Weed management with pre-emergent herbicides in soybean crops
Helis Marina Salomão1, Michelangelo Muzell Trezzi1, Matheus Viecelli2, Fortunato De Bortoli Pagnoncelli Junior2, Felipe Patel2, Leticia Damo3 and Gilvane Frizzon2
1Federal University of Technology, Pato Branco, PR, Brazil.
2Independent Agronomist, Brazil.
3Federal University of Viçosa, Viçosa, MG, Brazil.
The use of pre-emergent herbicides in soybean crops is fundamental, among other reasons, to maintain a clean crop in the initial stages, alter mechanisms, and consequently manage weed resistance. However, there is a considerable demand for information about the efficiency and selectivity of systems with residual herbicides applied in different modalities. This study evaluated the efficiency and selectivity of pre-emergent herbicides doses applied singly or mixed in a tank on soybean crops. The experiment was installed in randomized block design with 21 treatments and four repetitions. The treatments were composed of weeded and unweeded witnesses and pre-emergent application of isolated S-metolachlor or the herbicides diclosulam, flumioxazin, and sulfentrazone isolated or together with S-metolachlor in different doses with the addition of post-emergent S-metolachlor (soybean stage V2). Associations of residuals herbicides applied in pre-emergence or sequential mode increased the control levels of mono and dicotyledonous weeds. The treatments, including single or associated diclosulam and the systems with S-metolachlor sequentially, caused the most significant toxicity (up to 17%) for soybeans. High doses of S-metolachlor (2592.0 g ha-1), diclosulam (33.6 g ha-1), and the associations of S-metolachlor + diclosulam, S-metolachlor + flumioxazin, and S-metolachlor + diclosulam with sequential S-metolachlor should be avoided to obtain higher levels of soybean yield. The use of pre-emergent herbicides demonstrated to be an efficient and viable option to control weeds in soybean crops.
1. The association of residual herbicides generally increases the control levels of mixed natural infestations of mono and dicotyledons weeds.
2. It is possible to associate the grain yield of a soybean crop with the control efficiency of weed species and the toxicity of herbicides in the crop.