Initial tolerance of cowpea to herbicides applied in pre-emergence

Abstract

Weeds that are not well managed can cause losses of more than 90% in the final production of the crops, and for cowpea there is a certain difficulty to control them, since there are no herbicides registered for the crop. The objective of this study was to evaluate the initial tolerance of cowpea to herbicide application in pre-emergence of the crop. The experiment was conducted in a greenhouse, in a completely randomized design, with three replications. The treatments evaluated were sulfentrazone (200 g ha-1), S-metolachlor (768 g ha-1), [clomazone + carfentrazone] ([480 + 12] g ha-1), imazethapyr (50 g ha-1), flumioxazin (50 g ha-1), sulfentrazone + S-metolachlor (200 + 768 g ha-1) and one control. All herbicides were applied after sowing cowpea. Plant phytotoxication, plant count, plant height, dry shoot and root mass were evaluated. The mixture of sulfentrazone + S-metolachlor herbicides promoted irreversible crop damage. Cowpea does not tolerate flumioxazin or mixtures involving the use of this herbicide. It can be observed that the cowpea presented intermediate tolerance to the herbicides sulfentrazone and diclosulam. The herbicides S-metolachlor, imazethapyr and cloransulam presented potential use in pre-emergence applications of cowpea.