Competition periods of crabgrass with rice and soybean crops

Abstract

-Determining the periods of weed competition with crops helps the producer to choose the most appropriate time to use weed control practices. This strategy allows for the reduction of the number of herbicide applications, reducing costs and the environmental impact of pesticides. The objectives were to determine the period before the interference (PBI) of crabgrass (Digitaria ciliaris) competing with flooded rice, the critical period of interference prevention (CPIP) of crabgrass with soybean and the effects of competition on the grains yield and their components. Experiments were conducted with the coexistence of BRS Querência rice cultivar with crabgrass, for periods of 0, 7, 14, 21, 28, 35, and 110 days after emergency (DAE) and Fundacep 53RR soybean cultivar, whose periods of coexistence and control of crabgrass were 0, 7, 14, 21, 28, 35, and 156 DAE. Rice can grow with crabgrass infestation until 18 DAE, while soybean should remain free from the presence of crabgrass in the period between 23 and 50 DAE. The grain yield and its components, in the crops studied, are affected when grown with crabgrass. BRS Querência, com milhã, por períodos iniciais crescentes de 0, 7, 14, 21, 28, 35 Keywords: Digitaria ciliaris, Oryza sativa, Glycine max, interference RESUMO -A determinação dos períodos de competição das plantas daninhas com as culturas auxilia o produtor na escolha do momento mais adequado para utilizar medidas de manejo. Essa estratégia possibilita reduzir o número de aplicações de herbicidas, com consequente redução de custo e menor impacto dos agrotóxicos ao ambiente. Assim, os objetivos deste trabalho foram determinar o período anterior à interferência (PAI) de milhã (Digitaria ciliaris) na cultura do arroz irrigado, o período crítico de prevenção à interferência (PCPI) de milhã na cultura da soja e os efeitos da competição na produtividade de grãos e seus componentes. Para isso, foram conduzidos experimentos de convivência de arroz irrigado, cultivar

Interference Periods in Soybean Crop as Affected by Emergence Times of Weeds

“…Among biotic factors, competition with weeds stands out, since they can cause losses of up to 80% in yield (Silva et al, 2009a), considerably increasing production costs. Such losses can be influenced by weeds species and population in the area, their time of emergence and the phenological development stage of the species (Agostinetto et al, 2014), which provide different degrees of competition.…”

“…Competition of weeds with crops can generate irreversible losses, with no recovery of development or yield after withdrawal of stress caused by their presence (Agostinetto et al, 2014). Such effects can be expressed in morphophysiological alterations in plants, which compromise the development of reproductive structures, reflecting in reduction of grain production (Adelusi et al, 2006) due to being hosts of insects, pathogens and nematodes (Vasconcelos et al, 2012), hindering operation of crop practices and harvesting and reducing sugar cane yield (Millar et al, 2011).…”

“…Thus, the longer this period in which the community is competing for a given resource, the greater the damage to yield. It is known that competition established mainly in the early stages of the cycle causes significant losses in yield (Agostinetto et al, 2014) and weed-free crops should be established to avoid such losses.…”

“…There are several competition period studies for soybean cultivation (Silva et al, 2009b;Tavares et al, 2012;Agostinetto et al, 2014) but none was performed in order to establish the periods according to weed emergence flow. Studies related to germination beginning and the emergence flow of weeds allow the development of management strategies that provide greater competitive ability to the crop, which can reduce the number of herbicide applications, improve control efficiency and also reduce possible environmental contaminations and/or the emergence of resistant weeds.…”

A Multy-Year Study Reveals the Importance of Residual Herbicides on Weed Control in Glyphosate-Resistant Soybean

“…The crabgrass (Digitaria ciliaris) is an annual narrow-leaf plant with decumbent development that reproduces by seeds, being very competitive with the agricultural crops (Kissmann and Groth, 1997). Crops such as flooded rice and soybeans showed a decrease in yield in weed-crop competition needing to remain free of this weed between 23 and 50 days after emergence (Agostinetto et al, 2014). Normally, there is success in controlling crabgrass with glyphosate application.…”