Adjuvants are any substance you add to a spray mixture to enhance efficacy or efficiency. They modify the physical or chemical characteristics of other products, so they can do their jobs better. Not all adjuvants work with every product, however. You need to know which ones to use with which products. This is where we remind you how important it is always to read the labels, so you know which adjuvants will work with the product you have.
Below is a high-level overview of a recent conversation we had with leading agronomist and pest control advisor, Paul Crout, on episode 71 of the Vineyard Underground Podcast.
Two Main Categories of Adjuvants
- Activators or Surfactants
Surfactant is a word derived from “surface active agent.” They are designed to enhance the physical characteristics of a spray solution and maximize coverage. For example, if you mixed sulfur and water and sprayed it on leaves, it would bead up and have “surface tension.” If you add a surfactant, it would break up the surface tension and allow the sulfur to spread over a larger amount of leaf area.
Spreader stickers are a type of surfactant that creates films or a chemical process that adheres the spray to the outside of the leaf. They can be latex-based or oil-based, just like paint.
Penetrants are oil-based, but you have to be careful because they can penetrate too well and burn the leaves if used at too high of a rate or improperly tank mixed with other products.
- Utility or Special Purpose
These adjuvants are used on everything else, like water conditioners, and are also used to break the surface tension of the water solutions. They can be used to neutralize hard water, as indicator dyes, as drip control agents, etc.
Three Main Categories For Canopy Sprays
- Non-ionic Surfactants
The word “ionic” indicates a positive or negative charge, or if the chemical is neutral. Non-ionic is somewhat of an umbrella and can include organosilicone and methylated seed oils in this category. You can consider it to be a jack of all trades. If you are a new grower or if you have never used an adjuvant before, a non-ionic one would be a good start because they are generally safe and can do a little bit of everything. The non-ionic surfactants could be considered the “gateway” to spray adjuvant use!
- Organosilicone
Being under the non-ionic umbrella, organosilicone is considered to be safe. It’s also a super spreader, meaning it works almost two times better than regular non-ionic surfactants. They break surface tension more powerfully and allow the product to soak into the leaf more effectively, and can often be used at lower rates than non-ionic surfactants.
- Methylated Seed Oil
Methylated seed oils (MSOs) are made from canola, soybean, corn, or any vegetable or plant-based oils. They are then refined and methylated, which creates the solvency rating of the oil. Designed to drive a product into the leaf by softening the cuticle of the leaf, they are not as safe to use as the other non-ionic surfactants. You do not want to overapply MSOs because they could burn the leaves and ruin your production. You should always check the label of any product you spray to be sure it is compatible with oils or MSOs. The label is the law!If you want to learn more about demystifying spray adjuvants, check out https://www.vineyardundergroundpodcast.com/vu071.
