Eficácia do imazapyr no controle de plantas daninhas e seu impacto sobre plantas não alvo
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2020-11-06
Autores
Pereira, Pâmela Castro
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Universidade Estadual Paulista (Unesp)
Resumo
Os objetivos deste trabalho foram avaliar a eficácia de imazapyr no controle de plantas daninhas e o impacto de subdoses em plantas não alvo. Os experimentos para eficácia das plantas daninhas foram conduzidos em condições de casa de vegetação, em delineamento inteiramente casualizado. As espécies utilizadas foram Cynodon dactylon, Digitaria horizontalis, Digitaria insularis, Eleusine indica, Ipomoeae purpurea, Panicum maximum e Uroclhoa decumbens, que foram semeadas em vasos (10x14,5), preenchidos com mistura de solo e substrato orgânico (1:1). As doses testadas foram: 66,5; 133,1; 266,3; 399,4; 532,5 e 665,7 g i.a ha-1 mantendo-se testemunha e dez repetições. A aplicação em pré-emergência ocorreu 3 dias após a semeadura e a aplicação em pós-emergência, quando as plantas estavam com 2 a 3 perfilhos. As avaliações foram realizadas em 3, 7, 15, 21, 30, 45 e 60 dias após a aplicação, avaliando a eficácia (pós) e a inibição de emergência (pré). No final do experimento mensuro-se a massa fresca e massa seca. Os experimentos para avaliar o impacto das subdoses para plantas não alvo foram conduzidos em casa de vegetação, em delineamento inteiramente casualizado, as plantas testes terrestres avaliadas foram: Cucurbita pepo abóbrinha, Lactuca sativa, Oryza sativa, Phaseolus vulgaris e Arachis hypogaea; as plantas testes aquáticas Hydrocotyle ranunculoides e Lemna minor; e mudas pré-brotadas de cana-de-açúcar. As subdoses utilizadas de imazapyr foram 1,0; 4,15; 16,60 e 66,5 g i.a ha-1, com dez repetições para terrestre e cinco para aquática e uma testemunha. O herbicida foi aplicado em pós-emergência das plantas testes e em pré e pós plantio das mudas pré brotadas de cana-de-açúcar. As avaliações foram realizadas em 3,7,14 e 21 dias após a aplicação para as plantas testes terrestres e aquáticas. E 1,3,7,14,21,30 e 45 dias após a aplicação para mudas pré brotadas de cana-de-açúcar, avaliando os sinais de intoxicação e no final do experimento comprimento da parte aérea e radicular, massa fresca e massa seca. O herbicida aplicado em pré emergência das plantas daninhas é mais eficaz, pois para todas as plantas ele apresentou controle excelente e em pós emergência aos 45 DAA a partir da dose 266,5 g i.a ha-1 apresentou controle excelente para as plantas C. dactylon, D. horizontalis, D. insularis e P. maximum. Para C. pepo, P. vulgaris e cana-de-açúcar (pré e pós) as subdoses de imazapyr causaram intoxicação visual gradual com o aumento das doses. Para L. sativa e H. ranunculoides, houve poucos sinais de intoxicação, e para O. sativa, A. hypogaea e L. minor ocorreu efeito hormético. Conclui-se que o imazapyr aplicado em pré emergência é mais eficaz para o controle de C. dactylon, D. horizontalis, D. insularis, E. indica, I. purpurea, P. maximum e U. decumbens e a deriva de imazapyr, pode causar tanto injurias quanto hormese em plantas não alvo, a depender da espécie e da concentração do herbicida a que cada planta é exposta.
The objectives were to evaluate the effectiveness of imazapyr in controlling weeds and the impact of underdoses on non-target plants. The experiments for weed efficacy were conducted in greenhouse conditions, in a completely randomized desig. The species used were Cynodon dactylon, Digitaria horizontalis, Digitaria insularis, Eleusine indica, Ipomoeae purpurea, Panicum maximum and Uroclhoa decumbens, which were sown in pots (10x14,5), filled with a mixture of soil and organic substrate (1: 1). The doses tested were: 66.5; 133.1; 266.3; 399.4; 532.5 and 665.7 g i.a ha-1, maintaining control and ten repetitions. The pre-emergence application occurred 3 days after sowing and the post-emergence application, when the plants were 2 to 3 tillers. The evaluations were performed at 3, 7, 15, 21, 30, 45 and 60 days after application, evaluating the effectiveness (post) and emergency inhibition (pre), at the end of the experiment measured fresh and dry mass. The experiments to assess the impact of underdoses for non-target plants were carried out in a greenhouse, in a completely randomized design, the ground test plants evaluated were: Cucurbita pepo zucchini, Lactuca sativa, Oryza sativa, Phaseolus vulgaris and Arachis hypogaea; the aquatic test plants Hydrocotyle ranunculoides and Lemna minor; and pre-sprouted sugarcane seedlings. The subdoses used for imazapyr were 1.0; 4.15; 16.60 and 66.5 g i.a ha-1, with ten repetitions for terrestrial and five for aquatic and one control. The herbicide was applied in post-emergence of the test plants and in pre and post planting of presprouted sugarcane seedlings. The evaluations were carried out in 3,7,14 and 21 days after the application for the terrestrial and aquatic tests plants. E 1,3,7,14,21,30 and 45 days after application for pre-sprouted sugarcane seedlings, evaluating the signs of intoxication and at the end of the experiment aerial and root length, fresh mass and mass dry. The herbicide applied in weeds pre emergencies is more effective, because for all plants it showed excellent control and in post emergence at 45 DAA from the dose 266.5 g ia ha-1 it showed excellent control for C. dactylon plants , D. horizontalis, D. insularis and P. maximum. For C. pepo, P. vulgaris and sugar cane (pre and post) imazapyr underdoses caused gradual visual intoxication with increasing doses. For L. sativa and H. ranunculoides, there were few signs of intoxication, and for O. sativa, A. hypogaea and L. minor there was a hormone effect. It is concluded that imazapyr applied in pre-emergence is more effective for the control of C. dactylon, D. horizontalis, D. insularis, E. indica, I. purpurea, P. maximum and U. decumbens and the imazapyr drift, it can cause both injuries and hormones in non-target plants, depending on the species and concentration of the herbicide to which each plant is exposed.
The objectives were to evaluate the effectiveness of imazapyr in controlling weeds and the impact of underdoses on non-target plants. The experiments for weed efficacy were conducted in greenhouse conditions, in a completely randomized desig. The species used were Cynodon dactylon, Digitaria horizontalis, Digitaria insularis, Eleusine indica, Ipomoeae purpurea, Panicum maximum and Uroclhoa decumbens, which were sown in pots (10x14,5), filled with a mixture of soil and organic substrate (1: 1). The doses tested were: 66.5; 133.1; 266.3; 399.4; 532.5 and 665.7 g i.a ha-1, maintaining control and ten repetitions. The pre-emergence application occurred 3 days after sowing and the post-emergence application, when the plants were 2 to 3 tillers. The evaluations were performed at 3, 7, 15, 21, 30, 45 and 60 days after application, evaluating the effectiveness (post) and emergency inhibition (pre), at the end of the experiment measured fresh and dry mass. The experiments to assess the impact of underdoses for non-target plants were carried out in a greenhouse, in a completely randomized design, the ground test plants evaluated were: Cucurbita pepo zucchini, Lactuca sativa, Oryza sativa, Phaseolus vulgaris and Arachis hypogaea; the aquatic test plants Hydrocotyle ranunculoides and Lemna minor; and pre-sprouted sugarcane seedlings. The subdoses used for imazapyr were 1.0; 4.15; 16.60 and 66.5 g i.a ha-1, with ten repetitions for terrestrial and five for aquatic and one control. The herbicide was applied in post-emergence of the test plants and in pre and post planting of presprouted sugarcane seedlings. The evaluations were carried out in 3,7,14 and 21 days after the application for the terrestrial and aquatic tests plants. E 1,3,7,14,21,30 and 45 days after application for pre-sprouted sugarcane seedlings, evaluating the signs of intoxication and at the end of the experiment aerial and root length, fresh mass and mass dry. The herbicide applied in weeds pre emergencies is more effective, because for all plants it showed excellent control and in post emergence at 45 DAA from the dose 266.5 g ia ha-1 it showed excellent control for C. dactylon plants , D. horizontalis, D. insularis and P. maximum. For C. pepo, P. vulgaris and sugar cane (pre and post) imazapyr underdoses caused gradual visual intoxication with increasing doses. For L. sativa and H. ranunculoides, there were few signs of intoxication, and for O. sativa, A. hypogaea and L. minor there was a hormone effect. It is concluded that imazapyr applied in pre-emergence is more effective for the control of C. dactylon, D. horizontalis, D. insularis, E. indica, I. purpurea, P. maximum and U. decumbens and the imazapyr drift, it can cause both injuries and hormones in non-target plants, depending on the species and concentration of the herbicide to which each plant is exposed.
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Deriva, Herbicidas, Inibidor ALS, Manejo, Monitoramento ambiental, Intoxicação