Tractor with sprayer
'Adjuvants' Improve Pesticide Efficacy
Spraying pesticides is a regular part of business for most growers, but ensuring the greatest efficacy and value comes with the challenge of balancing application methods with coverage. Dale Ziprick of United Agri Products Canada presented findings of how adjuvants can improve pesticide performance and cost efficiency at a presentation earlier this year.
“An adjuvant is any compound added to a pesticide formula or tank mix,” Ziprick explained.
Adjuvants are a broad range of products designed to improve spray application but have no biologically active ingredients. Their benefit is solely in their ability to bypass the physical and chemical processes that can negatively influence the action of pesticides.
Among adjuvants are four categories: Activators (designed to enhance pesticide performance usually by increasing absorption); Spray modifiers (designed to affect the physical properties of spray solutions); Utility modifiers (designed to make handling and application easier); And utility products like foam markers and tank cleaners. Of the four, surfactants fall into the activator category and as such have a Pesticide Control Product Act number. There is a wealth of information presented on a surfactant label such as type of formulation, mixability, restrictions and more.
“The message here is to read your labels,” noted Ziprick. “There are risks associated with adjuvants.”
Surfactants get their name from Surface Active Agents, which describes what they do. These adjuvants improve the contact made between droplets and foliage by allowing for a more uniform application, increasing the longevity of a product on the plant surfaces, increasing penetration through foliage structures, preventing crystallization of spray and increasing the water retention of droplets. Surfactants may be non ionic (“spreader” formulation including alcohol ethoxylate with the greatest degree of compatibility among pesticides), crop oil (petroleum-based oil mixed with emulsifier to allow oil to mix with water) and methylated seed oils (vegetable oil combined with emulsifier for solvency and compatibility with water for better leaf cuticle penetration).
It sounds like a lot of science, which of course it is, but ultimately, it’s about creating a better, more uniform pesticide solution and more penetration without applying larger amounts.
Surfactants are capable of creating more penetration than pesticides alone because of the ability to take droplets from the beading type seen on a freshly washed car to a flat spreadable surface. Size of these droplets can be positively influenced by surfactants as well. Growers know to adjust sprayer pressure, nozzle settings and operation procedures based on weather and other factors depending upon the best application droplet size of the pesticide. Different surfactants will allow for an increase in droplets that are driftable fines up to too large sized, allowing growers to choose the surfactant they need to further adjust the natural droplet size of the pesticide chosen.
Water, which is almost always the first part of the mixture, must be considered in the equation as well because pH, water hardness and other properties can impact pesticide performance. Adjuvants create chemical reactions to reduce or eliminate the negative impacts associated with water that may not be ideal for the pesticide.
Adjusting water hardness must be done by adding the adjuvant to the water first, in order to prepare the water for the pesticide and create the right chemical reactions.
“Managing hard water involves knowing what you are dealing with first,” Ziprick stated. “You need to know what cations are present and at what levels.”
Alkaline water conditions are also often problematic in that a pH of higher than 7 can cause some pesticides to break down. Similar to managing water hardness, adjuvants to manage pH should be added to the water first to minimize any breakdown of the pesticide.
With the numerous products on the market today, pesticide application is far from simple. Make the most of the time and money invested by seeking out adjuvants that will create the most compatible and ideally applied spray possible.
By understanding water quality and the overall properties needed, the right choices for pesticides and adjuvants can be made for the problem being managed
