Herbicide selectivity in alfalfa crops

Abstract

-This study aimed to determine the selectivity of herbicides applied in pre-and post-emergence for alfalfa crops. Three separate experiments were carried out under greenhouse conditions. The first experiment was arranged in a completely randomized design with three replications in a 4 x 11 + 1 factorial scheme , with eleven herbicides (bentazon, chlorimuron-ethyl, fomesafen, fluazifop-p-butyl, saflufenacil, imazethapyr, clethodim, nicosulfuron, imazaquin, haloxyfop-methyl and MSMA), four doses of each herbicide (0.5 D, 0.75 D, 1.0 D and 1.25 D, where D = recommended dose), plus an untreated control. The products were applied to alfalfa plants at the stage of 4 to 5 leaf pairs. In the second experiment, the effect of pre-emergent herbicides on early alfalfa development was observed through a completely randomized design with five replications in a 3 x 4 x 2 factorial scheme, with three herbicides (hexazinone, atrazine + simazine, S-metolachlor), four doses (0.5 D, 0.75 D, 1.0 D and 1.25 D), and two types of soil texture (loamy and clay soil), plus an untreated control. The third experiment evaluated the action of atrazine, 2,550 g ha -1 ; clomazone -600 g ha -1 ; diclosulam -25 g ha -1 ; diuron+hexazinone -936 + 264 g ha -1 and diuron+hexazinone +sulfometuron -1,386 + 391 + 33.35 g ha -1 on alfalfa sown at different times after herbicide application. The effects of the treatments on alfalfa were evaluated according to visual phytotoxicity symptoms, plant height, and biomass of roots and shoots. Among the herbicides applied at post-emergence, imazethapyr, clethodim, haloxyfop-p-methyl and MSMA were selective for alfalfa, while among those applied at pre-emergence, none were selective, regardless of soil texture. The results of the third experiment showed that the herbicides diclosulam, hexazinone + diuron and atrazine caused less toxicity in alfalfa plants.Keywords: phytotoxicity, Medicago sativa, residual period. (bentazon, chlorimuron-ethyl, fomesafen, fluazifop-p-butil, saflufenacil, imazethapyr, cletodim, nicosulfuron, imazaquim, haloxyfop-methyl e MSMA), quatro doses de cada herbicida (0,5D, 0,75D, 1,0D e 1,25D, sendo D = dose comercial) RESUMO -O objetivo desta pesquisa foi verificar a seletividade de herbicidas aplicados em pré e pós-emergência para a cultura da alfafa. Esta pesquisa foi composta por três experimentos distintos, realizados em casa de vegetação. O primeiro experimento foi conduzido em delineamento experimental inteiramente casualizado com três repetições, em esquema fatorial 11 x 4+1, sendo onze herbicidas

Selectivity of post-emergent herbicides for weed control in birdsfoot trefoil crops

“…In soybean crops, no negative effect of flumetsulam and chlorimuron-ethyl application was found on plant height (Osipe et al, 2014). Similar responses were observed when imazethapyr and chlorimuron-ethyl were applied to alfalfa crops (Silva et al, 2001;Silva et al, 2003;Hijano et al, 2013).…”

“…Species, such as soybean, that belong to the family of birdsfoot trefoil also exhibit selectivity of herbicides flumetsulam and chlorimuron-ethyl to the crop and low phytotoxicity 15 DAE (Osipe et al, 2014). In addition, similar phytotoxicity was caused by herbicides imazethapyr, chlorimuron-ethyl and imazamox (Silva et al, 2004) and imazethapyr (Hijano et al, 2013) to alfalfa crops.…”

The safener effect of chiral derivatives of 3-dichloroacetyl oxazolidine against haloxyfop-P-methyl-induced toxicity in maize

“…Haloxyfop-P-methyl controls weeds by competitive binding to acetyl-CoA-carboxylase (ACC), which is an important enzyme in the biosynthesis of fatty acids (Hijano et al, 2013). However, application of haloxyfop-P-methyl at recommended dose may cause injury to some soybean cultivars (Parsa et al, 2013).…”

Imazamox selectivity for alfalfa crop

“…U drugoj oceni, ni na jednom od lokaliteta, nisu bili vidljivi simptomi fitotoksičnosti na usevu lucerke. Dobijeni rezultati potvrđuju činjenicu da se neke biljne vrste mogu oporovati od stresa, u zavisnosti od stepena fitotoksičnosti, intenziteta oštećenja i faze razvoja useva (Hijano et al, 2013).…”

“…Utvrđeno je da niz faktora utiče na razvoj i kvalitet lucerke, a ključnu ulogu imaju korovi (Mseddi et al, 2017), prevashodno zbog sporijeg početnog rasta useva. Korovi koji se javljaju nakon setve mogu značajno uticati na rast i razvoj lucerke (Hijano et al, 2013), a kao rezultat njihove kompeticije za vodu, hranljive materije i svetlost, prinos i kvalitet sena mogu biti značajno smanjeni (Canevari, 2001;Canevari et al, 2007). Tako na primer, korovi u kišovitim godinama mogu smanjiti prinos lucerke i do 60%, što za posledicu ima i smanjenje prinosa suve biomase i do 75% (Rassini et al, 1995).…”