What is in this article?:
- Accurate and efficient pesticide applications should increase efficacy, minimize drift and maximize productivity, says application technology specialist Robert Wolf.
- Nozzles can increase efficacy, but lead to more drift potential.
- Some newer nozzles can produce larger spray droplets to decrease drift, but at the same time can result in reduced coverage for controlling the targeted pest.
Spray nozzle is critical
“The nozzle is actually the working part of the sprayer,” Wolf explained. “It is very inexpensive but the most critical part of the system for droplet size control. Applicators should select the best nozzle to correctly apply pesticides while achieving the exact droplet size recommended on the pesticide product label.”
The correct nozzle also reduces spray drift and provides maximum effective spray quality and droplets. The nozzle atomizes the mixed solution. Generally, large droplets do not provide the best coverage or remain on the plant, but drift less. Smaller droplets have the potential to drift more, especially in higher winds.
Changes in nozzle designs used today began about 30 years ago with a major emphasis on drift reduction. At that time, the extended range flat-fan nozzle was introduced followed by chambered versions of a flat spray nozzle, and now most recently air induction or venturi-style flat fan nozzles. Each design change has resulted in more effective drift reduction.
Cone nozzles, previously prominent in some agricultural spraying settings, are not used much anymore since the fine droplets can result in more drift issues.
“Though useful when first introduced, I don’t recommend the extended range flat fan nozzle anymore,” Wolf said. “In most agricultural settings when the required gallons of pesticide per acre are low, this nozzle is not a good choice because it is more drift prone than the more recent designs. It is best used with application volumes of 10 gallons or more per acre; more commonly used with insecticides and fungicides.”
In field trails, Wolf studied the chambered turbo fan nozzle; an upgraded flat fan nozzle. Due to the chamber design, this nozzle provides good efficacy and less drift potential.
“This is the nozzle type which I generally recommend to applicators for general multi-purpose crop protection applications,” Wolf said.
The latest version of this nozzle is the turbo twinjet fan nozzle with the identical internal design as its predecessor. The nozzle has two exit orifices which change the droplet size to reduce the pressure of the applied droplet. Due to its dual angle spray, this nozzle works well for fungicide application in denser canopies, including treatments for wheat diseases.
The most recent designs are nozzle types utilizing air induction or a venturi. Air is drawn into the nozzle cavity and exits with the fluid reducing drift. This nozzle type is called different names by various manufacturers but for the most part all work the same.
Another new nozzle on the market is the turbo injection or TTI; a combination of the turbo flat fan and the Venturi internal chamber nozzles. The TTI has two chambers and larger droplets.
“In our droplet measurement tests, this tip has the largest droplets of any tip in the marketplace today. If you are going strictly for drift control then I would suggest this nozzle,” Wolf said.
Wolf concluded his presentation by examining a new concept in pesticide application – calibration of the spray droplet size. The industry is adopting a color-coded, eight-level droplet-size standard developed by the American Society of Agricultural and Biological Engineers.
“Instead of focusing on a numbering scheme for droplet size, we will now focus on categories from extra fine to ultra coarse,” Wolf said. “If a nozzle manufacturer wants to sell a nozzle, they’ll test the nozzle against the standard nozzle set in a lab using a laser beam measuring tool to classify the nozzle into categories based on the orifice size and pressure.”
Chemical companies will provide this droplet category information on product labels as a way to help applicators select and use the nozzle most effectively for crop protection products.
Wolf encourages new and experienced applicators to attend spray application workshops to learn the latest developments in the ever-changing pesticide application field.
“I encourage applicators to attend meetings and tradeshows to find out what’s available,” Wolf said. “Nozzle manufacturers have a pretty good handle on what they are selling. Search them out and talk with them.”