<b>Fomesafen toxicity to bean plants as a function of the time of application and herbicide dose

Abstract

ABSTRACT. The objectives of the present study were to evaluate the impact of the time of fomesafen application and its dose on the tolerance of the common bean crop and to investigate the influence of environmental variables on herbicide selectivity. Two field experiments were conducted using the time of fomesafen application and its dose as factors. Crop injury from fomesafen reached 20% when evaluated one week after treatment (WAT). When sprayed at the warmest times of the day when irradiance levels were at their highest (11:00 am and 4:00 pm), fomesafen phytotoxicity was higher compared with other application times. Increased values of these two environmental variables, especially luminosity, was associated with high levels of fomesafen injury to the bean crop. However, assessments made at three WAT demonstrated that the crop had recovered from its initial injuries.Keywords: environmental variables, air temperature, luminosity, selectivity.Toxicidade de fomesafen às plantas de feijão em função dos horários de aplicação e das doses do herbicida RESUMO. Os objetivos do presente estudo foram avaliar o impacto do horário de aplicação de fomesafen e suas doses sobre a tolerância da cultura do feijão e investigar a influência de variáveis ambientais sobre a seletividade do herbicida. Dois experimentos a campo foram conduzidos usando os horários de aplicação de fomesafen e suas doses como fatores. Injúria de fomesafen na cultura chegou a 20% quando avaliada uma semana após o tratamento (SAT). Quando aspergido nos horários mais quentes do dia, quando os níveis de irradiância foram mais elevados (11h00 e 16h00), a fitotoxicidade de fomesafen foi maior comparada aos outros horários de aplicação. Aumento nos valores dessas duas variáveis ambientais, especialmente a luminosidade, foi associado com elevados níveis de injúria de fomesafen ao feijoeiro. No entanto, as avaliações realizadas aos três SAT demonstraram que a cultura havia recuperado de suas injúrias iniciais.Palavras-chave: variáveis ambientais, temperatura do ar, luminosidade, seletividade.

Fluazifop-P-Butyl Efficacy as a Function of Application Time and Herbicide Dose

“…The conceptual map organizing the correlation coefficients among all the dependent variables determined in this work (Figure 3) may suggest a causal relationship among these variables (Cieslik et al, 2014). Indeed, in this conceptual map, the paths with highest significance (thickest lines) may the causal explanations for the performance of fluazifop in U. plantaginea.…”

“…The environmental variables during the herbicide spray are affected by the time of the day. Therefore, the time of the day which the herbicide is sprayed may affect the herbicide efficacy (Cieslik et al, 2014). There is enough theoretical knowledge about the impact of the environment on the efficacy of ACCase inhibitors (Cieslik et al, 2013).…”

“…There is limited information about how fluazifop performance is affected by environmental conditions actually measured under field situations. Experiments evaluating dose-response curves of herbicides sprayed in several times of the day provide a good opportunity to determine the interaction among environmental variables and their effect on herbicide efficacy (Cieslik et al, 2014). The objectives of this work were to identify the time of fluazifop application which gives best performance of U. plantaginea control in the common bean crop and to determine the environmental variables most important for the efficacy of this herbicide.…”

“…Environmental conditions, such as air temperature and relative humidity, as well as irradiation, affect several steps on the herbicide-plant interaction, mainly interception, absorption and the translocation of the chemical within the weed (Cieslik et al, 2013(Cieslik et al, , 2014. The environmental variables during the herbicide spray are affected by the time of the day.…”

“…The control of vegetation with herbicides is one of the main tactics of weed management (Lamego et al, 2011;Kalsing and Vidal, 2012;Cieslik et al, 2014). The plant of Urochloa plantaginea (Brachiaria plantaginea) is a grass weed with annual life cycle and reproduction by seeds.…”