Soybean yield loss and economic thresholds due to glyphosate resistant hairy fleabane interference

Abstract

The interference of glyphosate resistant hairy fleabane (Conyza bonariensis) has caused yield losses in soybean crop. Knowledge of the economic threshold is an important aspect for the economic management of resistant weeds. Because of it, the interference of the glyphosate resistant hairy fleabane density on the soybean yield loss was evaluated, as well as to estimate the economic threshold. Two experiments were conducted to verify the effect of different weed densities on the yield of two soybean cultivars (BRS Estância and BMX Turbo). Weed density ranged from 0 to 124 plants m-2. The yield of the BRS Estância decreased by 1.4% to the increase of one single plant, while for the BMX Turbo the loss was 25.9%. Soybean yield and economic threshold were lower for the BMX Turbo cultivar compared to the cultivar BRS Estância, which can be attributed to the genotype, competitive ability, weed development stage and/or environment. Increases in crop yield expectation, soybean price and herbicide efficiency reduce the economic threshold, indicating that the adoption of control measures should be taken when the weed density is low. Due to the high cost of hairy fleabane control, it is only feasible at high densities.

Weed Interference and Growth Performances in Soybean (Glycine max (L.) Merr.), as affected by Weed Density and Types of Weed

“…In the same way, Agostinetto et al (2017) who reported that the soybean planting interfered with hairy fleabane infestation showed the loss of growth and yield against soybean is more harmful than the soybean planting alone (no weed interference).…”

“…The accumulation of the weed density in crop planting showed the growth retardation as well as the minimization of yield is more harmful than the reduction of the weed density (Agostinetto et al, 2017). For the soybean planting and economic field crops interfered with weeds competition showed the injury of some characters of crops and soybean planting included reduction of the growth characters (Keramati et al, 2008), damage of the yield components (Du et al, 2019) and decrease of the yields (Korres et al, 2020).…”

Monitoring Glyphosate- and Chlorimuron- resistant Conyza spp. Populations in Brazil

“…According to recent estimates, more than 10 million ha cultivated with soybean are currently infested with herbicide resistant Conyza populations in Brazil (Adegas et al 2017). Considering that Conyza interference can cause up to 91% yield loss (Agostinetto et al 2017), effective management strategies must be developed.…”

Conyza bonariensis growth and development according to thermal time accumulation and photoperiod

“…Hairy fleabane [Conyza bonariensis (L.) Cronquist] is a weed of the Asteraceae family whose main characteristics are high competitivity and prolificacy, producing more than 800 thousand seed per plant (Kaspary et al, 2017). Worldwide, hairy fleabane is one of the main weeds in wheat, soybean, and maize cultivations, causing significant drops of grain yield (Vargas et al, 2007;Agostinetto et al, 2017). Furthermore, there are recognized cases of this species resistance to several mechanisms of herbicidal action, the main of which is the resistance to glyphosate (Heap, 2019).…”