Estimating Yield Losses in Soybean Due to Sourgrass Interference

Abstract

Efficient management of sourgrass is one of the main challenges faced by Brazilian soybean farmers. Biological and ecological characteristics of this weed, as well as wide distribution of glyphosate-resistant biotypes, make it difficult to control this species. The objective of this work was to estimate interference of sourgrass in soybean yield. Seven experiments were conducted during three consecutive years (2012/2013, 2013/2014 and 2015/2016 cropping seasons); six of them were on-farm trials where sourgrass infestation was mainly originated from clump regrowth, while infestation originated from seeds in one trial. Data from all sites and experiments were submitted to a combined analysis, according to the study factors and variables, to determine the greatest number of information points for the variable under each circumstance. To each data set, a 1st degree polynomial regression was fit, with a 95% confidence interval. The degree of sourgrass interference varies according to plant origin (seed or clump regrowth) but, in both cases, yield losses are directly correlated with sourgrass densities, aboveground dry mass accumulation and soil coverage. Plants coming from clumps tend to cause higher yield losses than those originated from seeds. These data highlight the importance of performing proper management of sourgrass, especially in its initial stages of development, in view of the high level of losses that perennial plants can cause to crops.

Viabilidade Técnica E Econômica Da Adição De Inibidores Da Accase E Da Als Ao Glyphosate No Controle De Plantas Daninhas E No Rendimento De Grãos Da Soja

“…O capim-amargoso apresenta grande efeito sobre a o rendimento de grãos da soja, mesmo em baixas densidades. Uma única planta por m 2 pode reduzir o rendimento de grãos de soja em 500 a 1.400 kg ha -1 (GAZZIERO et al, 2019). Outros trabalhos indicam que essa planta daninha, na densidade de 1 a 3 plantas por m 2 , pode causar redução de 23,5% no rendimento de grãos de soja, e de 44,5% quando a densidade for de 4 a 8 plantas de capim-amargoso por m 2 (GAZZIERO et al, 2012).…”

Weed control and soybean agronomic performance in response to application of sulfentrazone + diuron in pre-emergence

“…The problem is aggravated when weeds are resistant to herbicides (ADEGAS et al, 2017). For example, one plant per m -2 of sourgrass (Digitaria insularis) resistant to glyphosate results in a reduction of 500 to 1,400 kg ha -1 in soybean grain yield (GAZZIERO et al, 2019), and its control cost is, on average, 165% higher compared to that of a susceptible infestation (ADEGAS et al, 2017). There are currently 52 cases of weed resistance to herbicides in Brazil (HEAP, 2021), and measures to manage these populations and prevent the emergence of new cases are essential.…”

Sensitivity of Digitaria insularis to herbicides in agricultural areas, in the Brazilian Cerrado biome

“…The infestation of resistant biotypes of D. insularis to glyphosate has increased in agricultural areas in the Brazilian Cerrado biome (Lucio et al, 2019). This can result in increases of the production costs because of the need to adopt other management strategies, or in the yield reduction of the crop of economic interest due to competition with weeds that are not controlled (Gazziero et al, 2019). According to Adegas et al (2018), the cost of weed management in soybean crop areas with glyphosate-resistant D. insularis may increase from 165 to 290%.…”