The plants commonly known as morning glory belong to the genera Ipomoea and Merremia and are among the most important weeds in Brazil. Greenhouse studies were conducted in 2016/2017 to compare the susceptibility of different morning glory species-Ipomoea quamoclit, I. nil, I. hederifolia, I. triloba, Merremia aegyptia, and M. cissoides to soil-applied herbicides and to evaluate the effectiveness of these herbicides after periods of drought. In the first experiment, to evaluate the efficacy of each herbicide at pre-emergence stage, a fully randomized 6 (doses) x 6 (species) factorial experimental design with six replicates was used. The herbicides tebuthiuron (3,200; 1,600; 800; 400; 200 and 0.0 g a.i ha-1), amicarbazone (2,100; 1,050; 750; 375; 187 and 0.0 g a.i ha-1), sulfentrazone (1,200; 600; 300; 150 75 and 0.0 g a.i ha-1), mesotrione (240; 120; 60; 30; 15 and 0.0 g a.i ha-1), saflufenacil (200; 100; 50; 25; 12 and 0.0 g a.i ha-1), and imazapic (360; 180; 90; 45; 22 and 0.0 g a.i ha-1) were applied. Ipomoea hederifolia, I. nil, and I. quamoclit were most susceptible to saflufenacil; I. triloba and M. cissoides were most susceptible to tebuthiuron; and M. aegyptia was most susceptible to amicarbazone. Therefore, the best herbicide treatment depends on the species of morning glory. In the second experiment, to determine the effectiveness of herbicides after periods of drought, the treatments were arranged, for each herbicide, in a fully randomized 6 x 5 factorial design with four replicates, six species of morning glory, and five sowing times after periods of drought (0, 15, 30, 45, and 60 days after application (DAA) of the herbicides) relative to the application of the amicarbazone (1,050 g a.i ha-1), imazapic (180 g a.i ha-1), mesotrione (120 g a.i ha-1), saflufenacil (100 g a.i ha-1), sulfentrazone (600 g a.i ha-1), and tebuthiuron (1,600 g a.i ha-1). Herbicide effectiveness after periods of drought began to decrease after 15 days for saflufenacil; 30 days for imazapic, mesotrione, and tebuthiuron; 45 days for amicarbazone; and 60 days for sulfentrazone. Preemergence application of amicarbazone and sulfentrazone exhibited consistent efficacy during the drought periods, satisfactorily controlling the species of morning glory.
A cana-de-açúcar tem grande importância econômica no Brasil. Para manter sua produtividade diversos fatores bióticos e abióticos podem influenciar positiva ou negativamente. Dentre eles, podem ser citados as plantas daninhas, os nematoides e a interação entre produtos fitossanitários para o controle de ambos. Em função disto, o presente trabalho teve como objetivo estudar a interação entre herbicidas e nematicidas usados na cultura da cana-de-açúcar. O delineamento experimental foi inteiramente casualizado em esquema fatorial 5 x 3, com 4 repetições. O primeiro fator corresponde aos herbicidas sulfentrazone (800 g ha-1 a.i.), saflufenacil (98 g ha-1 a.i.), diuron + hexazinone (1170 g ha-1 a.i. + 330 g ha-1 a.i.), amicarbazone (1050 g ha-1 a.i.), mais a testemunha; o segundo fator aos nematicidas benfuracarbe (2000 g ha-1 a.i.), carbofuran (1750 g ha-1 a.i.), mais a testemunha. Os nematicidas foram aplicados em contato com os toletes e os herbicidas aplicados em pré-emergência da cultura, sendo realizado nas variedades de cana-de-açúcar RB867515, RB975201 e RB975952. As avaliações de fitotoxicidade foram realizadas aos 7, 15, 30, 45 e 60 dias após a emergência (DAE) da cultura. Na última avaliação foram determinados os parâmetros biométricos altura, área foliar e biomassa seca da parte aérea. Todas as plantas se recuperaram aos 60 DAE, sendo que nos tratamentos com o uso do herbicida sulfentrazone foram observados sintomas mais elevados de intoxicação. Quanto aos parâmetros biométricos avaliados aos 60 DAE, não houve interação significativa para os fatores herbicida e nematicida, mas houve diferença entre os tratamentos em cada variedade.
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