Pub Date : 2020-01-01DOI: 10.1590/s0100-83582020380100045
F. Frandoloso, L. Galon, G. Concenço, E. Rossetto, F. Bianchessi, C. O. Santin, C. T. Forte
ABSTRACT: The objective of this work was to evaluate the interference and to determine the level of economic damage (NDE) of the weed when infesting the corn crop. Treatments were composed by corn densities (2.60, 3.10, 3.65, 4.00 and 4.80 plants m-1) and 10 Alexandergrass populations for each crop seeding density. The population of plants, leaf area, soil cover and shoot dry mass of Alexandergrass were evaluated as indicator of infestation. Shoot dry mass of Alexandergrass presents better adjustment to the model of rectangular hyperbole, and losses of grain yield due to interference of the weed were satisfactorily estimated by this model. Corn sowing densities of 2.60; 3.10 and 3.65 plants m-1 in average, were more competitive of all evaluated variables in the presence of Alexandergrass. Corn densities of 2.60; 3.10 and 3.65 plants m-1 increase the level of economic damage, justifying the adoption of control measures of Alexandergrass when in higher populations. NDE values ranged from 1.58 to 9.37 plants m-2 at the densities of 4.00 and 4.80 maize plants m-1, which were less competitive with Alexandergrass.
{"title":"Interference and Level of Economic Damage of Alexandergrass on Corn","authors":"F. Frandoloso, L. Galon, G. Concenço, E. Rossetto, F. Bianchessi, C. O. Santin, C. T. Forte","doi":"10.1590/s0100-83582020380100045","DOIUrl":"https://doi.org/10.1590/s0100-83582020380100045","url":null,"abstract":"ABSTRACT: The objective of this work was to evaluate the interference and to determine the level of economic damage (NDE) of the weed when infesting the corn crop. Treatments were composed by corn densities (2.60, 3.10, 3.65, 4.00 and 4.80 plants m-1) and 10 Alexandergrass populations for each crop seeding density. The population of plants, leaf area, soil cover and shoot dry mass of Alexandergrass were evaluated as indicator of infestation. Shoot dry mass of Alexandergrass presents better adjustment to the model of rectangular hyperbole, and losses of grain yield due to interference of the weed were satisfactorily estimated by this model. Corn sowing densities of 2.60; 3.10 and 3.65 plants m-1 in average, were more competitive of all evaluated variables in the presence of Alexandergrass. Corn densities of 2.60; 3.10 and 3.65 plants m-1 increase the level of economic damage, justifying the adoption of control measures of Alexandergrass when in higher populations. NDE values ranged from 1.58 to 9.37 plants m-2 at the densities of 4.00 and 4.80 maize plants m-1, which were less competitive with Alexandergrass.","PeriodicalId":20102,"journal":{"name":"Planta Daninha","volume":"38 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67278806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.1590/s0100-83582020380100047
J. L. Pereira, R. R. Pereira, G. A. Resende-Silva, A. Jakelaitis, A. Silva, M. Picanço
This study aims to evaluate the impact of glyphosate-resistant soybean and its management with glyphosate on the canopy arthropod community. We study the direct impact of the insertion of the resistance gene and the indirect impact of management practices, specifically herbicide application. To do this, we use the following treatments: non-GM and GM soybean with mechanical weed control and GM soybean with one and three applications of glyphosate. Arthropods in the crop canopy were sampled over time in all treatments. The incorporation of the glyphosate resistance gene did not affect the richness and abundance of arthropods in the plant canopy. Glyphosate application reduced the richness of predators and chewing and sucking phytophagous arthropods in treatments with three herbicide applications. In the second season, total arthropod density was the lowest in transgenic soybean with three glyphosate applications. The density of Cerotoma arcuatus, a chewing phytophagous arthropod, followed similar trends, while both glyphosate treatments (one or three applications) reduced the densities of the predator Solenopsis sp. and the detritivore Hypogastrura sp. Meanwhile, the densities of the sucking phytophagous arthropods Bemisia tabaci, Caliothrips brasiliensis, and Tetranychus sp. were the highest in transgenic soybean with three glyphosate applications.
{"title":"Glyphosate Impact on Arthropods Associated to Roundup Ready and Conventional Soybean (Glycine max L.)","authors":"J. L. Pereira, R. R. Pereira, G. A. Resende-Silva, A. Jakelaitis, A. Silva, M. Picanço","doi":"10.1590/s0100-83582020380100047","DOIUrl":"https://doi.org/10.1590/s0100-83582020380100047","url":null,"abstract":"This study aims to evaluate the impact of glyphosate-resistant soybean and its management with glyphosate on the canopy arthropod community. We study the direct impact of the insertion of the resistance gene and the indirect impact of management practices, specifically herbicide application. To do this, we use the following treatments: non-GM and GM soybean with mechanical weed control and GM soybean with one and three applications of glyphosate. Arthropods in the crop canopy were sampled over time in all treatments. The incorporation of the glyphosate resistance gene did not affect the richness and abundance of arthropods in the plant canopy. Glyphosate application reduced the richness of predators and chewing and sucking phytophagous arthropods in treatments with three herbicide applications. In the second season, total arthropod density was the lowest in transgenic soybean with three glyphosate applications. The density of Cerotoma arcuatus, a chewing phytophagous arthropod, followed similar trends, while both glyphosate treatments (one or three applications) reduced the densities of the predator Solenopsis sp. and the detritivore Hypogastrura sp. Meanwhile, the densities of the sucking phytophagous arthropods Bemisia tabaci, Caliothrips brasiliensis, and Tetranychus sp. were the highest in transgenic soybean with three glyphosate applications.","PeriodicalId":20102,"journal":{"name":"Planta Daninha","volume":"38 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67278855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.1590/s0100-83582020380100092
Saulo F. B. Campos, João P. A.R. Cunha, Heli H.T. Assunção, Thales C. Alves, César H.S. Zandonadi, Ernane M.Lemes
Background: The use of electrostatic spray has the potential to optimize pesticide applications; however, further studies are required to verify its effectiveness. Objective: The objective of this work was to evaluate the electrostatic application system for the chemical control of weeds with glyphosate and adjuvant in different carrier volumes. Methods: The physicochemical properties of the spray solution, charge/mass relations, spray deposition on weeds, losses to the soil, effectiveness of weed control, and spray drift were evaluated. The field experiment was designed to have randomized blocks with four replications in a 2x2x2+2 factorial: the presence or not of electrostatic spray; with and without adjuvant (soybean lecithin + propionic acid); two carrier volumes (50 and 90 L ha-1); a control without applications and a conventional spray rate (150 L ha-1) for additional treatments. The study was performed in duplicate. Results: The electrostatic system energized the droplets during the application of glyphosate and adjuvant; however, this did not influence the deposition on the weeds, the losses to the soil, and the drift. The adjuvant improved the effectiveness of weed control in various situations, changed the spray solution properties, and reduced the losses due to drift. Conclusions: The adjuvant used proved to be an important tool in application technology. The effectiveness of weed control, in general, was not influenced by the electrostatic system.
背景:静电喷雾具有优化农药施用的潜力;然而，需要进一步的研究来验证其有效性。目的:评价不同载体体积下草甘膦和佐剂的静电施用体系对杂草的化学防治效果。方法:对喷雾溶液的理化性质、电荷/质量关系、喷雾在杂草上的沉积、对土壤的损失、防杂草效果和喷雾漂移进行评价。田间试验设计为随机分组，在2x2x2+2的阶乘中有4个重复:静电喷雾的存在与否;添加和不添加佐剂(大豆卵磷脂+丙酸);两个载体体积(50和90 L ha-1);一种是无应用的对照，另一种是常规喷雾量(150 L ha-1)。这项研究是重复进行的。结果:在草甘膦和佐剂的施用过程中，静电系统对液滴进行了通电;但是，这对杂草的沉积、土壤的损失和漂移没有影响。该助剂提高了各种情况下的除草效果，改变了喷雾溶液的性能，减少了因漂移造成的损失。结论:所使用的佐剂是应用技术的重要工具。除草效果一般不受静电系统的影响。
{"title":"Efficacy of glyphosate applied using an electrostatic sprayer as affected by adjuvant and carrier volumes","authors":"Saulo F. B. Campos, João P. A.R. Cunha, Heli H.T. Assunção, Thales C. Alves, César H.S. Zandonadi, Ernane M.Lemes","doi":"10.1590/s0100-83582020380100092","DOIUrl":"https://doi.org/10.1590/s0100-83582020380100092","url":null,"abstract":"Background: The use of electrostatic spray has the potential to optimize pesticide applications; however, further studies are required to verify its effectiveness. Objective: The objective of this work was to evaluate the electrostatic application system for the chemical control of weeds with glyphosate and adjuvant in different carrier volumes. Methods: The physicochemical properties of the spray solution, charge/mass relations, spray deposition on weeds, losses to the soil, effectiveness of weed control, and spray drift were evaluated. The field experiment was designed to have randomized blocks with four replications in a 2x2x2+2 factorial: the presence or not of electrostatic spray; with and without adjuvant (soybean lecithin + propionic acid); two carrier volumes (50 and 90 L ha-1); a control without applications and a conventional spray rate (150 L ha-1) for additional treatments. The study was performed in duplicate. Results: The electrostatic system energized the droplets during the application of glyphosate and adjuvant; however, this did not influence the deposition on the weeds, the losses to the soil, and the drift. The adjuvant improved the effectiveness of weed control in various situations, changed the spray solution properties, and reduced the losses due to drift. Conclusions: The adjuvant used proved to be an important tool in application technology. The effectiveness of weed control, in general, was not influenced by the electrostatic system.","PeriodicalId":20102,"journal":{"name":"Planta Daninha","volume":"1 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67279789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.1590/s0100-83582020380100030
Y. Abdullah, M. S. Baloch, A. Shah, M. M. Hashim, M. A. Nadim, G. Ullah, A. Khan, M. Shahzad
ABSTRACT: The present study was to assess the additive effects of cuscuta (akasbel) aqueous extract alone and in combination with full and reduced doses of commercially available weedicides against weeds in wheat crop during the year 2016-2017. The study was conducted in a randomized complete block design (RCBD) with 3 replications. The results showed that hand weeding and use of weedicides Allymax and Axial (full and half recommended doses) significantly controlled all prevailing weeds and increased yield and yield contributing parameters over the weedy check/control and sole application of cuscuta aqueous extract. Hand weeding and Allymax (full dose) showed minimum weed population, relative density, fresh and dry weed biomass and higher leaf area index (LAI), leaf area duration (LAD), crop growth rate (CGR), plant height, 1000 grain weight and grain yield while net assimilation rate (NAR), chlorophyll content, number of tillers, spike length, grains spike-1 and biological yield were maximum only in hand weeding. These findings suggest that in order to attain highest wheat yield, the field should be kept free from weeds by hand weeding (if labour is not a limiting factor) or use recommended dose of weedicide Allymax for efficient weed management in wheat.
{"title":"Weed Management in Wheat by Cuscuta Alone and in Combination with Commercial Weedicides Allymax and Axial","authors":"Y. Abdullah, M. S. Baloch, A. Shah, M. M. Hashim, M. A. Nadim, G. Ullah, A. Khan, M. Shahzad","doi":"10.1590/s0100-83582020380100030","DOIUrl":"https://doi.org/10.1590/s0100-83582020380100030","url":null,"abstract":"ABSTRACT: The present study was to assess the additive effects of cuscuta (akasbel) aqueous extract alone and in combination with full and reduced doses of commercially available weedicides against weeds in wheat crop during the year 2016-2017. The study was conducted in a randomized complete block design (RCBD) with 3 replications. The results showed that hand weeding and use of weedicides Allymax and Axial (full and half recommended doses) significantly controlled all prevailing weeds and increased yield and yield contributing parameters over the weedy check/control and sole application of cuscuta aqueous extract. Hand weeding and Allymax (full dose) showed minimum weed population, relative density, fresh and dry weed biomass and higher leaf area index (LAI), leaf area duration (LAD), crop growth rate (CGR), plant height, 1000 grain weight and grain yield while net assimilation rate (NAR), chlorophyll content, number of tillers, spike length, grains spike-1 and biological yield were maximum only in hand weeding. These findings suggest that in order to attain highest wheat yield, the field should be kept free from weeds by hand weeding (if labour is not a limiting factor) or use recommended dose of weedicide Allymax for efficient weed management in wheat.","PeriodicalId":20102,"journal":{"name":"Planta Daninha","volume":"38 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67278598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.1590/s0100-83582020380100064
Muhammad N. Zahoor, M. Nadeem, J. Iqbal, Muhammad F. Shahzad, T. Islam, Hussan A. Begum, Mohammad S. Baloch, Ayat Ullah
Background: Plant-derived compounds are alternatives of synthetic insecticides in sustainable agriculture. Objective: This study investigated the phytotoxic effect of higher concentrations (2, 4, 8 and 16%) of four plants extracts (Azadirachta indica, Mentha arvensis, D. stramonium and Citrus limonium) on cotton plants. Methods: Each concentration was replicated four times to check the phytotoxic effect (CO2-in, CO2-out, H2O-in, H2O-out and photosynthesis absorption rate (PAR) in randomized complete block design. Data was recorded after 12, 24, 48 and 72 hours of spray with the help of Photosynthetic CL 340 meter. Results: The results showed that CO2-in was more affected by the D. stramonium (131.65±0.38) at 8% concentration. The overall progress showed that C. limonium was more affected the CO2-in of cotton crop. CO2-out was less affected by the C. limonium (117.83±1.46) at 4% concentration than M. arvensis (116.99±1.25) at 8% concentration and D. stramonium (115.77±0.74) at 16% concentration, but was more affected by the A. indica (118.15±0.71) at 4%. H2O-in was more affected by the C. limonium (0.39±0.05) than D. stramonium, A. indica and M. arvensis at 16% concentration. H2O-out of cotton was least affected by the D. stramonium (7.63±0.01) at 2% and more affected by the C. limonium (1.56±0.15) at 16% concentration. PAR was more affected by the A. indica (931.47±8.39) at 4% concentration and least affected by the M. arvensis (1499.7±9.94) at 8% concentration. Conclusions: Different dosages of various botanicals influenced the opening and closing of stomata and photosynthesis of cotton plants.
{"title":"Phytotoxic effect of plant extracts on physiology of cotton (Gossypium hirsutum L.) plants","authors":"Muhammad N. Zahoor, M. Nadeem, J. Iqbal, Muhammad F. Shahzad, T. Islam, Hussan A. Begum, Mohammad S. Baloch, Ayat Ullah","doi":"10.1590/s0100-83582020380100064","DOIUrl":"https://doi.org/10.1590/s0100-83582020380100064","url":null,"abstract":"Background: Plant-derived compounds are alternatives of synthetic insecticides in sustainable agriculture. Objective: This study investigated the phytotoxic effect of higher concentrations (2, 4, 8 and 16%) of four plants extracts (Azadirachta indica, Mentha arvensis, D. stramonium and Citrus limonium) on cotton plants. Methods: Each concentration was replicated four times to check the phytotoxic effect (CO2-in, CO2-out, H2O-in, H2O-out and photosynthesis absorption rate (PAR) in randomized complete block design. Data was recorded after 12, 24, 48 and 72 hours of spray with the help of Photosynthetic CL 340 meter. Results: The results showed that CO2-in was more affected by the D. stramonium (131.65±0.38) at 8% concentration. The overall progress showed that C. limonium was more affected the CO2-in of cotton crop. CO2-out was less affected by the C. limonium (117.83±1.46) at 4% concentration than M. arvensis (116.99±1.25) at 8% concentration and D. stramonium (115.77±0.74) at 16% concentration, but was more affected by the A. indica (118.15±0.71) at 4%. H2O-in was more affected by the C. limonium (0.39±0.05) than D. stramonium, A. indica and M. arvensis at 16% concentration. H2O-out of cotton was least affected by the D. stramonium (7.63±0.01) at 2% and more affected by the C. limonium (1.56±0.15) at 16% concentration. PAR was more affected by the A. indica (931.47±8.39) at 4% concentration and least affected by the M. arvensis (1499.7±9.94) at 8% concentration. Conclusions: Different dosages of various botanicals influenced the opening and closing of stomata and photosynthesis of cotton plants.","PeriodicalId":20102,"journal":{"name":"Planta Daninha","volume":"1 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67279029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.1590/s0100-83582020380100044
S. Banaras, A. Javaid, A. Shoaib
ABSTRACT: Urdbean [Vigna mungo (L.) Hepper] is an important leguminous crop whose production is severely affected by charcoal rot disease caused by Macrophomina phaseolina. This study was undertaken to seek an environmental friendly alternative to synthetic fungicides for management of this disease. Dry biomass of an allelopathic weed Sonchus oleraceous L. was used to combat the menace. Fumigated sandy loam pot soil, pre-inoculated with M. phaseolina, was amended with different doses of dry biomass of the weed ranging from 0.5% to 3%. Application of 2% weed biomass completely controlled the disease. Soil inoculation with M. phaseolina inoculation (positive control) reduced shoot dry weight and grain yield of urdbean by 59% and 91%, respectively, over negative control. Application of different doses of soil amendment in pathogen inoculated soil enhanced shoot dry weight and grain yield of urdbean by 107-307% and 438-7400%, respectively, over positive control. The highest positive effect on growth and yield of uedbean in M. phaseolina contaminated soil was recorded due to 2.5% amendment. M. phaseolina inoculation significantly enhanced peroxidase (POX) and phenyl alanine ammonia lyase (PAL) activities. However, application of different doses of S. oleraceous biomass to the soil gradually decreased activities of these enzymes. The present study concludes that application of 2.5% dry biomass of S. oleraceous can completely control charcoal rot of urdbean and significantly enhance crop growth and yield.
{"title":"Non-Chemical Control of Charcoal Rot of Urdbean by Sonchus oleraceous Application","authors":"S. Banaras, A. Javaid, A. Shoaib","doi":"10.1590/s0100-83582020380100044","DOIUrl":"https://doi.org/10.1590/s0100-83582020380100044","url":null,"abstract":"ABSTRACT: Urdbean [Vigna mungo (L.) Hepper] is an important leguminous crop whose production is severely affected by charcoal rot disease caused by Macrophomina phaseolina. This study was undertaken to seek an environmental friendly alternative to synthetic fungicides for management of this disease. Dry biomass of an allelopathic weed Sonchus oleraceous L. was used to combat the menace. Fumigated sandy loam pot soil, pre-inoculated with M. phaseolina, was amended with different doses of dry biomass of the weed ranging from 0.5% to 3%. Application of 2% weed biomass completely controlled the disease. Soil inoculation with M. phaseolina inoculation (positive control) reduced shoot dry weight and grain yield of urdbean by 59% and 91%, respectively, over negative control. Application of different doses of soil amendment in pathogen inoculated soil enhanced shoot dry weight and grain yield of urdbean by 107-307% and 438-7400%, respectively, over positive control. The highest positive effect on growth and yield of uedbean in M. phaseolina contaminated soil was recorded due to 2.5% amendment. M. phaseolina inoculation significantly enhanced peroxidase (POX) and phenyl alanine ammonia lyase (PAL) activities. However, application of different doses of S. oleraceous biomass to the soil gradually decreased activities of these enzymes. The present study concludes that application of 2.5% dry biomass of S. oleraceous can completely control charcoal rot of urdbean and significantly enhance crop growth and yield.","PeriodicalId":20102,"journal":{"name":"Planta Daninha","volume":"17 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67278772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.1590/s0100-83582020380100010
A. Rehman, R. Qamar, M. Safdar, H. Javeed, M. Shehzad, M. Ali, M. Asif, Z. H. Tarar, A. Ahmed, M. Jamil
ABSTRACT: Weed-induced yield loss in wheat crop is a great threat to food security in Pakistan. A comprehensive understanding of weed-crop competition is very important to develop sustainable and cost-effective weed management. For this purpose, two-year field studies were conducted to determine the effect of different blessed milkthistle densities on the phenology and yield of wheat crop in a rice-wheat cropping scheme in Sargodha, Pakistan during 2013-2014 and 2014-2015. The experiment comprised seven treatments: control (weed free), weedy check (weedy without any control) and blessed milkthistle densities of 5, 10, 15, 20 and 25 plants m-2. In response to increasing weed density, a gradual reduction in yield and yield-related traits of wheat was noted. Compared to the weed-free control, a significant reduction in number of productive tillers m-2 (20% and 18%), plant height (15% and 18%), spike length (19% and 26%), number of grains spike-1 (23% and 26%), 1000 grain weight (28% and 28%), grain (29% and 30%) and biological (20% and 24%) yields of wheat occurred at and beyond blessed milkthistle density of 5 plants m-2 during 2013-2014 and 2014-2015 respectively. It can be concluded that blessed milkthistle weed must be controlled if its population density reaches 5 plants m-2 in order to avoid significant grain yield losses in wheat.
{"title":"Understanding the Competitive Effects of Blessed Milkthistle Densities on Wheat","authors":"A. Rehman, R. Qamar, M. Safdar, H. Javeed, M. Shehzad, M. Ali, M. Asif, Z. H. Tarar, A. Ahmed, M. Jamil","doi":"10.1590/s0100-83582020380100010","DOIUrl":"https://doi.org/10.1590/s0100-83582020380100010","url":null,"abstract":"ABSTRACT: Weed-induced yield loss in wheat crop is a great threat to food security in Pakistan. A comprehensive understanding of weed-crop competition is very important to develop sustainable and cost-effective weed management. For this purpose, two-year field studies were conducted to determine the effect of different blessed milkthistle densities on the phenology and yield of wheat crop in a rice-wheat cropping scheme in Sargodha, Pakistan during 2013-2014 and 2014-2015. The experiment comprised seven treatments: control (weed free), weedy check (weedy without any control) and blessed milkthistle densities of 5, 10, 15, 20 and 25 plants m-2. In response to increasing weed density, a gradual reduction in yield and yield-related traits of wheat was noted. Compared to the weed-free control, a significant reduction in number of productive tillers m-2 (20% and 18%), plant height (15% and 18%), spike length (19% and 26%), number of grains spike-1 (23% and 26%), 1000 grain weight (28% and 28%), grain (29% and 30%) and biological (20% and 24%) yields of wheat occurred at and beyond blessed milkthistle density of 5 plants m-2 during 2013-2014 and 2014-2015 respectively. It can be concluded that blessed milkthistle weed must be controlled if its population density reaches 5 plants m-2 in order to avoid significant grain yield losses in wheat.","PeriodicalId":20102,"journal":{"name":"Planta Daninha","volume":"38 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67278034","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.1590/s0100-83582020380100054
Debora C. Cabrera, M. T. Sobrero, M. Pece, S. Chaila
Background: Megathyrsus maximus (Jacq.) is a perennial weed that affects many crops. In Argentina, sugarcane is the most affected. Objective: Study effective techniques to break dormancy and the effect of environmental factors on the germination of this weed. Methods: Experiments were carried out in cabinet incubators twice, with five replicates per treatment. The experimental unit was made up for 50 seeds. Results: Seed dormancy was strongly associated with the presence of glumes. Manual extractions of glumes and immersion in sulphuric acid were the most effective techniques for breaking dormancy. Megathyrsus maximus did not depend on light to germinate, and it did so both under a 12 h-light-dark photoperiod and in complete darkness, with maximum mean germination percentages of 73 and 76%, respectively. Mean germination percentage (G) and coefficient of germination (CG: number of germinated seeds per day) showed that this weed responded to a wide range of temperatures, the optimal varied between 25 and 35 °C. Both mean germination percentages and CG decreased as osmotic potential became increasingly negative (0 MPa to -0.6 MPa), and as sodium chloride solution concentrations increased (10 to 130 mmol L-1). No germination was observed at -0.8 MPa and with a 150 mmol L-1 sodium chloride solution. Conclusions: The optimal germination conditions for M. maximus can be found in central sugarcane areas in Argentina, since soils are in ideal conditions and are kept under irrigation. In marginal areas, M. maximus germination would depend on rainfall and certain sodium chloride concentrations in the soil.
{"title":"Effect of environmental factors on the germination of Megathyrsus maximus: an invasive weed in sugarcane in Argentina","authors":"Debora C. Cabrera, M. T. Sobrero, M. Pece, S. Chaila","doi":"10.1590/s0100-83582020380100054","DOIUrl":"https://doi.org/10.1590/s0100-83582020380100054","url":null,"abstract":"Background: Megathyrsus maximus (Jacq.) is a perennial weed that affects many crops. In Argentina, sugarcane is the most affected. Objective: Study effective techniques to break dormancy and the effect of environmental factors on the germination of this weed. Methods: Experiments were carried out in cabinet incubators twice, with five replicates per treatment. The experimental unit was made up for 50 seeds. Results: Seed dormancy was strongly associated with the presence of glumes. Manual extractions of glumes and immersion in sulphuric acid were the most effective techniques for breaking dormancy. Megathyrsus maximus did not depend on light to germinate, and it did so both under a 12 h-light-dark photoperiod and in complete darkness, with maximum mean germination percentages of 73 and 76%, respectively. Mean germination percentage (G) and coefficient of germination (CG: number of germinated seeds per day) showed that this weed responded to a wide range of temperatures, the optimal varied between 25 and 35 °C. Both mean germination percentages and CG decreased as osmotic potential became increasingly negative (0 MPa to -0.6 MPa), and as sodium chloride solution concentrations increased (10 to 130 mmol L-1). No germination was observed at -0.8 MPa and with a 150 mmol L-1 sodium chloride solution. Conclusions: The optimal germination conditions for M. maximus can be found in central sugarcane areas in Argentina, since soils are in ideal conditions and are kept under irrigation. In marginal areas, M. maximus germination would depend on rainfall and certain sodium chloride concentrations in the soil.","PeriodicalId":20102,"journal":{"name":"Planta Daninha","volume":"38 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67278695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.1590/s0100-83582020380100055
Bruno M. Silva, Renan R. Zandoná, Roberto C. A. Neto, Jonathan Torchelsen, D. Agostinetto
and the lack of selective herbicides registered for birdsfoot trefoil crops affect their development and limit their productivity. Objective: This study aimed to evaluate selectivity of post-emergent herbicides for weed control in birdsfoot trefoil crops. Methods: Experiments were carried out in a greenhouse and on a field, in both vegetative and reproductive development stages of birdsfoot trefoil crops. Treatments were composed of post-emergent herbicides recommended for soybean, corn and garlic cultivation. Phytotoxicity (PHYTO), plant height (HEI), shoot dry matter (SDM) and root dry matter (RDM) were evaluated. Data were submitted to the analysis of variance and when means were significant, they were compared by the Duncan’s Test (p≤0.05). In order to determine post-emergent herbicides which were selective to the crop, those that provided PHYTO below or equal to 15% were recommended, since they did not significantly interfere with morphological variables HEI, SDM and RDM, by comparison with the control. Results: Unlike results found in the vegetative stage, birdsfoot trefoil plants were more tolerant to phytotoxic effects of herbicides imazethapyr, chlorimuron-ethyl, cloransulam-methyl and fomesafen in the reproductive stage. The variables were negatively affected by the herbicides bentazon, glyphosate and carfentrazone-ethyl, with PHYTO higher than 40% at 20 days after treatment in
{"title":"Selectivity of post-emergent herbicides for weed control in birdsfoot trefoil crops","authors":"Bruno M. Silva, Renan R. Zandoná, Roberto C. A. Neto, Jonathan Torchelsen, D. Agostinetto","doi":"10.1590/s0100-83582020380100055","DOIUrl":"https://doi.org/10.1590/s0100-83582020380100055","url":null,"abstract":"and the lack of selective herbicides registered for birdsfoot trefoil crops affect their development and limit their productivity. Objective: This study aimed to evaluate selectivity of post-emergent herbicides for weed control in birdsfoot trefoil crops. Methods: Experiments were carried out in a greenhouse and on a field, in both vegetative and reproductive development stages of birdsfoot trefoil crops. Treatments were composed of post-emergent herbicides recommended for soybean, corn and garlic cultivation. Phytotoxicity (PHYTO), plant height (HEI), shoot dry matter (SDM) and root dry matter (RDM) were evaluated. Data were submitted to the analysis of variance and when means were significant, they were compared by the Duncan’s Test (p≤0.05). In order to determine post-emergent herbicides which were selective to the crop, those that provided PHYTO below or equal to 15% were recommended, since they did not significantly interfere with morphological variables HEI, SDM and RDM, by comparison with the control. Results: Unlike results found in the vegetative stage, birdsfoot trefoil plants were more tolerant to phytotoxic effects of herbicides imazethapyr, chlorimuron-ethyl, cloransulam-methyl and fomesafen in the reproductive stage. The variables were negatively affected by the herbicides bentazon, glyphosate and carfentrazone-ethyl, with PHYTO higher than 40% at 20 days after treatment in","PeriodicalId":20102,"journal":{"name":"Planta Daninha","volume":"4 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67278729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.1590/s0100-83582020380100048
R. Córdova, M. Tomazetti, J. P. Refatti, D. Agostinetto, L. A. Avila, E. Camargo
ABSTRACT: This study aimed to evaluate the potential for glyphosate drift during aerial application using rice plants as sentinels, aiming to determine the effect of drift on irrigated rice crops. For this purpose, a field experiment was performed using an entirely randomized design with four replicates, evaluating different distances from the site of application [control (no application), 0, 12.5, 25, 50, 75, 100, 150, 200, 300, and 400 m]. The experiment was carried out at the Granjas 4 Irmãos farm, located in the Rio Grande city, Rio Grande do Sul State, Brazil. The glyphosate dose application was 1,920 g e.a. ha-1 (Roundup Transorb®, 480 g e.a. L-1 glyphosate isopropylamine salt). A dose-response curve was developed to estimate the drift rate in sentinel plants, by applying increasing glyphosate doses in rice plants and assessing the injury level. The drift rates estimated by the injury level in sentinel plants were 14% (150 m), 13% (200 m), and 5% (400 m). Death of the experimental units was observed for distances between 0 and 50 m, while in distances between 75 and 150 m, 25 to 50% of the plants survived, reducing productivity. In the distances between 200 and 400 m, there was no reduction in productivity when compared to the control, even when the injury levels reached 52 to 82%. Thus, we concluded that a 5% glyphosate drift reached up to 400 m from the application range. Considering the recommendation of zero drift, distances greater than 400 m should be adopted to avoid symptoms in rice plants. We suggest using distances of more than 400 m in future studies.
{"title":"Drift Distance in Aircraft Glyphosate Application Using Rice Plants as Indicators","authors":"R. Córdova, M. Tomazetti, J. P. Refatti, D. Agostinetto, L. A. Avila, E. Camargo","doi":"10.1590/s0100-83582020380100048","DOIUrl":"https://doi.org/10.1590/s0100-83582020380100048","url":null,"abstract":"ABSTRACT: This study aimed to evaluate the potential for glyphosate drift during aerial application using rice plants as sentinels, aiming to determine the effect of drift on irrigated rice crops. For this purpose, a field experiment was performed using an entirely randomized design with four replicates, evaluating different distances from the site of application [control (no application), 0, 12.5, 25, 50, 75, 100, 150, 200, 300, and 400 m]. The experiment was carried out at the Granjas 4 Irmãos farm, located in the Rio Grande city, Rio Grande do Sul State, Brazil. The glyphosate dose application was 1,920 g e.a. ha-1 (Roundup Transorb®, 480 g e.a. L-1 glyphosate isopropylamine salt). A dose-response curve was developed to estimate the drift rate in sentinel plants, by applying increasing glyphosate doses in rice plants and assessing the injury level. The drift rates estimated by the injury level in sentinel plants were 14% (150 m), 13% (200 m), and 5% (400 m). Death of the experimental units was observed for distances between 0 and 50 m, while in distances between 75 and 150 m, 25 to 50% of the plants survived, reducing productivity. In the distances between 200 and 400 m, there was no reduction in productivity when compared to the control, even when the injury levels reached 52 to 82%. Thus, we concluded that a 5% glyphosate drift reached up to 400 m from the application range. Considering the recommendation of zero drift, distances greater than 400 m should be adopted to avoid symptoms in rice plants. We suggest using distances of more than 400 m in future studies.","PeriodicalId":20102,"journal":{"name":"Planta Daninha","volume":"38 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67278912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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