By Erdal Ozkan, Professor and Extension Agricultural Engineer, The Ohio State University
Generally, this is the time of the year you complete shopping for nozzles because the spraying season is just around the corner. This task must be on top of your to do list if you are one of those who will be applying the new 2,4-D or Dicamba products for crops that are resistant to these products.
According to a survey conducted by Farm Journal magazine and reported in its Mid-February issue, out of the 411 people they contacted (mostly in Midwest, including Ohio) 40% of them indicated they plan to grow dicamba-tolerant soybeans. About 11% indicated they are still undecided. If you happened to be one of these people who will use dicamba products for weed control, you better check the labels because you now have to use one of the nozzles they recommend on their labels, and operate those nozzle within a recommended range of pressures.
In the past, the labels on chemicals gave some vague and general statements when referring to application equipment. For example, we used to see (it is still the same for many chemicals) on labels statements such as: “use spray equipment to provide thorough coverage of the canopy.” There was no help with explaining what “thorough coverage” is, and how to achieve it. Then, we saw labels giving us more specific recommendations on nozzles such as: “use nozzles that provide medium spray quality” or “do not use nozzles that produce droplets in coarse or larger spray qualities.” Most recently, the labels of the new 2,4-D or dicamba herbicides include very specific requirements on which nozzle or nozzles must be used when spraying these products. Simple interpretation of this requirement is that you would be violating the label if you use any other type or size of nozzle. So, it is your responsibility to comply with the label recommendation.
Why are specific nozzles required by manufacturers of 2,4-D and dicamba herbicides?
Manufacturers of these new products claim that they have significantly reduced the drift potential due to volatilization, as was the case with similar products used decades ago. However, they are extremely concerned about the physical drift (actual droplets moving by wind to sites adjacent to the application site) may happen and create significant damage to crops grown nearby that are not dicamba resistant. With this in mind, the manufacturers of these products have decided on requiring sprayer operators to use specific nozzles and run the sprayer within a specific range of pressures to make sure physical drift is very unlikely to take place during spraying. After completing extensive tests in wind tunnels, manufacturer of 2,4-D product (Enlist Duo) chose 23 nozzles, while manufacturers of dicamba Products (XtendiMax, FeXapan and Engenia) chose a total of 24 nozzles that must be used to spray these products. In most cases the nozzles recommended for different products may be the same, but there may be significant differences in the operating pressures required. For example, the ULD20-04 nozzle is selected by all four products mentioned above, but the pressure ranges required for them are somewhat different: 15-70 psi for Enlist Duo, 20-40 psi for XtendiMax and FeXapan, and 15-40 psi for Engenia. The Table shown below lists all the nozzles and their operating pressures required by manufacturers of the four products listed above. A caution: this table is provided mostly for information purposes and may not be up-to-date. You are always advised to look at the label for the most current information.
By the way, don’t assume that you do not have to worry about checking the label this year again because you had applied a dicamba product made by a different company last year. A nozzle required for the same product last year may not be on the label this year, or the operating pressures may be changed. So, you really need to pay attention to the label for each product even if you are using the same product you had used last year. Things were much easier during the last decade when product labels did not require specific nozzles. Instead, they required the most optimum droplet size class, such as Fine, Medium, Coarse, Extra Coarse, Ultra Coarse, etc. for their products. So, if you were looking for a nozzle that produced Medium droplets, all you had to do was to look at the nozzle catalogs (or search online) find a suitable type of nozzle that would provide Medium droplet class at a pressure setting that would also satisfy your gal/acre requirement. Interestingly, when I looked at all the nozzles and operating ranges required for the new 2,4-D or Dicamba products, all the requirements have led to one common conclusion: the droplet size class from these nozzle fell in two categories: “Extra Coarse”, or “Ultra Coarse.” Our research have shown that regardless of the nozzle used, as long as the droplet size class, even at wind speeds of 10 miles per hour (the upper limit mentioned on labels) fall in either one of these categories, droplets will not likely to drift more than a foot or two (depending on other conditions such as boom height, temperature and relative humidity). So, it would have been much easier for you to select your own nozzle as long as the nozzle, when operated within a certain pressure range, satisfied the droplet size requirement of “Extra Coarse” or “Ultra Coarse”. But that is another topic of discussion left for another day.
Act now if you will be switching to new nozzles. If you are buying new nozzles of any kind, or especially if you are going to switch to one of the new 2,4-D or dicamba herbicides this year and you have not purchased yet the specific nozzles required for these products, you better act fast and get the nozzles within the next two weeks. Since there will be a higher demand for nozzles of any kind this time of the year, there may be short-term shortages of these nozzles in stores from which you purchase your nozzles. So, act now and get the nozzles you need before experiencing potential problems with availability of these nozzles later during the spraying season.
Keep several types of nozzles on the boom
It is very likely that you will be using your sprayers to spray a variety of pesticides during the growing season. Remember that one specific type of nozzle will not be best for all applications. For that reason, it is best to have several types and sizes of nozzles on the boom so that you can switch to the “best” nozzle choice for a given spraying job. There are various types of sprayer components and setups you can buy to configure your boom so the new set up allows you to easily switch from one nozzle to another instantly.
Some final thoughts
Nozzles are typically the least costly items on a sprayer, but they play a key role in the final outcome from a spraying job: achieving maximum efficacy from the pesticide applied while reducing the off-target (drift) movement of pesticides to minimum. Pesticides work well if the rates on labels are achieved during application. This can be achieved only if the right nozzle type and the proper size of the nozzles are on the sprayer, and the sprayer is calibrated and operated properly.
Although the Apps and tables in catalogs may expedite the nozzle size selection process, it is best to understand the process and the math nozzle manufacturers use to generate the data listed in their tables, and to generate nozzle recommendations in their Apps. A new Ohio State University Extension Publication, entitled “Selecting the Best Nozzle for the Job” gives step-by-step guidelines for selecting the most appropriate spray nozzle for a given application situation. The publication is available online at following web site: http://ohioline.osu.edu/factsheet/fabe-528
I need to emphasize one other point: nozzles and their operating pressure requirements are not the only requirements you need to worry about when you are applying 2,4-D and dicamba products. There is additional important information as these requirements on product labels, such as: what part of the day these products should be applied, the buffer zone requirements, under what temperature and wind speed conditions you can apply them, or if there is a date beyond which these products cannot be applied. So, again you need to read labels of these products so that you are not held liable for an unfortunate misapplication situation, and consequently injury caused to sensitive crops near the application site.
Finally, always keep safety in mind when working with chemicals, especially pesticides. Always try to minimize oral, dermal or inhalation exposure to chemicals. Wear protective clothing when calibrating, spraying and cleaning equipment. Goggles, rubber gloves and respirators or masks are standard equipment when handling pesticides. Review the sprayer operator’s manual and chemical labels for recommended procedures regarding safe use of equipment and chemicals.
Erdal Ozkan, Professor and Extension Ag Engineer, can be reached at 614-292-3006, or email@example.com. This column is provided by the OSU Department of Food, Agricultural and Biological Engineering, OSU Extension, Ohio Agricultural Research & Development Center, and the College of Food, Agricultural and Environmental Sciences.