Herbicides with potential use in the control of hairy fleabane and their selectivity in oats and ryegrass

Abstract

) e flumioxazin (50 e 100 g i.a. ha -1 ), além da testemunha (sem herbicida). Com exceção do herbicida imazethapyr, os demais foram seletivos à aveia branca, independentemente das doses avaliadas. Os herbicidas 2,4-D, diclosulam, saflufenacil e flumioxazin foram seletivos à cultura da aveia comum, quando aplicados na menor dose avaliada, sendo alternativas para o manejo de buva durante o inverno. O herbicida metsulfuron-methyl apresentou efeito tóxico sobre o azevém comum, diminuindo a massa de matéria seca da parte aérea (MMSPA). Para o azevém tetraploide, excetuando o imazethapyr e a maior dose de flumioxazin, os demais tratamentos mostraram-se seletivos. Embora alguns tratamentos tenham proporcionado sintomas de fitointoxicação, isso não refletiu negativamente na produção de MMSPA, evidenciando a capacidade de recuperação das plantas. Palavras-chave: Conyza bonariensis. Resistência de plantas daninhas. Pastagem de inverno. Lolium multiflorum. Avena spp.ABSTRACT -The rotation of herbicides is the main method used in the prevention and management of herbicide-resistant weeds. However, in addition to being efficient, herbicides should also be crop selective. The objective of this study was to evaluate the selectivity of herbicides with potential use in the control of hairy fleabane, to white oats, common oats, common ryegrass and tetraploid ryegrass. The experiments were arranged in a randomised-block design, in a bi-factorial scheme, with factor A comprising the herbicides, and factor B the herbicide doses X and 2X, where X is the recommended dose of the active ingredient (a.i.). The treatments to be evaluated were: 2,4-D amine (806 and 1,612 g a.i. ha ), as well as the control (no herbicide). Except for the herbicide imazethapyr, the other herbicides were selective to white oats, regardless of the dose. The herbicides 2,4-D, diclosulam, saflufenacil and flumioxazin were selective to common oats when applied at the lowest dose tested, being alternatives in the management of hairy fleabane during the winter. The herbicide metsulfuron-methyl had a toxic effect on common ryegrass, reducing shoot dry matter weight (SDW). Except for imazethapyr and the highest dose of flumioxazin, the remaining treatments were selective to tetraploid ryegrass. Although some treatments produced symptoms of phytotoxicity, this did not reflect negatively on the production of SDW, demonstrating the resilience of the plants.

Biomass Production and Mineral Nutrient Accumulation by Weeds and Sweet Orange Trees in the Amazonian

“…They were probably selected by the repetitive use of this herbicide. Currently, C. bonariensis is one of the most important weed species in Brazil and in the world (Heap, 2014;Dalazen, Kruse, & Machado, 2015) as a result of its characteristics: aggressiveness, wide geographic distribution and high capacity for herbicide resistance.…”