Pre-emergence control and interference of voluntary maize plants on a soybean crop in Brazilian Cerrado

Abstract

The succession of soybean/maize has been largely adopted. Storm damage and crop problems can lead to grain loss, generating maize ear fragments or even whole ears that remain in the soil and still display germination viability, resulting in the occurrence of volunteer plants. In this context, the present study aimed to evaluate the interference of voluntary maize plants on soybean and investigate the susceptibility of maize hybrids to pre-emergence herbicides. In the first step, an experiment was performed evaluating the influence of voluntary maize plant density and spatial distribution on soybean. The experiment was performed in a randomized completely block design (RCBD) with four replications, with treatments disposed in factorial arrangement (2 x 4) + 1. The first factor corresponded to the spatial distribution of maize plants: row or in between soybean rows; while the second factor adopted four infestation densities of maize plants m-2: 4, 8, 12, and 16. The additional treatment consisted of a control without maize plants. For the second step, an experiment was conducted in two locations aiming to determine the efficacy of pre-emergence herbicides in the control of voluntary maize. Both experiments were installed in RCBD in a split-plot scheme with four replications. Fomesafen, lactofen, sulfentrazone, chlorimuron-ethyl, diclosulam, flumetsulam, imazethapyr, clomazone, metribuzin, [sulfentrazone + diuron], [imazethapyr + flumioxazin], and a control without herbicide application were evaluated in the main plot. In each subplot, the maize hybrids DKB310 PRO3™ and DKB390 PRO3™ were evaluated. No influence on the position of voluntary maize on the soybean yield was observed. The presence of the maize population led to a progressive decrease in soybean yield, ranging up to 86%, at 16 plants m-2. DKB390 displayed a stand reduction of 82.88% after the use of diclosulam. Diclosulam led to better results regarding maize plant decreases for both hybrids.

Weed Competition on Soybean Varieties from Different Relative Maturity Groups

“…Thus, it can be seen that weed control in the initial period of soybean development resulted in a reduction of approximately 43% in the number of weeds recorded at harvest. This fact demonstrates the importance of using pre-emergence herbicides to reduce the number of individuals competing with the crop [26,27]. Furthermore, these weeds were suppressed by soybean, with very small size, showing a low competitive capacity with the crop.…”

Influence of Chemical Control on the Floristic Composition of Weeds in the Initial and Pre-Harvest Development Stages of the Sunflower Crop

“…Sunflower was grown in succession to soybean, which favored the establishment of volunteer soybean plants from grain lost during harvest [28]. Volunteer plants, which generally have traits of resistance to herbicides such as glyphosate, can cause losses of up to 80% of productivity in the succession crop [29], which, in this case, is sunflowers. According to the study, herbicides used in pre-and post-emergence with modes of action different from glyphosate showed good control of volunteer soybeans in experimental areas cultivated with sunflower [30].…”

Implementation and Use of Green Manures for Weed Suppression in Sequential Maize Cropping

“…Te weeds located within the frame were collected and weighed using scales with 0.005 g precision [29]. Weed suppression (Mg•ha −1 ): the control treatment (T11: conventional system) [30] was used as a reference for the determination of the green mass of weeds and weed suppression. Formula (1) was used to obtain the values of weed reduction at 60 and 90 days after the planting of green manures.…”