Floristic composition of weeds in a dystrophic Red-Yellow Argisol under the cultivation of cowpea, cv. BRS Novaera

Abstract

Among the several factors that negatively influence cowpea culture, weeds have been responsible for the reduction of growth, development and productive performance of the crop, making it necessary to establish management strategies based on phytosociological studies of weed species in growing areas. Therefore, the objective of this research was to evaluate the floristic composition of weeds, aiming to identify the main species and their dynamics, and to consider their distribution in time and space as pertaining to the cultivation of a modern variety of cowpea, cv. BRS Novaera, in dystrophic Red-Yellow Argisol, in the Midnorth region of the state of Piauí, Brazil. The phytosociological survey of weeds was carried out in three sessions: the first one was immediately before the area was desiccated with glyphosate (15 days before sowing the cowpea), and the others were at 20 and 40 days after sowing (DAS). Following the quantification of species and number of individuals, the following phytosociological parameters were calculated: frequency and relative frequency; density and relative density; abundance and relative abundance; and importance value index. It was concluded that there were few changes in the floristic composition of the weed community according to the epoch of the phytosociological surveys. The main weed plants at 20 DAS of cowpea (vegetative phase) were Chamaesyce hirta, Digitaria insularis, Alternanthera tenella, Cleome affinis, Mollugo verticillata and Portulaca oleracea. At 40 days (reproductive phase), the weed species with a large establishment and acting as potential competitors with cv. BRS Novaera cowpea were Digitaria insularis, Chamaesyce hirta and Mollugo verticillata.

Post-emergence herbicidal activity of nanoatrazine against Alternanthera tenella Colla plants compared to other weed species

“…This weed species has significant importance in agricultural areas with the cultivation of maize (one of the cultures for which atrazine is recommended) and cowpea (Alcântara Neto et al, 2019;D'Amico-Damião et al, 2020). For the post-emergence management of A. tenella, the application of triazine herbicides is recommended at early stages, when the plants show between two and four leaves (Adapar, 2022).…”

Control of Digitaria insularis (L.) Fedde in eucalyptus forests: shading increases sensitivity to glyphosate applied alone and in a mixture with carfentrazone-ethyl

“…Among them is Digitaria insularis [7], a perennial grass that is di cult to control, with biotypes resistant to glyphosate [8-10] and cross-resistance to ACCase-inhibiting herbicides [11]. D. insularis is also considered a weed in corn [12], soybean [13], cowpea [14], coffee [15], pastures [16] and in urban areas [9], which reinforces the species importance.…”