Trials for post-emergence weed control in faba beans

Abstract

Faba beans (Vicia faba) enjoy rising popularity. Since the herbicide Basagran (Bentazon) is no longer available, weed control is only possible as pre-emergence treatments. This is especially a problem for farms with conservation tillage, where a layer of mulch can possibly impede the effectiveness of soil herbicides. On all farms a subsequent treatment could be desirable, if spring drought makes the herbicide treatments less effective.
To answer this questions the University of Applied Science in Soest / Germany carried out a pot trial under semi field conditions in spring 2016. In this trial twelve herbicides licensed in other crops were tested for their compatibility to faba beans in an early post-emergence stage. Half of the used herbicides resulted in light to distinct damage on the horse beans.
In the following year 2017 the as promising identified herbicides Betanal maxxPro (Phenmedipham + Desmedipham + Ethofumesat + Lenacil) and Clearfield-Clentiga (Imazamox + Quinmerac) were transferred to field trials in two locations in the area of Soest, where they were tested for their compatibility and efficacy. Visible phytotoxic symptoms in form of depression in growing and slight necrosis were found on the variants including Betanal maxxPro in both locations, but the symptoms were outgrown fast. The efficacy of the postemergence herbicides was very different in both locations and did not reach the dependable efficacy of the pre-emergence products.