed samples of non-GM soybean, even for contamination lower than 1.0%, provided that seeds have high physiological quality. The ILF was positive, detecting the presence of target protein in contaminated samples, indicating test effectiveness. There was significant correlation between the two detection methods (r = 0.82; p < 0.0001). Sample size did not influence efficiency of the two methods in detecting presence of GM seeds.

Lutte intégrée au roseau commun : prévention, confinement et éradication

Les plantes envahissantes menacent la biodiversité ainsi que les activités humaines. Afin de les maîtriser, la pulvérisation d'herbicides est une méthode fréquemment employée en Amérique du Nord. Cette approche ne fait pas toujours consensus et est même parfois interdite ou restreinte, ce qui justifie le recours à d'autres options. Les alternatives peuvent toutefois s'avérer rares, comporter d'importantes limitations ou sont peu documentées. Cette étude vise à tester l’efficacité de méthodes permettant de maîtriser et de prévenir les invasions de roseau commun (Phragmites australis), l'une des plantes envahissantes les plus problématiques sur le continent nord-américain, tout en limitant au minimum l'utilisation d'herbicides. Le potentiel de quatre méthodes de lutte aux petites populations de roseau bien établies a d'abord été évalué : l’excavation avec enfouissement sur place, le bâchage, l’excavation avec enfouissement sur place combinée au bâchage, et la fauche répétée. Les résultats ont montré que l'excavation avec enfouissement sur place, avec ou sans bâchage, a entraîné une élimination presque totale des populations visées, ce qui est comparable ou supérieur à l'effet généralement obtenu avec la pulvérisation d'herbicide. Le bâchage avec des toiles opaques, maintenues pendant un an, a pour sa part entraîné une maîtrise partielle du roseau, suggérant qu'une application prolongée serait nécessaire pour l'éradication de la plante. La fauche répétée, exécutée à raison de cinq fauches par été pendant deux ans, a fourni une efficacité mitigée. Les résultats suggèrent néanmoins que la fauche pendant plusieurs années contribue à affaiblir la plante, ce qui pourrait aider à son confinement. Une méthode additionnelle a été expérimentée afin de traiter les tiges éparses de roseau tout en limitant les risques d'effets hors cibles, soit le badigeonnage manuel d’herbicide. Suite à ces tests, les résultats ont montré une diminution importante de la densité des tiges, ce qui suggère que la méthode est efficace afin d'éliminer les repousses après un traitement initial, et pourrait également être employée sur de jeunes populations clairsemées. L'effet d'un ensemencement préventif de plantes herbacées sur l'établissement de semis de roseau a également été étudié, suite à des traitements sur de vastes parcelles de sol nu. Les résultats suggèrent que la méthode est efficace afin de limiter la propagation du roseau par semences et qu'un suivi périodique suite à l'intervention serait suffisant afin de maintenir l'effet préventif.

Methods for short-term control of Imperata grass in Peruvian Amazon

The traditional control of Imperata brasiliensis grasslands used by farmers in the Peruvian Amazon is to burn the grass. The objective of this study was to compare different methods of short-term control. Biological, mechanical, chemical and traditional methods of control were compared. Herbicide spraying and manual weeding have shown to be very effective in reducing above- and below-ground biomass growth in the first 45 days after slashing the grass, with effects persisting in the longer term, but both are expensive methods. Shading seems to be less effective in the short-term, whereas it influences the Imperata growth in the longer term. After one year shading, glyphosate application and weeding significantly reduced aboveground biomass by 94, 67 and 53%; and belowground biomass by 76, 65 and 58%, respectively, compared to control. We also found a significant decrease of Imperata rhizomes in soil during time under shading. Burning has proved to have no significant effect on Imperata growth. The use of shade trees in a kind of agroforestry system could be a suitable method for small farmers to control Imperata grasslands.

Análisis del antagonismo entre el discurso del gobierno de Álvaro Uribe Vélez y el discurso de las comunidades indígenas de la Sierra Nevada de Santa Marta, en torno a las fumigaciones con glifosato (2002 - 2006)

El discurso del gobierno de Álvaro Uribe Vélez en su primer periodo presidencial, y el discurso de las comunidades indígenas de la Sierra Nevada de Santa Marta en torno a las fumigaciones con glifosato resultan en una relación antagónica, la cual produce una deslegitimación de la identidad cultural necesaria para la supervivencia de las comunidades indígenas. El análisis de los elementos de dicho antagonismo permite entender cómo se articula el discurso reivindicativo de las comunidades indígenas y cómo se fortifica la lucha reivindicativa por la legitimación de la identidad cultural. El discurso reivindicativo unifica las demandas generadas por dichas comunidades en torno a las fumigaciones con glifosato, mientras la lucha reivindicativa por la legitimación pretende resolver estas demandas y sentar las bases de un modelo de accionar político regido a partir de la aplicación de la palabra y el pensamiento tradicional de los pueblos indígenas.

Análisis del papel de la política de erradicación forzosa con glifosato en relación a las dinámicas del conflicto armado en Nariño años 2000 - 2006

La concentración de la política de fumigacion con glifosato en regiones como el Putumayo y Caquetá, trajo consigo un enorme desplazamiento de los cultivos de coca hacia Nariño (efecto globo). Motivados por ejercer un control estratégico de estos nuevos recursos, los grupos armados ilegales reflejaron un creciente interés por copar el territorio, fomentando una cruenta lucha que condujo a una degradación de las dinámicas del conflicto armado en la región.

Lo ambiental y lo social de la aspersión en Colombia. ¿Política ambiental o estrategia antinarcóticos?

En este artículo se revisan y analizan algunos aspectos del Programa de Erradicación de Cultivos Ilícitos con Glifosato (PECIG) y su Plan de Manejo Ambiental, con el ánimo de demostrar que no consideran de manera adecuada los componentes ambiental y social. Desde la perspectiva de las políticas públicas se demuestra que se ajustan más a una estrategia militar-antinarcóticos que social y medioambiental, contrario al querer transmitido en la definición del instrumento, que habla de la compensación, prevención y mitigación de impactos, la protección de los recursos naturales, del medio ambiente y de la salud de la ciudadanía ubicada en las zonas de influencia directa. Para ello, se hace un recuento de cómo está definido el Programa y los organismos que lo componen; después se explica el Plan de Manejo Ambiental y el análisis de su implementación, posteriormente se muestran los resultados obtenidos de esta verificación para, finalmente, formular las respectivas conclusiones.-----This paper reviews and analyzes issues of the Illicit Crop Eradication Program with Glyphosate (ICEPG) and its Environmental Management Plan, with the aim to demonstrate that the environmental and social components have not been properly considered. From the public policy viewpoint, they are shown to fit more into a military antinarcotics strategy rather than a social and environmental strategy, as opposed to the aims contained in the instrument definition, which talks about impact compensation, prevention, and mitigation; and protection of natural resources, environment, and population’s health within the direct influence areas. For this purpose, an initial review of the Program definition and component organizations is provided; the Environmental Management Plan is explained, its implementation is analyzed; the results from this verification are shown; and, finally, the respective conclusions are formulated.

Desenvolupament de metodologia analítica per a la determinació de glifosat i adjuvants

El glifosat és un herbicida no selectiu àmpliament utilitzat en cultius agrícoles i zones no agrícoles que requereixen un control de la vegetació. Tot i la baixa toxicitat del glifosat en si mateix, la seva aplicació es realitza emprant formulacions comercials que contenen substàncies auxiliars que milloren l'eficàcia de l'herbicida, però modifiquen la toxicitat del producte final.Aquest treball s'ha centrat en la determinació de components de formulacions comercials d'herbicides i el seu comportament en el sòl. La primera part del treball s'ha dedicat al desenvolupament de mètodes d'anàlisi per a la determinació de glifosat i el seu principal metabòlit, AMPA, en matrius aquoses i sòls. A continuació s'ha desenvolupat un mètode d'anàlisi per les substàncies auxiliars addicionades freqüentment en les formulacions comercials, tensioactius no iònics. Finalment s'ha estudiat la mobilitat de l'herbicida en sòls de la zona mediterrània, incidint en els processos d'adsorció i degradació. També s'ha comparat el comportament de diversos herbicides comercials que contenen glifosat.

Desenvolupament de mètodes de preconcentració emprant membranes líquides suportades i extracció en fase sòlida per a la determinació de l'herbicida glifosat i el seu metabòlit AMPA en aigües naturals

El glifosat, N-(fosfonometil) glicina, és un dels herbicides més utilitzats arreu del món a causa de la seva baixa toxicitat i al seu ampli espectre d'aplicació. A conseqüència del gran ús que se'n fa, és necessari monitoritzar aquest compost i el seu principal metabòlit, l'àcid aminometilfosfònic (AMPA), en el medi ambient. S'han descrit diversos mètodes instrumentals basats en cromatografia de gasos (GC) i de líquids (HPLC), sent aquesta darrera l'opció més favorable a causa del caràcter polar dels anàlits. Per assolir nivells de concentració baixos cal, però, la preconcentració dels anàlits. En aquest treball s'estudien diferents alternatives amb aquest objectiu. S'ha avaluat la tècnica de membrana líquida suportada (SLM) on la membrana consisteix en una dissolució orgànica, que conté un transportador (en el nostre cas, un bescanviador d'anions comercial, Aliquat 336), que impregna un suport polimèric microporós que se situa entre dues solucions aquoses: la de càrrega, que conté els anàlits inicialment, i la receptora, on es retenen els anàlits després del seu transport a través de la membrana. Les condicions d'extracció més adequades s'obtenen treballant en medi bàsic amb NaOH on els anàlits estan en forma aniònica i les majors recuperacions s'obtenen amb HCl 0,1 M o NaCl 0,5 M, la qual cosa indica que l'ió clorur és la força impulsora del transport. Un cop dissenyat el sistema, es duen a terme experiments de preconcentració amb dues geometries diferents: un sistema de membrana laminar (LSLM) on recircula la fase receptora i un sistema de fibra buida (HFSLM). Els millors resultats s'obtenen amb el mòdul de fibra buida, amb factors de concentració de 25 i 3 per a glifosat i AMPA, respectivament, fent recircular durant 24 hores 100 ml de solució de càrrega i 4 ml de solució receptora. També s'aplica una tècnica més selectiva, la cromatografia d'afinitat amb ió metàl·lic immobilitzat (IMAC), basada en la interacció entre els anàlits i un metall immobilitzat en una resina a través d'un grup funcional d'aquesta. En aquest estudi s'immobilitza pal·ladi al grup funcional 8-hidroxiquinoleïna de la resina amb matriu acrílica Spheron Oxine 1000 i s'avalua per a l'extracció i preconcentració de glifosat i AMPA. Per a ambdós anàlits l'adsorció és del 100 % i les recuperacions són superiors al 80 % i al 60 % per a glifosat i AMPA, respectivament, utilitzant HCl 0,1 M + NaCl 1 M com a eluent. Aquests resultats es comparen amb els obtinguts amb dues resines més, també carregades amb pal·ladi: Iontosorb Oxin 100, que té el mateix grup funcional però matriu de cel·lulosa, i Spheron Thiol 1000, on el grup funcional és un tiol i la matriu també és acrílica. Per al glifosat els resultats són similars amb totes les resines, però per a l'AMPA la resina Spheron Thiol és la única que proporciona recuperacions superiors al 93 %. Finalment, una altra opció estudiada és l'acoblament de dues columnes de cromatografia líquida (LC-LC). En l'estudi l'objectiu és millorar el mètode existent per a glifosat i AMPA en aigües naturals on el LOD era de 0,25 ug/l. El mètode consisteix en la derivatització precolumna amb el reactiu fluorescent FMOC i l'anàlisi amb l'acoblament LC-LC-fluorescència. Variant lleugerament les condicions de derivatització s'aconsegueix quantificar 0,1 ug/l de glifosat i AMPA. Es fortifiquen aigües naturals amb 0,1, 1 i 10 ug/l dels anàlits per validar el mètode. S'obtenen recuperacions d'entre el 85 % i el 100 %, amb desviacions estàndard relatives inferiors al 8 %. Aplicant una tècnica de preconcentració prèvia a la derivatització i anàlisi utilitzant una resina de bescanvi aniònic, Amberlite IRA-900, es millora la sensibilitat del mètode i s'assoleix un LOD per al glifosat de 0,02 ug/l.

Environmental and human health impacts of growing genetically modified herbicide-tolerant sugar beet: a life-cycle assessment

There is ongoing debate concerning the possible environmental and human health impacts of growing genetically modified (GM) crops. Here, we report the results of a life-cycle assessment (LCA) comparing the environmental and human health impacts of conventional sugar beet growing regimes in the UK and Germany with those that might be expected if GM herbicide-tolerant (to glyphosate) sugar beet is commercialized. The results presented for a number of environmental and human health impact categories suggest that growing the GM herbicide-tolerant crop would be less harmful to the environment and human health than growing the conventional crop, largely due to lower emissions from herbicide manufacture, transport and field operations. Emissions contributing to negative environmental impacts, such as global warming, ozone depletion, ecotoxicity of water and acidification and nutrification of soil and water, were much lower for the herbicide-tolerant crop than for the conventional crop. Emissions contributing to summer smog, toxic particulate matter and carcinogenicity, which have negative human health impacts, were also substantially lower for the herbicide-tolerant crop. The environmental and human health impacts of growing GM crops need to be assessed on a case-by-case basis using a holistic approach. LCA is a valuable technique for helping to undertake such assessments.

Studies on weed infestation and tea growth under various weed management methods in a young Tea (Camellia sinensis [L.] kuntze) plantation

A field experiment was conducted in the low country of Sri Lanka, during the period 1994–1995 to investigate the severity of weed infestation and tea growth in relation to weed management methods in newly established tea (Camellia sinensis[L.] Kuntze). Manual weeding (hand and slash weeding) at various intervals was compared with various herbicides, with or without mulching. Weed control with herbicides was superior to that of hand weeding at 6-week intervals or more. Weed control with oxyfluorfen at 0.29 kg ai ha−1 + paraquat at 0.17 kg ai ha−1 or glyphosate at 0.99 kg ai ha−1 + kaolin at 3.42 kg ha−1 were superior. Plots unweeded for 12 weeks or more produced significantly greater (P < 0.05) weed biomass than plots unweeded for 6 weeks. Although the least weed dry weight (P < 0.05) and the greatest number of weed species were recorded with hand weeding at 2 week intervals, there was no particular benefit on tea growth when compared with hand weeding at 6 and 12 week intervals. Inter row mulching in chemically treated plots was more favorable for tea growth than no mulching, while living weed cover in unmulched slash weeded plots suppressed tea growth. A combination of mulching and herbicides, particularly oxyfluorfen and paraquat, followed by hand weeding at least every 6–8 weeks was considered the most appropriate weed management system for young tea.