Mammalian Cell Cytotoxicity Analysis of Soybean Rust Fungicides (original) (raw)
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International Fungicide Efficacy Trials for the Management of Soybean Rust
Plant Disease, 2007
The efficacy of fungicides in managing soybean rust was evaluated in 12 environments in South America and southern Africa over three growing seasons from 2002 to 2005. There were differences in final soybean rust severity, defoliation, and yield among the treatments at most locations. In locations where soybean rust was not severe, all the fungicides evaluated reduced severity. In locations where soybean rust was severe, applications of triazole and triazole + strobilurin fungicides resulted in lower severity and higher yields compared with other fungicides. The strobilurin fungicides provided the highest yields in many locations; however, severity tended to be higher than that of the triazole fungicides. There also were differences in yield and severity between the trials with two and three applications of several fungicides, with three applications resulting in less severe soybean rust and higher yields. However, the third application of tebuconazole, tetraconazole, and the mixtur...
Journal of Agricultural Science
Asian soybean rust (ASR) caused by Phakopsora pachyrhizi since it was first reported in Brazil in 2001 has been subject of studies regarding the use of fungicides to its control. Low efficiency of triazol (demethylator inhibitors-DMI’s) or stobilurin (quinone outside inhibitor-QoI’s) has been reported on the control of ASR under field conditons. For this reason experiments were conducted to study the effects of these systemic fungicides associate with protectant multi-site fungicides (MSF) on ASR control preventively and at the onset of the epidemic. All combinations of fungicides were effective to control ASR and promoted greater soybean yield gain compared to the control. The analysis of the efficacy of ASR control in the lower, medium and upper part of the plant canopy, showed that application of Epoxiconazole + Pyraclostrobin and Cyproconazole + Azoxystrobin reduced ASR and leaf fall (%), and increased soybean yield grain. The severity of the disease increased from t...
Fungicide management in the Asian soybean rust
Asian soybean rust is the major crop disease and the management of the use of the fungicide is important for effective control. The objective of this work was to evaluate the management of fungicides with sequential applications to control Asian soybean rust. The experimental design used was a randomized block with four replications and eight treatments with different combinations of fungicides from the following chemical groups: triazole, strobilurin, carboxamide, and dithiocarbamate. The applications were carried out with backpack spray equipment at constant pressure (CO 2) and a spray rate of 200 L ha-1. The severity of rust, the area under the disease progress curve, control efficiency, mass of 1,000 grains, and productivity were evaluated. The protective fungicide mancozeb, in mixtures with systemic fungicides, were more effective for the control of Asian soybean rust than the systemic fungicides applied without the protective fungicide.
Quantitative review of fungicide efficacy trials for managing soybean rust in Brazil
With the arrival of Asian soybean rust (caused by Phakopsora pachyrhizi) in the Western Hemisphere in 2001, field research to optimize chemical control of this important yield-limiting disease has proliferated. We present a meta-analytical synthesis of the results of 71 uniform fungicide trials containing 930 entries (specific fungicidal treatments) conducted in Brazil from 2003Brazil from /2004Brazil from to 2006Brazil from /2007. Our objectives were to: (1) quantify the overall efficacy of fungicidal treatments in reducing disease and yield loss; (2) determine to what extent fungicide efficacy depends on overall disease pressure, the number of spray applications, and the amount of disease present at the time of the first application; and (3) test for differences in efficacy among fungicide classes and specific active ingredients. Weighted median response ratios for disease severity (R S ) and yield (R Y ) were 0.413 and 1.439, respectively, indicating that, on average, fungicide treatments reduced disease by 58.7% (range: À38.9-100%) and increased yield by 43.9% (range: À21.8-458%). Response ratios were dependent on disease pressure (expressed as disease severity of the untreated check), with the greatest reduction in rust severity (i.e., lowest R S values) observed for low disease pressure and the best yield response (i.e., highest R Y values) observed for high disease pressure. In trials where both one and two application schedules were included, R S and R Y were better for entries receiving two applications than for one application. In w65% of entries across all trials, disease was present at the time of the first application, albeit at low levels (median ¼ 0.20% severity). Only disease severities of up to 0.05% at the time of the first application could be tolerated without affecting R S negatively, whereas presence of any disease at the first application had a negative effect on R Y , even when disease pressure was low. In general, triazole fungicides applied alone performed better than strobilurins alone, but there was a wide range in efficacy among individual triazoles, with prothioconazole and tebuconazole performing best and fluquinconazole and difenoconazole being least effective. Combinations of strobilurins with triazoles (especially those containing cyproconazole) improved disease and yield loss control compared with either class alone. In contrast, combinations of triazoles with a benzimidazole fungicide did not improve R S or R Y compared with triazoles alone. Across fungicides, R Y and R S were correlated negatively (r ¼ À0.6296, P ¼ 0.0017), indicating that treatments with better disease control also had higher yields.
Evaluation of Fungicides to Control Asian Rust and Anthracnose in Soybean
Journal of Agricultural Studies, 2019
Soybean (Glicine max L.) is one of the most important crops from the economic standpoint for Brazil and due to the favorable climate for the development of fungal diseases, requires special needs. The fungal diseases with the greatest economic impact on Brazilian culture are Asian rust, caused by the fungus Phakopsora pachyrhizi and Anthracnose, caused by Colletotrichum truncatum. Together, without proper control, they can be devastating. Fungicides represent a high cost to producers, however, necessary for productivity losses do not decrease production. In this way, obtaining a combination of fungicides that provides results for the control of the diseases, from the beginning of the infestation period, with a satisfactory cost benefit is of the utmost importance to Brazilian producers. The objective of this study was to evaluate the combination of six commercial fungicides (APROACH PRIMA®, SPHERE MAX®, FOX®, FUSÃO®, ELATUSTM and ORKESTRA) and sequential applications in the control ...
Effect of Fungicide and Timing of Application on Soybean Rust Severity and Yield
Plant Disease, 2009
Soybean rust, caused by Phakopsora pachyrhizi, is a devastating foliar disease of soybean that may cause significant yield losses if not managed by well-timed fungicide applications. To determine the effect of fungicide timing on soybean rust severity and soybean yield, field trials were completed in Paraguay (four locations), the United States (two locations), and Zimbabwe (one location) from 2005 to 2006. Treatments at each location included applications of tebuconazole, pyraclostrobin, or a combination of azoxystrobin + propiconazole, and in some locations pyraclostrobin + tebuconazole at the following soybean growth stages (GS): (i) GS R1 (beginning flowering), (ii) GS R3 (beginning pod), (iii) GS R5 (beginning seed), (iv) GS R1 + R3, (v) GS R3 + R5, and (vi) GS R1 + R3 + R5. Soybean yields from plots treated with fungicides were 16 to 114% greater than yields from no fungicide control plots in four locations in Paraguay, 12 to 55% greater in two locations in the United States, ...
Tropical Plant Pathology, 2014
The objectives of this study were to evaluate the influence of soybean cultivar of two maturity groups, early/semi-early (E) or intermediate (I), on the management of Asian soybean rust (ASR) with fungicides and yield. Field trials were conducted during the 2006/07 and 2007/08 growing seasons. Seven cultivars of the two groups were tested in the first season and eight in the second season. All cultivars had plots that were treated (T) or non-treated (NT) with a commercial mixture of pyraclostrobin + epoxiconazole. ASR severity (%) was visually assessed several times during the crop cycle and yield (kg ha -1 ) was determined at harvest. Values of the standardized area under the disease progress curve (AUDPC) calculated from the severity assessments was higher in 2007/08 than in 2006/07, but no differences were found between cultivars of the E and I maturity groups. Differences in yield between between T and NT plots were lower in cultivars of the E group than those of the I group in both the 2006/07 (37.6% and 52.8% respectively) and the 2007/08 season (56.9% and 85.0%, respectively). A higher stability in yield was found for cultivars of the E maturity group compared to those of the I group.
How to cope with the vulnerability of site specific fungicides on the control of Asian soybean rust
International journal of research in agronomy, 2021
Asian soybean rust (ASR) caused by Phakopsora pachyrhizi is the most important disease of the crop. The pathogen is highly aggressive under field conditions when the environmental conditions favor the disease development. The disease was first described in Japan, in 1902 and in 1914, it had already spread to several countries in Southeast Asia.). The first report in South America was made in Brazil in 1979 in wild soybeans and later in 2001 in the soythern area of the country in comercial plantations. P. pachyrhizi can naturally infect a wide range of plant species, including 41 species in 17 genera of the Fabaceae family. The symptoms of the disease can be seen on the abaxial and eventually on the adaxial surface of the lesions. In susceptible varieties the number of uredia per lesion varies from four to eight and the latent period around seven days. P. pachyrhizi requires more than 8 hours a day of continuous leaf wetness, and the optimal temperature for maximum germination around 22 o C. There is no varieties with complete resistance to the disease available to planting. The main method of control of the disease is the application of fungicides. The main groups of fungicides to control the disease belongs to the demetilation inhibitores (DMI's), quinone outside inhibitor (QoI's) and carboxamides (SDHI). But with the continuous spraying with DMI's and QoI's alone to control ASR resistant mutants of P. pacHIhyrhizi multiplied in the population over the country. The use of mixture of DMI'S with QoI's in the beginning proportioned resonable controle of the disease. But few years latter P. pachyrhizi acquired resistance to the mixture of triazol with stobolurins. Then it was introduced the carboxamide group (SDHI) to use in mixture with triazol with stobolurins. The triple mixture was then recommended for more a few years giving good results. Finally researchers decided to incorporate multisite fungicides in a mixture with triazol, strobilurin and or carboxamide to minimize the probability to build up resistant mutants in the population of P. pachyrhizi. The addition of multisite fungicides in a mixture with site specific is very important to reinforce the fight against fungal resistance. In conclusion to cope with the vulnerability of P. pachyrhizi to site specific fungicides the strategy has to involve integration of measures such as sanitary vacuum, rotation of a mixture of different biochemical mechanisms of action plus multisite, avoid sequential and curative applications, use of early cultivars and sowing at the beginning of the recommended season, eliminate voluntary soybean plants from the field, use of fungicides in the onset of preventively at least once before the planting lines closed, sowing at the beginning of the recommended season, and use of cultivars with resistance gene (s) to reduce the number of spraying. The present overview discuss how difficult is to cope with the resistance of P. pachyrhizi to site specific fungicides.
Journal of Agricultural Science
It has been a growers concen the reduction of Asian soybean rust (ASR) control by commercial fungicide co-formulations in the last growing seasons in southern Brazil. The objective of this work was to assess the ASR control efficacy by the most used co-formulations in the 2018/19 season. In a field experiment, 19 fungicides in commercial formulations to control soybean rust caused by Phakopsora pachyrhizi, were evaluated. Chemicals at their recommended doses were sprayed at four soybean growth stages. The first application was performed with 1.82% leaflet incidence and coinciding with R1 phenological stage. The others were performed at 14-18 days intervals. At stage R6, end of the epidemic and coinciding with half of the defoliation in the control plots, the leaf severity was appraised. The experiment was conducted with Ativa soybean cultivar, in 3 × 6 m plots, four replications and randomized block design. The harvest was made with a plot combine and the yield expressed in grains k...