Conyza spp. control and selectivity of 2,4D in ENLIST® soybean ¹

Controle de Conyza spp. e seletividade do 2,4-D em soja ENLIST®

ABSTRACT

The introduction of 2,4-D-tolerant soybeans (ENLIST^®) offers a new potential for herbicide application. Therefore, the present study aimed to (a) evaluate the effect of combinations of post-emergent herbicides on the control of Conyza spp. and (b) assess the selectivity of the post-emergent herbicide association in soybeans, ensuring effective application without compromising the health of the crop. A field experiment with 2,4-D-tolerant soybeans utilized a randomized complete block design with 14 treatments across four replications. Treatments included various combinations of 2,4-D with glyphosate, chlorimuron-ethyl, cloransulam-methyl, imazethapyr, bentazon, and imazamox. These were applied either as a single treatment or sequentially 15 days after treatment (DAT) using glufosinate-ammonium alongside two controls without herbicide application. The results showed less than 15% control across all treatments. At 21 DAT, only the treatments applied sequentially showed significant control, with effectiveness exceeding 80% against Conyza spp. In contrast, the single applications of the herbicide combinations with 2,4-D were ineffective for post-emergence control of Conyza spp.

Key words:
2,4-D-tolerant soybeans; horseweed; post-emergent herbicide combinations

HIGHLIGHTS:

Sequential glufosinate-ammonium applications enhance Conyza spp. control in dense infestations.

Sequential applications boost control, regardless of herbicide combinations with 2,4-D and glyphosate.

The sequential application of glufosinate-ammonium results in high soybean grain yields.