What is the impact of low relative humidity on herbicide absorption?

The impact of low relative humidity on herbicide absorption primarily relates to its effect on the plant's cuticle, the outer protective layer that regulates water loss and gas exchange. When relative humidity is low, plants often experience increased transpiration rates, which can lead to a thickening of the cuticle as the plant attempts to minimize water loss. This thickened cuticle can reduce permeability, making it more difficult for herbicides to penetrate the leaf surface.

Consequently, herbicides that rely on cuticular absorption may face challenges in entering the plant, as the protective nature of the cuticle is enhanced under dry conditions. This means that herbicide efficacy can be compromised when relative humidity is low, as the protective barrier becomes less permeable. In this context, understanding the relationship between humidity and cuticle properties is essential for effective herbicide application and management in Integrated Pest Management strategies.