Understanding Mechanisms of Herbicide Selectivity in Agro- Ecosystems: A Review

Weeds cause yield losses in desired crops through competition for sunlight, water, space, and nutrients. It is important to manage weeds in crop fields and aqua bodies using various management strategies. One of the most effective and efficient ways of managing weeds is through the use of herbicides. However, there is a need to understand the effects of these herbicides on the desired plants and/or the environment. Herbicide selectivity allows the application of herbicides in a field with both the desired crop and weeds. Herbicide selectivity is therefore described as, an application treatment at a given dosage that is toxic to some plant species but does not damage another species. However, many herbicides can be toxic at high dose rates even when applied to tolerant crops. There are several mechanisms of herbicide selectivity which are grouped into physiological and physical. Physical herbicide selectivity occurs when physical factors such as time, the position of application, plant morphological structure, and environment aid in selectivity. Physiological selectivity occurs when the plant species affect herbicide retention, penetration, movement, and detoxification. Herbicide selectivity is known to be a major cause of difficulties in controlling weeds. As a result, there is a need to understand how the environment, herbicides, and plants contribute to selectivity. This paper, therefore, provides insights into herbicide selectivity and how plants escape herbicide injury which enables species diversity.