Search

Brazil stands out in the world for being one of the largest producers and consumers of common beans and cowpeas. However, the cultivation of this agricultural species is exposed to competition with weeds for water, light and nutrients. One of the management methods for weed control is the use of pre-emergent herbicides. Although pre-emergence herbicides are beneficial in controlling weeds, it is important to know the dynamics of these products in the soil, especially their residual effect. Two experiments were carried out to assess the tolerance of bean genotypes to the pre-emergent herbicide S-metolachlor in two Brazilian soils. Bean genotypes have differential tolerance to S-metolachlor when grown in soils with different characteristics. The Vigna spp. were the most affected by S-metolachlor, especially the red Adzuki. Plant growth was more sensitive when grown in sandy soil for most species. Total chlorophyll content was not affected for most genotypes in the two soils evaluated. The differential tolerance of the genotypes in both soils confirms the potential of S-metolachlor to cause damage to the bean crop, especially in sandy soil. The S-metolachlor was efficient in controlling sourgrass and selective to the bean cultivars (Pérola and Talismã) in both soils evaluated. Alexandergrass behaved differently in the soils evaluated, showing tolerance to the application of S-metolachlor when in Oxisol and sensitivity in Ultisol. [ABSTRACT FROM AUTHOR]

The prevalence of Huanglongbing (HLB) disease, also known as citrus greening, has compelled the citrus industry to change management practices to increase production. However, these changes, such as enhanced nutrition and irrigation programs, have caused weed proliferation, subsequently leading to increased use of herbicides. Thus, our study evaluated a popular preemergence herbicide active ingredient, diuron, for nontarget impacts on young Hamlin and Valencia sweet orange (Citrus sinensis L. Osbek) trees in two commercial orchards in southwest Florida. The treatments included the preemergence application of diuron at three rates (1.8, 3.6, and 7.3 kg a.i./ha), a weed-checked control (using postemergence herbicides: glufosinate ammonium + saflufenacil), and a nontreated control. The treatments were applied twice (in Fall 2021 and Spring 2022) in a randomized complete block with four replicates. Results indicate that over a 5-month period, the application of diuron generally had no significant impact on citrus root growth. Further, over a 2-month observation period for Hamlin and a 4-month observation period for Valencia, it was found that diuron application had no notable effect on fruit detachment force. Valencia trees treated with diuron high showed higher HLB disease severity at location 1. In addition, Hamlin trees treated with diuron low and medium showed higher fruit drop (~19% more) than the untreated control at location 1. However, this trend was inconsistent across the locations and cultivars. This result suggests that increased disease severity and fruit drop were not associated with diuron treatment. Thus, our study finds diuron as a tree-safe option for preemergence weed suppression in citrus production, as long as it is used in accordance with the recommended dosage and restrictions stated on the herbicide label. [ABSTRACT FROM AUTHOR]

The prevalence of Huanglongbing (HLB) disease, also known as citrus greening, has compelled the citrus industry to change management practices to increase production. However, these changes, such as enhanced nutrition and irrigation programs, have caused weed proliferation, subsequently leading to increased use of herbicides. Thus, our study evaluated a popular preemergence herbicide active ingredient, diuron, for nontarget impacts on young Hamlin and Valencia sweet orange (Citrus sinensis L. Osbek) trees in two commercial orchards in southwest Florida. The treatments included the preemergence application of diuron at three rates (1.8, 3.6, and 7.3 kg a.i./ha), a weed-checked control (using postemergence herbicides: glufosinate ammonium + saflufenacil), and a nontreated control. The treatments were applied twice (in Fall 2021 and Spring 2022) in a randomized complete block with four replicates. Results indicate that over a 5-month period, the application of diuron generally had no significant impact on citrus root growth. Further, over a 2-month observation period for Hamlin and a 4-month observation period for Valencia, it was found that diuron application had no notable effect on fruit detachment force. Valencia trees treated with diuron high showed higher HLB disease severity at location 1. In addition, Hamlin trees treated with diuron low and medium showed higher fruit drop (∼19% more) than the untreated control at location 1. However, this trend was inconsistent across the locations and cultivars. This result suggests that increased disease severity and fruit drop were not associated with diuron treatment. Thus, our study finds diuron as a tree-safe option for preemergence weed suppression in citrus production, as long as it is used in accordance with the recommended dosage and restrictions stated on the herbicide label.

Brazil stands out in the world for being one of the largest producers and consumers of common beans and cowpeas. However, the cultivation of this agricultural species is exposed to competition with weeds for water, light and nutrients. One of the management methods for weed control is the use of pre-emergent herbicides. Although pre-emergence herbicides are beneficial in controlling weeds, it is important to know the dynamics of these products in the soil, especially their residual effect. Two experiments were carried out to assess the tolerance of bean genotypes to the pre-emergent herbicide S-metolachlor in two Brazilian soils. Bean genotypes have differential tolerance to S-metolachlor when grown in soils with different characteristics. The Vigna spp. were the most affected by S-metolachlor, especially the red Adzuki. Plant growth was more sensitive when grown in sandy soil for most species. Total chlorophyll content was not affected for most genotypes in the two soils evaluated. The differential tolerance of the genotypes in both soils confirms the potential of S-metolachlor to cause damage to the bean crop, especially in sandy soil. The S-metolachlor was efficient in controlling sourgrass and selective to the bean cultivars (Pérola and Talismã) in both soils evaluated. Alexandergrass behaved differently in the soils evaluated, showing tolerance to the application of S-metolachlor when in Oxisol and sensitivity in Ultisol.

Roundup Ready 2 Xtend® [glyphosate- and dicamba-resistant (DR)] soybean is a novel trait option for postemergence (POST) control of herbicide-resistant broadleaf weeds in soybean. With increased use of labeled dicamba products POST in DR soybean and recommendations to include a soil-residual herbicide POST (e.g., layered residual approach), research on how combinations of these approaches influence weed control, weed seed production, and soybean grain yield is warranted. The objective of this research was to evaluate the effects of (1) flumioxazin applied preemergence (PRE) followed by (fb) dicamba plus glyphosate applied POST at different crop developmental stages and (2) acetochlor POST as a layered residual approach on weed control, weed seed production, and soybean yield to determine the optimal POST timing in DR soybean. A field study was conducted in Wisconsin at three sites in 2018 and four sites in 2019 to evaluate flumioxazin (43.4 g ai ha−1, WDG 51%) PRE fb dicamba (560 g ae ha−1, SL) plus glyphosate (1,101 g ae ha−1, SL) POST in DR soybean at three stages: early-POST (EPOST, V1-V2), mid-POST (MPOST, V3-V4), and late-POST (LPOST, V5-V6/R1) with or without a soil-residual herbicide POST (acetochlor, 1,262 g ai ha−1, ME). Weed community composition was site-specific; difficult-to-control broadleaf species included giant ragweed (Ambrosia trifida L.) and waterhemp [Amaranthus tuberculatus (Moq.) J.D. Sauer]. Dicamba plus glyphosate applied MPOST and LPOST provided greater control, weed biomass reduction, and density reduction of giant ragweed and waterhemp when compared with EPOST treatments. Giant ragweed and waterhemp had not reached 100% cumulative emergence at EPOST, and plants that emerged after EPOST produced seed. There was some benefit to including acetochlor as a layered residual at EPOST as indicated by a residual by POST timing interaction for waterhemp density reduction. Complete waterhemp control was not attained at one site-year. For remaining site-years, dicamba plus glyphosate applied MPOST (V3-V4) provided season-long weed control, reduced weed seed production, and optimized soybean grain yield compared with other POST treatments. Results highlight the importance of timely POST applications and suggest utilization of a POST layered residual needs to be timed appropriately for the window of active weed species emergence.

Pre-emergent herbicides have been developed for their long residual effect; however, they can make sensitive successor cultures unfeasible. Waste remediation techniques are needed for sustainable agricultural systems; for this, the edaphoclimatic asymmetries in the country must be considered. This study aimed to evaluate the remedial capacity of the herbicide diclosulam by covering crops under different edaphoclimatic conditions. Treatments were arranged in an n × 2 factorial scheme, the first factor being the number of plant species in each location and the second being the presence or absence of diclosulam in the soil. The physiological and growth characteristics of 15 potential phytoremediation species were evaluated. Herbicide residues in the environment were positively correlated with the soil pH; organic matter, aluminum, and silt contents; and aluminum saturation. The effectiveness of phytoremediation varied between species and between regions. Plant species suitable for efficient phytoremidation systems of diclosulam residues were Canavalia ensiformis for Couto Magalhães de Minas, Cajanus cajan and Canavalia ensiformis for Diamantina, Raphanus sativus for Erechim and Cajanus cajan for São João Evangelista. [ABSTRACT FROM AUTHOR]

Abstract Background: Fleabane plants (Conyza spp.) resistant to glyphosate herbicide are found infesting areas in the Central-West and Southeast regions of Brazil, but its management is not a concerning problem for summer crops in these regions as in the South region of Brazil. Objective: To evaluate the management of adult fleabane plants at the summer soybean crop and off-season (autumn-winter), monitoring new emergences to assess the dynamics of plants from November 2018 to March 2020, and the residual effect of herbicides applied at the end of the rainy season in the Cerrado biome, in Brasília, DF, Brazil. Methods: Four field experiments were developed from November 06, 2018 to April 02, 2020; all under randomized block design, with four replications, in factorial or split-plot arrangement, with visual weed control evaluations (0% to 100%) and seedling counting. Results: The highest fleabane infestations in soybean crops were found before sowing, and were partially or fully controlled by pre-sowing chemical/management treatments, which did not interfere with the soybean seed yield. The fleabane biological cycle ended in November-December (1st year), and December-January (2nd year). Conclusions: The most significant fleabane emergence in the areas was found in February and March. The treatments with saflufenacil and glufosinate-ammonium, followed by 2,4-D, were the most efficient and fastest control of adult fleabane plants.

Abstract Vegetable producers are often concerned about potential herbicide carryover and injury to vegetables following the application of livestock manure/compost from animals fed with treated hay. A greenhouse study was conducted to evaluate the effect of activated charcoal on soil residual activity of the herbicides aminopyralid, aminocyclopyrachlor, and picloram, applied at recommended field rates of 120 g ae, 70 g ai, and 303 g ai ha−1 respectively, on tomato, okra, and cantaloupe. A commercial source of activated charcoal was used at four rates [0, 0.5X, 1X, and 2X (1X = 336 kg ha−1)]. When no activated charcoal was applied, aminopyralid caused the greatest injury to tomato and okra, leading to plant death at 4 weeks after emergence/transplanting (WAE/T). At the highest rate (2X) of activated charcoal, crop injuries due to aminopyralid were reduced by 72 and 78% for okra and cantaloupe, respectively at 4 WAE, while tomato did not respond to the 2X rate of activated charcoal. For aminocyclopyrachlor, even a much lower rate (0.5X) of activated charcoal was sufficient to reduce about 70% of the injury caused on cantaloupe and okra. For picloram, activated charcoal application at the 2X rate reduced injury by 78–94% across the three vegetable species investigated. Under low herbicide residue levels that usually occur under carryover situations, a much lower rate of activated charcoal (<100 kg ha−1) may be sufficient and practically feasible. Overall, activated charcoal application shows promise for remediating soil contaminated with herbicide residues, but crop response can be variable and requires optimization for specific herbicide, species, and use scenarios. Highlights • Tomato was the most sensitive species to carryover from pasture herbicides, compared to okra and cantaloupe. • Activated charcoal (AC) reduced injuries caused by aminopyralid, aminocyclopyrachlor, and picloram; greater injury reduction with higher rates. • AC at a rate of 168 kg/ha was sufficient to remediate aminocyclopyrachlor injury but higher rates were required for aminopyralid and picloram. • The remediation potential provided by activated charcoal application was influenced by application rate, herbicide, and vegetable species. [ABSTRACT FROM AUTHOR]

Graphical abstract Pulsed micro-discharge ambient ionization mass spectrometry was developed for direct surface analysis. Highlights • Pulsed micro-discharge ambient ionization MS was developed for direct analysis. • The source with simple apparatus requires no solvent and auxiliary gas. • Sharp tip reduces the discharge volume and results in a crater of 60 μm in diameter. • Sensitive detection and imaging of atrazine infiltrated in plant tissue was achieved. Abstract A method named pulsed micro-discharge ambient ionization mass spectrometry (PMD-AIMS) was developed for direct surface analysis with simple apparatus. In PMD-AIMS, micro-discharges is generated between a copper plate and a tungsten needle with pulsed high voltage applied, in which the analyte on the surface of copper plate is desorbed and ionized, then drawn to the inlet of the mass spectrometer. In this experiment, the tungsten needle was fabricated via an electrochemical method with sharp apex to reduce the volume of the discharge. The experimental parameters were optimized to achieve a high sensitivity and high spatial resolution for mass spectrometry imaging. LOD (S/N = 3) was determined to be 20 ng/ml for atrazine on the yam and 1 ng/ml for atrazine on the copper plate with a lateral resolution of 60 μm. The PMD-AIMS technique was further applied for the rapid detection of the residual herbicide on epidermis. The distribution of the herbicide in plant tissue was investigated with mass spectrometry imaging. The results indicate that PMD-AIMS is a sensitive analytical technique with the capability of mass spectrometry imaging. [ABSTRACT FROM AUTHOR]

The combined use of desiccant and residual herbicides is a common management practice under no-tillage systems. However, the effect of desiccant herbicides and mulch on the leaching of residual herbicide is unknown. This study aimed at assessing the leaching of the S-metolachlor herbicide applied to ryegrass sequentially or in association with paraquat or glyphosate. A randomized blocks design was used, with four repetitions and treatments distributed over split-plots. The desiccant herbicides paraquat (600 g ha-1) or glyphosate (720 g ha-1) were used in the main plot, while S-metolachlor (2,800 g ha-1) was applied sequentially or in association with the desiccant herbicides in the subplots. There was also a control containing only desiccant herbicide, with no application of residual herbicide. The type of desiccant did not affect the leaching of the residual herbicide. In addition, the chosen method to apply the residual herbicide, sequentially or in association with the desiccant, did not impact the S-metolachlor behavior in the soil. The bioavailable concentration in the soil, 25 days after the application, was 90 g a.i. ha-1, at a depth of 18 cm.

Residual sulfentrazone may remain in the soil for around two years, being a source of groundwater contamination and preventing the growth of susceptible plants. So, phytoremediation may represent an option for decontaminating areas which were highly affected by applications of this herbicide. This study aimed at evaluating the potential of Crotalaria juncea, Canavalia ensiformis, Cajanus cajan and Cajanus cajan (dwarf) for remediation of soil contaminated with sulfentrazone, using millet (Pennisetum glaucum) as a bioindicator plant. The experiment was installed in a greenhouse and treatments consisted of the four species already mentioned, plus a control, and four sulfentrazone doses (0 g a.i. ha-1, 200 g a.i. ha-1, 400 g a.i. ha-1 and 800 g a.i. ha-1). Plants height, phytotoxicity to sulfentrazone and fresh and dry matter were evaluated. When P. glaucum was grown after C. juncea, the fresh and dry matter, as well as plant height, were higher, while the phytotoxicity symptoms were less evident. C. juncea showed the best results for phytoremediation of soils contaminated with sulfentrazone.

Copyright of Agricultural Research in the Tropics / Pesquisa Agropecuária Tropical is the property of Pesquisa Agropecuaria Tropical and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A interferência de convolvuláceas na produtividade dos cultivares de soja (Coodetec 206 e Monsoy 6101) semeados diretamente sob a palha residual (12,8 t ha-1) de cana crua foi estudada em relação aos manejos com o herbicida diclosulam (0,035 kg ha-1) em mistura em tanque com glyphosate (1,440 kg ha-1), aplicados na operação de dessecação da cana-de-açúcar, diclosulam isolado (0,035 kg ha-1), em pré-emergência da cultura da soja, e fomesafen (0,250 kg ha¹), em pós-emergência. Para isso, utilizou-se delineamento experimental de blocos casualizados, num esquema fatorial 2x5, com oito repetições. Observou-se pelos resultados que a utilização do herbicida diclosulam isoladamente e em mistura com o glyphosate promoveu controle eficaz das plantas daninhas. A infestação das cordas-de-viola não foi capaz de interferir negativamente nas características de crescimento das plantas, havendo apenas diferenças estatísticas entre os cultivares. As características de produção também não sofreram interferências negativas, exceto quanto à massa seca de 100 sementes no cultivar Monsoy 6101. Este cultivar Monsoy 6101 apresentou-se mais adequado para utilização dentro do período de renovação dos canaviais, por atingir o estádio R8 (colheita) nove dias antes.A field trial was conducted to evaluate the chemical control of Convolvulaceae weeds in soybean fields under sugar-cane rotation. The sugar-cane was harvested without burning with a layer of straw on the soil surface. The herbicides evaluated were: diclosulam plus glyphosate (0.035 + 1.440 kg ha-1, tank mix) during pre-crop and weed dissection, diclosulam alone (0.035 kg ha-1) on soybean preemergence and fomesafen (0.250 kg ha-1) on soybean postemergence. In the field the plots were arranged in a completely randomized block design, and the treatments in a 2x5 factorial design, the factors consisting of two soybean cultivars (Coodetec 206 and Monsoy 6101) and five weed management measures (weedy, weed free, diclosulam, fomesafen and diclosulam + glyphosate). The results showed that the weed densities were not sufficient to reduce soybean productivity. Diclosulam and its mixture with glyphosate provided good control of the convolvulaceae species: Ipomoea grandifolia, Ipomoea quamoclit and Merremia cissoides. The cultivar Monsoy 6101 was considered the most suitable for sugarcane rotation due to its shorter cycle.

Conduziu-se um ensaio em campo na Estação Experimental Agronômica da Universidade Federal do Rio Grande do Sul, em Eldorado do Sul, RS, em 1989/90. O objetivo foi determinar o efeito dos herbicidas clomazone, chlorimuronethyl, imazaquin e imazethaphyr, aplicados em três doses à superfície do solo (PRE) ou incorporados no mesmo (PPI), sobre o rendimento de aquênios de girassol e seus componentes. Os herbicidas de solo para controle de plantas daninhas na cultura da soja com maior potencial de dano ao girassol cultivado em sucessão, conforme indicado pelo rendimento de aquênios, foram os seguintes, em ordem decrescente: imazaquin > clomazone > imazethapyr> chlorimuron-ethyl. O efeito mais pronunciado dos herbicidas foi a redução da população de plantas. Este foi o fator que mais influenciou no rendimento do girassol.A field experiment was carried-out during 1989/90 at the Eldorado do Sul Experimental Station of Federal University of "Rio Grande do Sul", Brazil, with the objective of evaluating the effect of clomazone, chlorimuron-ethyl, imazaquin and imazethapyr applied at three different dosages in pre-emergence (PRE) or preplant incorporated (PPI), on sunflower achene yield and its components. Herbicide injury potential, as indicated by sunflower yield, was the following, from more to less phytotoxic: imazaquin > clomazone > imazethapyr > chlorimuron-ethyl. The main effect of the herbicides was in sunflower stand reduction, and this was the main yield component which was affected.

Conduziu-se um ensaio em campo na Estação Experimental Agronômica da Universidade Federal do Rio Grande do Sul, em Eldorado do Sul, RS, em 1989/90. O objetivo do trabalho foi determinar o efeito residual potencial dos herbicidas imazaquin e imazethapyr, aplicados em três doses à superfície do solo (PRE) ou incorporados no mesmo (PPI), na cultura de girassol. Num sistema de rotação soja-girassol, o efeito residual potencial de imazaquin foi mais acentuado que o de imazethapyr. A atividade herbicida de imazaquin e imazethapyr não foi dependente do método de aplicação. Imazaquin e imazethapyr, nas maiores doses, promoveram danos iniciais acentuados. As plantas de girassol recuperaram-se dos sintomas de intoxicação de imazethapyr, os quais diminuíram com o decorrer do tempo, mas não se recuperaram das injúrias causadas pelas maiores doses de imazaquin.A field experiment was carried-out during 1989/90 at the Eldorado do Sul Experimental Station of Federal University of "Rio Grande do Sul", Brazil, with the objective of evaluating potential injury to sunflower by imazaquin and imazethapyr applied at three different dosages in pre-emergence (PRE) or preplant incorporated (PPI). In a soybeansunflower rotation, imazaquin presents greater potential injury to sunflower than imazethapyr. Imazaquin and imaze thapyr activities were not dependent on application method. It occurred severe herbicide injury when sunflower was assessed early in the season. Plant height assessed late in the season indicated that sunflower recovered from imazethapyr injury, but not from imazaquin injury.

Conduziu-se um ensaio de campo na Estação Experimental Agronômica da Universidade Federal do Rio Grande do Sul, em Eldorado do Sul, RS em 1989/90. O objetivo do trabalho foi determinar o efeito residual potencial do herbicida chlorimuron-ethyl aplicado em três doses à superficie do solo (PRE) ou incorporado no mesmo (PPI), sobre a cultura de girassol. A atividade de chlorimuron-ethyl (etil 2-((((4-cloro-6-metoxipirimidina-2 il)amino)carbonil)amino)sulfonil)benzoato) não foi dependente de sua posição no solo. Chlorimuron-ethyl promoveu injúria inicial acentuada, constatando-se pouca ou nenhuma resposta ao aumento da dose para matéria seca da parte aérea do girassol, área foliar e estatura das plântulas. Contudo, avaliação de estatura das plantas, realizada na maturação fisiológica, indicou que os danos promovidos pelo herbicida reduziram-se com o decorrer do tempo. Concluiu-se que, aparentemente, num sistema de sucessão soja-girassol, o efeito residual potencial de chlorimuron-ethyl ao girassol é pequeno.A field experiment was carried out during 1989/90 at the Eldorado do Sul Experimental Station of Federal University of Rio Grande do Sul, Brazil with the objective of evaluating potencial injury to sunflower by chlorimuron-ethyl applied at three different dosages in pre-emergence (PRE) or preplant incorporated (PPI). Chlorimuron-ethyl activity was not dependent on the application method. Early in the season there were higher levels of injury to the plants, with little or no response to dosages with regard to shoot weight, leaf area and seedling size. However, plant height assessed late in the season indicated recovery from initial symptoms. Apparently, chlorimuron-ethyl injury to sunflower is limited in a rotation soybean-sunflower.

Conduziu-se um ensaio de campo na Estação Experimental Agronômica da Universidade Federal do Rio Grande do Sul, em Eldorado do Sul, RS, em 1989/90. O objetivo deste trabalho foi determinar o efeito residual potencial do herbicida clomazone, aplicado em três doses à superfície do solo (PRE) ou incorporado no mesmo (PPI), sobre a cultura de girassol. Através de ensaio complementar, realizado em casa-de-vegetação em 1990, procurou-se determinar o local de absorção de clomazone por plântulas de girassol. A localização de clomazone no solo foi muito importante na determinação de sua injúria para o girassol. A campo, clomazone promoveu injúria mais acentuada nas plântulas, quando aplicado em PRE do que em PPI. Clomazone, aparentemente, foi mais absorvido pelo hipocótilo do que pelo sistema radicular das plantulas de girassol. No entanto, nas maiores doses, a fitotoxicidade em PPI se acentuou com o decorrer do tempo, a ponto de desaparecerem as diferenças entre épocas de aplicação.A field experiment was carried out during 1989/90 at the Eldorado do Sul Experimental Station of Federal University of Rio Grande do Sul, Brazil, with the objective of evaluating potential injury to sunflower by clomazone applied at three different dosages in pre-emergence (PRE) or preplant incorporated (PPI). A greenhouse trial was carried out in 1990 to determine the site of uptake for clomazone from the soil. Clomazone placement in the soil was very important in determining the level of injury to the plants. The leved of injury to seedlings was higher when clomazone was sprayed in PRE as compared to PPI. Apparently, more clomazone was absorbed through the sunflower hypocotyl than by the root system. Late season assessments indicated that higher dosages were equally phytotoxic under both application methods.

Copyright of Agricultural Research in the Tropics / Pesquisa Agropecuária Tropical is the property of Pesquisa Agropecuaria Tropical and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Herbicides are commonly used globally. However, residual herbicides in soils for ages often result in phytotoxicity and serious yield loss to subsequent crops. In this paper, the multi-walled carbon nanotubes (MWCNTs) were utilized to amend the herbicide polluted soil, and the adsorption performance of herbicides to MWCNTs amended soil was studied. Results indicate efficient alleviation of herbicide-induced phytotoxicity to rice and tobacco due to MWCNTs amendment. When 0.4% MWCNTs were applied, the concentration of sulfentrazone that inhibited the same rice height by 50% (IC 50) increased to more than 3 times that of pure soil. When the MWCNTs were used to alleviate the phytotoxicity of quinclorac to tobacco, the MWCNTs not only alleviated the phytotoxicity of quinclorac but also promoted the growth of tobacco. The MWCNTs amended soil significantly increased the adsorption of herbicide to soil than biochar. The soil microbial analysis shows that MWCNTs had no significant effect on soil microbial community diversity, but the long-term exposure to MWCNTs could change the structure of the soil microbial community. Above all, our results highlighted the potential implication of the MWCNTs to ensure crop production by promoting crop growth and reducing the residual bioavailability of herbicides. • The MWCNTs are better than biochar to alleviate the phytotoxicity of herbicides. • MWCNTs simultaneously promote the growth of tobacco. • The phytotoxicity alleviation was due to the reduced bioavailable concentration. • The K d or K f of MWCNTs amended soil can be calculated from the logistic equation. • MWCNTs long-term exposure did not change soil microbial diversity but the structure. [ABSTRACT FROM AUTHOR]

The article focuses on the study on reliability of direct seeding for revegetation in the Central West of New South Wales. The study stated factors considered in the unreliability of direct seeding in Central West of New South Wales include prolonged dry periods since 1990, lack of a defined winter wet season, and limited knowledge of soil properties. The study conducted 12 treatments, which includes various herbicides treatment, and various pre-sowing components including rip, scalp, and scarify. Results have shown plant growth was affected by below-average rainfall.

Abstract: In glyphosate-tolerant maize, a delay in glyphosate application may be required to ensure late germinating weeds do not reach reproductive maturity. Alternatively, full season weed control may be achieved by frequent applications of glyphosate throughout the growing season. Another approach that may improve weed control and aid in the stewardship of glyphosate use is to apply a pre-emergence residual herbicide prior to one in-crop application of glyphosate. There is limited information on the optimal glyphosate application timing in glyphosate-tolerant maize (Zea mays) following the application of a residual herbicide. Six factorial field trials were conducted over a 2 year period (1999 and 2000) at two Ontario locations, Ridgetown, and Woodstock to evaluate the efficacy of the residual herbicide flufenacet plus metribuzin applied preplant, pre-emergence or at the maize spike stage followed by a post-emergence application of glyphosate in glyphosate-tolerant maize. At Ridgetown, crop tolerance was acceptable at all flufenacet plus metribuzin, glyphosate and flufenacet plus metribuzin followed by glyphosate application timings. Visual crop injury of up to 40% was recorded at Woodstock after the application of flufenacet plus metribuzin. Control of Amaranthus retroflexus, Ambrosia artemisiifolia, and Chenopodium album with flufenacet plus metribuzin followed by an in-crop application of glyphosate was better than with one in-crop application of glyphosate. The application timing of glyphosate and flufenacet plus metribuzin was not a significant factor in weed control or grain yield. In maize, the application of a residual herbicide such as flufenacet plus metribuzin prior to glyphosate may provide better early season weed control and allow for the delayed in-crop application of glyphosate. [Copyright &y& Elsevier]