Herbicide. Not all herbicides behave similarly in or on the plant.
Differences in the herbicide’s oil or water solubility influence absorption. Some
surfactants work best with a certain type of herbicide and not others. Surfactant
solubility should complement the solubility characteristics of the herbicide
selected. That is, both should be oil-soluble or both water-soluble.
Weed species. In most situations, the weed species will be the factor
which determines the herbicide and formulation selected. However, just as
herbicides should be carefully evaluated for a particular use, surfactants perform
differently based on the type of plant to be controlled. These differences are
based largely on differences in wax content and composition, leaf arrangement
and architecture, and plant hairs.
Environmental conditions. Also consider the environmental conditions
when selecting a surfactant. Thin, relatively permeable cuticles are favored by
high humidity and high moisture conditions. Under low humidity conditions,
plant cuticles are generally thicker and harder to penetrate. During such
conditions, crop oil concentrates and esterified seed oils can pass through the
waxy cuticles better than can nonionic surfactants.