Dose-response curve to soil applied herbicides and susceptibility evaluation of different amaranthus species using model identity

Abstract

-Greenhouse studies were conducted in [2008][2009] with the objective of adjusting dose-response curves of the main soil-applied herbicides currently used in cotton for the control of Amaranthus viridis, A. hybridus, A. spinosus, A. lividus, as well as comparing susceptibility among different species, using the identity test models. Thirty six individual experiments were simultaneously carried out in greenhouse, in a sandy clay loam soil (21% clay, 2.36% OM) combining increasing doses of the herbicides alachlor, clomazone, diuron, oxyfluorfen, pendimethalin, prometryn, S-metolachlor, and trifluralin applied to each species. Dose-response curves were adjusted for visual weed control at 28 days after herbicide application and doses required for 80% (C 80 ) and 95% (C 95 ) control were calculated. All herbicides, except clomazone and trifluralin, provided efficient control of most Amaranthus species, but substantial differences in susceptibility to herbicides were found. In general, A. lividus was the least sensitive species, whereas A. spinosus demonstrated the highest sensitivity to herbicides. Alachlor, diuron, oxyfluorfen, pendimethalin, S-metolachlor, and prometryn are efficient alternatives to control Amaranthus spp. in a range of doses that are currently lower than those recommended to cotton.Keywords: cotton, dose-response curve, pigweed, tolerance. RESUMO -Em

Duration of Soil Activity of Foramsulfuron Plus Thiencarbazone-methyl Applied to Weed Species Typical of Sugar Beet Cultivation

“…High herbicide dosages are often necessary to achieve adequate weed control (Talgre et al 2008). In the present study, weed control significantly increased with increasing herbicide dosage (Figure 3b), as also shown in earlier studies for both PRE and POST application of herbicides (Raimondi et al 2015). This is mainly due to a higher amount of ai in the plant tissue per unit weight at higher dosages (Schuster et al 2007).…”

Glyphosate Resistance in Amaranthus viridis in Brazilian Citrus Orchards

“…Slender amaranth (Amaranthus viridis L.) is widely spread over tropical and subtropical regions in more than 80 countries [17]. These species, as well as other Amaranthus species, are the most abundant weeds in the Brazilian south and center-west regions [18]. In 2010, this weed was reported with multiple resistance to the acetolactate synthase (ALS) and photosystem II inhibiting herbicides in cotton in the states of Bahia and Mato Grosso, Brazil [19], and in 2015, Amaranthus palmeri was found with resistance to glyphosate and ALS-inhibiting herbicides in soybean in the state of Mato Grosso, Brazil [20].…”