Herbicides weed management in changing environmental conditions

Elevate CO2 levels in the atmosphere might have prominent effects on weed phenology, consequently changing herbicide performance on weeds. Increased atmospheric CO2 concentration increase leaf thickness and reduce stomatal number and conductance potentially reducing the absorption of POST–emergence applied herbicides. From the other side, higher temperature stimulates stomata conductance, reduce the viscosity of epicuticle waxes, thus increasing the penetration and diffusion of herbicides as a result of changes in the composition and the permeability of the cuticle. However, in some circumstances higher temperatures might cause hastened metabolism, which consequently decreases herbicide activity on target plants. In conditions of higher RH, cuticle hydration and stomatal conductance increases, consequently increases the permeability and translocation particularly of hydrophilic herbicides into the leaves. Similar, under higher irradiance, stomata stay open, photosynthetic rate increases consequently increasing absorption, penetration and subsequent phloem translocation of POST–em systemic herbicides in weed tissue. Drought might cause increased cuticle thickness and increased leaf pubescence, with consequent reductions in herbicide absorption into the leaves. Rainfall after POST–emergence herbicides application might reduce their efficiency through washing out. Increased frequency and intensity of precipitation will have a negative effect on absorption, translocation, and activity of PRE–emergence herbicides.