My path in agriculture was not straightforward. I grew up going to my grandparents’ cattle ranch in south Texas on the weekends. When I was very small, my Pappy would put me in a wheelbarrow to not only keep me somewhat contained, but to keep me safe from the cacti and rattlesnakes. As we walked around, he would talk about the farm and I became fascinated by it. Between these visits and my dad’s love of nature I decided that working with plants was my call. I worked in several natural systems but eventually found my way to row crops and weed science in graduate school. Since then, I’ve had the opportunity to work all over the U.S. in a wide variety of cropping systems (cotton, corn, soybean, wheat, rice, grain sorghum, sugarcane) in both academia (University of Arkansas and LSU AgCenter) and industry (Blue River Technology – John Deere See & SprayTM) settings. My agronomic and weed science background allows me a different perspective to precision agriculture and how it fits into farming today.
As we gear up for the 2026 field season whether you are broadcasting or target applying products with self-propelled sprayers, planes, drones, robots, etc. there’s a very small part that has a big impact on cotton production – nozzle tips. Nozzle decisions impact droplet size, spray drift potential, flow rate, spray pattern, compatibility with adjuvants and formulations, and spray coverage or deposition. Timely, on-target pesticide applications are critical for efficacy, ensuring proper coverage, and decreasing the risk of contamination from occurring.
First let’s talk about where you can get information about nozzles. Each nozzle distributer will have nozzle guides (TeeJet, Pentair Hypro, Wilger, Greenfield to name a few). These honestly can be confusing at times, but do have all necessary information you would need. On the nozzle tip itself, you will find the nozzle type, spray fan angle, and the flow rate (GPM). With that in mind, you will need to determine which nozzle size is needed. Nozzle sizing comes down to math – yes, math. The formula is: where GPM is gallons per minute at 40 PSI, GPA is gallons her acres, w is nozzle width/spacing in inches, and mph is sprayer speed in mph. The type of nozzle can change based on what kind of product (ex. herbicide vs. insecticide; systemic vs. contact) you are spraying, how you are spraying it (ex. broadcast vs. banded), and why (ex. weed control vs. drift mitigation; PRE vs POST emergence).
Cleaning and preparation before and during the field season are important to ensure your nozzles are working properly. Before the season begins, the entire nozzle body needs to be taken apart and visually examined, including the O-rings, filters, and nozzle tips for wear and tear, clogging, and ensuring that all parts match across the boom. Additionally, confirm that the remainder of your sprayer is clean. After spraying, drain the sprayer (including boom and lines). Avoid allowing the spray solution to remain in the spray boom lines overnight or for extended periods of time. Flush the tank, hoses, boom, and nozzles with clean water. Open boom ends and flush if so equipped. Inspect and clean all strainers, screens, and filters. Use commercial sprayer cleaner containing strong detergents according to the manufacturer’s directions. Flush hoses, spray lines, and nozzles with the cleaning solution. Remove nozzles, screens, and strainers, and clean separately in the cleaning solution after completing the above procedure. Triple rinse the complete spraying system with clean water. Appropriately dispose of all rinsate in compliance with local, state, and federal requirements.
Other considerations with nozzle selection include boom height, range of sprayer speed, proper mixing, and use of Pulse Width Modulation (PWM). Boom height will vary based on your nozzle spacing and nozzle angle. Consult with your nozzle guide or manufacturer to ensure proper boom height. The old “fill the tank 50 to 75% full, then add the herbicides” may not be advisable anymore. If using induction tanks, do not mix concentrated herbicides together. Instead start with the tank about 25% full, then add one herbicide, flush with water, then add the next herbicide, and flush with water. PWM systems can really help around field borders, site-specific applications, and application flexibility. If using a PWM some best use practices include using only non-venturi (non-air induction) nozzles, optimal duty cycle range is 50 to 100% (best recommendation is to stay between 70 to 90%), if drift mitigation is needed, a higher application pressure (greater than 40PSI) is recommended, and be aware of pressure loss through the solenoid valves.
The final question to ask is what are you trying to achieve in the field – what are you applying, are you trying to increase cover for weed control, insect or disease management (smaller droplet sizes and a higher PSI), are you applying harvest aides, or mitigating drift? For example, herbicide nozzles can act as a see-saw. On one side you have contact herbicides (ex. Liberty, Gramoxone) that need smaller droplets, whereas with systemic products (ex. Roundup, Styrax/Engenia/Tavium, Enlist One, etc.) larger droplets provide the same efficacy with reduced drift potential. The objective you are trying to achieve will help dictate the answer to which nozzle you will choose. Each of these questions have a different nozzle to achieve the best results. For optimal results, cotton growers should be aiming to use two to four different nozzle types throughout the growing season to answer a different question at a specific time of the year.
A few final reminders as you choose your pest management program – the label is the law. Keep in mind that some pesticides have nozzle restrictions or requirements. For example, dicamba products require coarse or coarser nozzle tips, think blue or green tips. A good guide is the ASABE S572.1 Droplet Size Classification Guide. Pesticides should also only be one part of your cotton management program, implementing an integrated management approach (ex. crop rotation, using multiple effective pesticide modes of action, tillage, varieties, scouting, etc.) is critical for maximizing yield and returns in your cotton crop.
As always, your UGA county extension agents and the rest of the cotton and precision ag teams are here to help you. If you have any questions about precision agriculture in cotton, please reach out. Here’s to another great field season!
Dr. Lauren Lazaro is an Extension Precision Agriculture Specialist and Assistant Professor with the University of Georgia’s College of Agricultural & Environmental Sciences. For more information, please contact Dr. Lazaro at lauren.lazaro@uga.edu or 210.562.0878.