There is much debate about the use of wetting agents when applying herbicides, fungicides, and pesticides. Some say they are unnecessary, and others believe you can use detergents and save money. So let’s unravel the hearsay with some scientific facts.
What are detergents?
Detergents are a cleansing agent, usually consisting of salts of long-chain aliphatic bases or acids that exert cleansing or oil dissolving and antimicrobial effects through a surface.
Detergents are great for cleaning dishes and removing grease and grime. They are not designed to stick herbicides to plants or assist in forcing the herbicide into the plant so it can be translocated to the root system. The detergent’s mode of action is to dissolve grease and grime and can adversely impact the active ingredients mixed in spray solutions.
What are wetters?
A wetter or surfactant is a group of chemical substances that act as wetting agents to lower a liquid’s surface tension and allow for increased spreadability. Reducing the spray droplets’ surface tension allows the herbicide to penetrate the leaf surface more effectively, resulting in a better kill.
What is the main difference between detergent and wetting agents?
Detergents are surfactants; however, they are formulated to be used as a cleaning solution. Therefore, they do not force the chemical into the plant and will not benefit the herbicide to be more effective. Detergents look as though they are effective as they foam up and leave an oily residue on the plant’s surface, but that is the extent of it.
Wetting agents are chemical substances that have been produced specifically to increase the spreading and penetrating properties of a liquid by lowering the surface tension, that is, the tendency of its molecules to adhere to each other.
When used according to the direction of use, wetting agents or surfactants maximize spray application by wetting and sticking the herbicide to the plant by lowering the surface tension of the spray droplet. Some also assist in penetrating the plant by forcing the active ingredient deep inside the weed tissue, where it is translocated to the root system. This is what separates non-ionic wetting agents from simple washing detergent and improves the efficacy of your herbicide, creating a greater success rate in eradicating the weed.
A wetting agent or surfactant ‘wet’ the plant foliage rather than simply beading up and dripping off the plant’s surface, ensuring a better result from the herbicides and insecticides you use and spend your money. This is particularly important when plants have waxy or hairy foliage. Breaking down the surface tension of the spray droplet allows the chemical to penetrate the foliage and kill the weed or pest.
Eradicating weeds is labor-intensive and can be expensive, so you want to ensure you do it right the first time.
What is the best wetting agent to use?
There are several wetting agents on the market for crops and gardens.
Non-ionic wetting agents improve spray coverage when using agricultural chemicals. These wetters should be used where the addition of a surfactant is required or recommended on the label of the chemical.
Specialty surfactants can also be used in agricultural applications. These surfactants acidify and penetrate foliage and can be used where the addition of a wetter/spreader or self-emulsifying oil is required or recommended on the agricultural chemical label.
Other surfactants can be a spray additive when used with fungicides, insecticides, and weed killers. These surfactants increase the activity of pesticides and increase the spray droplet coverage for waxy leafed plants, which are typically hard to wet.