Weed Control J 2021; 20: e202100736

Research Article

Herbicides to ruzigrass suppression in intercropping with corn

DOI: 10.7824/wcj.2021;20:00736

Abstract

Background

The corn intercropping with Brachiaria ruziziensis has rapidly raised in South and Center-West of Brazil. However, the uncertainty about forage interference on corn yield has led growers to use herbicides to suppress ruzigrass.

Objective

Our objective was to evaluate sub-doses herbicides applied in different stages of ruzigrass to suppress the growth in an intercropping system with corn.

Methods

A greenhouse experiment was carried out to evaluate the forage intoxication by herbicides to select the best treatments. Subsequently, a field experiment was carried out to investigate corn yield and B. ruziziensis suppression, using sub-dose herbicides in two stages of application. The experiment were arranged in a 9×2+3 factorial scheme, carried out in a randomized block design with eight repetitions. The first factor was composed by herbicide treatments, the second factor was composed of two phenological stages of ruzigrass and their effects were compared with three additional treatments.

Results

Herbicides applied on ruzigrass plants with more than 3-tillers showed lower injury levels than 1-tiller stage. In the field, forage intoxication ranged from 2.5 to 54%, with higher suppression levels to nicosulfuron when compared to mesotrione.

Conclusions

The application of mesotrione (48 or 60 g ha-1) and atrazine (1200 g ha-1) at 1-3 tiller stage; and mesotrione (60 g ha-1), mesotrione+atrazine (60+1200 g ha-1) and atrazine (1200 g ha-1) applied on more than 3-tillers are efficient treatments.