Herbicide selectivity and weed control in cowpea

Abstract

Weeds negatively affect cowpea plants, causing reduced growth, delayed development and yield loss. The aim of this study was to assay selectivity and effectiveness of weed control herbicides in cowpea cropping field conditions. For selectivity evaluation, the herbicide S-metolachlor, was used pre-emergence (PRE), and carfentrazone-ethyl, clethodim, fenoxaprop-p-ethyl, fluazifop-p-butyl and quizalofop-p-ethyl post-emergence (POST). In effectiveness evaluation, S-metolachlor (PRE), and carfentrazone-ethyl (POST), S-metolachlor in PRE and fluazifop-p-butyl (POST), clethodim, carfentrazone-ethyl and clethodim, fenoxapropp-
 ethyl, carfentrazone-ethyl and fenoxaprop-p-ethyl, fluazifop-p-butyl, carfentrazone-ethyl and fluazifop-pbutyl, quizalofop-p-ethyl and carfentrazone-ethyl and quizalofop-p-ethyl (POST). Two controls were included, one with weeding at 15 and 35 days after sowing (DAS) and the other without weed control. Carfentrazone-ethyl caused mild phytotoxicity in plants seven days after application, but did not reduce yield (2337 kg ha-1). The levels of weed control and productivity obtained with S-metolachlor alone or in association with carfentrazoneethyl or fluazifop-p-butyl, associated or not with carfentrazone-ethyl, were similar to those obtained with weeds. Spraying with carfentrazone-ethyl alone resulted in low control effectiveness and reduced yield (1511 kg ha-1). Weed interference during the crop cycle reduced yield by 77% (531 kg ha-1). The selectivity and effectiveness obtained with the herbicides should be considered as an agronomic and economically-viable.

Weed infestations in soybean grown in succession to cropping systems with sorghum and cover plants

“…However, when there was an intercropping, like sorghum with Congo grass, a low similarity of 0.45 with all other systems occurred, probably due to the increasing in the amount of straw in the soil surface. According to Fontes et al (2019), the number of germinated seeds on the soil surface reduces as the amount of straw increases.…”

“…These species can be cultivated before the main crop -soybean, for instance -during the short-season of the Cerrado region. Systems like these may have potential to keep weed population below the economic damage level because of the control during the grasses development, characterizing a strategy of reducing but not eradicating weeds (Noce et al, 2008;Fontes et al, 2019). Correia et al (2011) described the effects of soil coverage by palisade grass on weed control, which contributes both to the reduction of chemical application and to the control of herbicide-resistant species, such as Digitaria spp.…”