Surfactants
are chemicals that change the physical properties of liquid surfaces. Although
soap and household detergents are surfactants, they are not as effective as the
commercial agricultural ones. When added
to herbicides, surfactants will:
- Enhance the spread of the spray droplets on the leaf surface. This increases the effectiveness of the herbicide.
- Enable the herbicide to be more rain resistant.
- Reduce the rate of drying of the spray solution.
- Aid in the suspension of insoluble pesticides like powders in water.
- Reduce the proportion of very fine droplets, thus reducing spray drift.
Gardeners
should always apply herbicides (any pesticide for that matter) at the
recommended label rate. Overdosing is a common error - thinking that a higher
concentration will result in a better or quicker kill. This, however, will result in unnecessary
expense, an unnecessary release of herbicide into the environment, and,
ironically, poor weed control. With systemic foliar herbicides, an effective
weed kill depends on the herbicide being trans-located (moved) from the leaves
to the roots. Too high a rate will close down the system and the necessary
amount of herbicide will not reach the root system.
