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For the 2018 dicamba application season, the EPA has suggested changes to the labels for XtendiMax, FeXapan, and Engenia.  Specifically, for the purposes of this post, the recommended minimum GPA has been adjusted/suggested to be 15 GPA.  The increased GPA will help achieve better coverage while at the same time helping keep application speeds lower. The goal being to improve efficacy and help mitigate spray drift.

The maximum application speed remains at 15 MPH.  Speed in combination with GPA will influence the pressure used during the application. Though not specifed on the 2018 version of these labels, it remains essential to maintain a higher pressure when using venturi nozzles. Research supports better efficacy at the higher pressures (30-60 PSI), while still having a very low driftable fines content.  When using a rate controller, the speed changes will infuence pressure.  As we know, higher speeds will result in higher pressure and lower speeds will result in lower speed, given the same nozzle orifice size.  What is critical with the application of these products when using venturi type nozzles (as approved by the EPA), is maintaining a pressure  that is high enough to maintain a sufficient droplet size to maximize coverage.  If the pressures are allowed to drop too low, then the droplets will become larger, which is good for drift mitigation, but not necessarily supportive of the weed control needed.  On the flip side of that is when the speeds are increased causing higher pressure, more drift is likely and the application will become off-label due to the smaller droplets being created.  Every nozzle, chemical, adjuvant, and DRA on the approved list has been placed there based on wind tunnel data and using the AGDISP Model to ensure a low drift profile as established by the EPA.  Any variations from the label specified requirements are potential off-label applications.

It is also important to understand the influnce of using DRA's as required for the application of these products.  It is known that certain nozzle types in combination with a DRA and low pressures may negatively influence the spray pattern quaility, resulting in bigger droplets and poorer coverage with less control.  This is another reason to maintain the higher pressures needed to effectively operate a venturi designed nozzle with these products.

To help applicators understand the limitations imposed with the 15 MPH and 15 GPA requirements, I have prepared the two following documents doing the math to show the relationship between GPA, MPH, and PSI.  The calculations are for all the approved nozzle orifice sizes (03, 04, 05, 06) and are based on 15-inch and 20-inch nozzle spacings.  The results will be different for each nozzle spacing.  These charts are for conventional spray booms only and will not reflect any of the pulse width modulation (PWM) sprayers.  All the formulas used to determine GPM and PSI calculations are footnoted in the documents.  The acceptable combinations are based on a pressure range considerd appropritate (by the author) or otherwise specified on the label or in the manufacturers literature.  I am basically using a pressure range of 40-63 PSI (exceptions are noted).  The charts also reflect a precaution about the recommended slowdown around the edges of the field.  Note that the pressures in those situations are well below what would be necessary to maintain a quality application.

It is my recommendation that as sprayer operators, instead of using your speedometer to monitor your travel speed, pay close attention to your pressure gauge and use it as your speedometer, maintaining the PSI range that has been suggested for the nozzle being used.  Know your nozzles operating "Sweet Spot".  That may not be the manufacturers advertised pressure range. 

As mentioned in the documents, I have utilized the University of Illinois Smart Phone or Tablet App - SPRAYER CALIBRATION CALCULATOR  to make all the necessary calculations for these charts.  That app is available through Google Play or the App Store on your phone or tablet.

Please report any calculation errors.


15-inch nozzle spacing - MPH & PSI Options for selected GPA's

20-inch nozzle spacing - MPH & PSI Options for selected GPA's

Application Record Keeping: A Protocol for Documenting the Weather

One of the new requirements for the application of XtendiMax, FeXapan, and Engenia will be for applicators to keep records for each application.  Applicators are always expected to be good stewards when applying crop protection products, especially with these dicamba based products.  With a major emphasis on avoiding spray drift into sensitive areas, a critical part of keeping good records includes accurately recording the environmental data associated with each application.  A document has been developed to help applicators establish a protocol for recording consistant and accurate weather records.  Use the following link to access that document.

Application Record Keeping: Focus on Environmental Conditions

A recent visual inspection of venturi nozzles used at low pressure in combination with a DRA reveals that several nozzles on the dicamba 'approved list' may not provide a suitable pattern that could effect coverage, which may also result in poor weed control.  Review the information reported at this link.

Pattern Quality Issues


The recent EPA approvals of XtendiMax w/VGT (Monsanto), FeXapan w/VGT (Dupont), Engenia (BASF), and the earlier approval for Enlist Duo w/Colex-D (DAS) have presented new challenges for the application industry.  Spray system operators will now be required to adhere to some very detailed specifications regarding the setup and operation of the sprayers used to apply these products.  This has not always been the case in years past.  Labels of the future are expected to take on this new format.  Especially, as we enter into an era of applying crop protection products designed for making applications to herbicide tolerant crops for the purpose of controlling resistant weeds.  For example, in the three crop protection products listed above; nozzle type and size, pressure, droplet size, ground speed, and spray boom height, are among some of the parameters that are specified.

It will be paramount that all involved in the application decision making process read, understand, and follow the current version of the label before making any applications. Nothing has changed, the label is a legal document, and must be followed in order to safeguard the availabilty of these new chemical technologies.

 A chart contrasting and comparing the specified application parameters for these products has been prepared to help make sound decisions regarding their application.  The information provided in this chart is based on the instructions contained in each label, the authors interpretation of those instructions, and also contains editorial comments from the author.  The comments are to further emphasize proven application strategies and practices to ensure good stewardship while making successful applications.  Use this link to access this document.

Application Comparison Chart - Version 6

Pollinator Protection

Pesticide risk management must be based on sound science, consistent with the laws under which pesticides are regulated in the United States. EPA has been working aggressively to protect bees and other pollinators from pesticide exposure.  Proposing a plan to prohibit the use of pesticides that are toxic to bees when crops are in bloom and bees are under contract for pollination services. The plan also recommends that states and tribes develop pollinator protection plans and best management practices. For more information on steps to protect pollinators, link to this EPA site.

Additional information on State pollinator protection plans and pollinator health reports can be found on the following website.  Pollinator Stewadship Council.

Information regarding pollinator protection is also available through FieldWatch/DriftWatch. The BeeCheck program is a voluntary communication tool that enables beekeepers and pesticide applicators to work together to protect apiaries through use of the BeeCheck mapping program. Likewise, pesticide applicators utilize the site to help determine the location of specialty crops and beehives in their trade areas. DriftWatch and BeeCheck provides the platform to facilitate better awareness, communication and interaction between all parties as one part of ongoing stewardship activities.


EPA Worker Protection Standard Revisions

Worker Protection Standard: EPA's Agricultural Worker Protection Standard (WPS) is aimed at reducing the risk of pesticide poisoning and injury among agricultural workers and pesticide handlers. The WPS offers occupational protections to over 2 million agricultural workers (people involved in the production of agricultural plants) and pesticide handlers (people who mix, load, or apply crop pesticides) who work at over 600,000 agricultural establishments (farms, forests, nurseries and greenhouses).  For more details, use the link above.

WPS Revisions:  EPA is announcing stronger protections for the nation’s two million agricultural workers and their families working on farms, forests, nurseries, and greenhouses. These revisions to the 1992 Agricultural Worker Protection Standard will afford farmworkers similar health protections that are already afforded to workers in other industries.  For more details, use the link above.

Application Exclusion Zone:  A major addition to this revision is the Application Exclusion Zone (AEZ).  New no-entry application-exclusion zones up to 100 feet surrounding pesticide application equipment will protect workers and others from exposure to pesticide overspray.  This will be based on the ASABE S-572.1 for classifying spray droplet sizes.  Refer to the above link for additional details.

WPS Train-the-Trainer Criteria and Process:  EPA’s revised Worker Protection Standard (WPS) was published as a final rule on November 2, 2015.  The 2015 revision requires persons seeking to become trainers of workers and handlers through completing a Train-the-Trainer program to qualify by completing an EPA-approved Train-the-Trainer (TTT) program. This requirement becomes effective on January 2, 2017, meaning that a person must complete an EPA-approved program before that date to qualify as a WPS pesticide safety trainer for workers and/or handlers. EPA has prepared guidance material to facilitate the development of programs that meet EPA requirements.  The above link will take you to the EPA guidance document.


FieldWatch is a non-profit company that offers mapping and communication tools which are just one element of a successful formula for successful co-existence of specialty producers, large scale commodity farmers, commercial and private applicators and beekeepers.  Communication is the start, but cooperation and collaboration of all parties is essential.  Sometimes it means compromise or adjustments that foster an environment that everyone can do what they need to do with respect to the needs of others.

The DriftWatch-Registries site is a voluntary communication tool that enables crop producers, beekeepers, and pesticide applicators to work together to protect specialty crops and apiaries through use of mapping programs. It is not a substitute for any state regulatory requirements.  With DriftWatch, producers of high-value specialty crops, such as tomatoes, fruit trees, grapes and vegetables, register their sites on-line and provide contact information about their operation. With BeeCheck, beekeepers register their hives on-line and provide contact information.  Likewise, pesticide applicators utilize the site to help determine the location of specialty crops and beehives in their trade areas. DriftWatch and BeeCheck provides the platform to facilitate better awareness, communication and interaction between all parties as one part of ongoing stewardship activities.

Drift Reduction Technology - DRT

Drift Reduction Technology Program Description:

The EPA's purpose for the Drift Reduction Technology (DRT) Program is to encourage the manufacture, marketing, and use of spray technologies scientifically verified to significantly reduce pesticide drift. Initially, the focus of the program is on spray technologies used primarily for pesticide applications to row and field crops by ground or aerial application equipment. Plans to expand this program to include technologies for orchard and vineyard crops are being considered.

To participate, technology manufacturers are encouraged to test their technologies for drift reduction potential. Test protocols have been provided to guide these evaluations.

Technologies include but are not limited to:

• Nozzles
• Spray shields
• Drift reducing adjuvants with adjuvants defined as any substance separately added to a pesticide product (typically as part of a spray tank mixture), that will improve the performance of the pesticide product.

The EPA will use a rating system to indicate the level of potential drift reduction of tested technologies. Based on review of submitted test results, a DRT rating will be assigned, using one to four stars, to each technology that meets the minimum standard for drift reduction. Pesticide manufacturers will be encouraged to state on their product labels that applicators should use DRT-rated technologies in applying pesticide products.

Benefits of Using Drift Reduction Technology:

Using DRT-verified pesticide spray technology can benefit pesticide applicators, the environment and people by:

• reducing loss of pesticide from the application site,
• keeping more of the applied pesticide on the crop, improving pest control,
• reducing pesticide exposures to people, wildlife, and the environment, and
• reducing risks of damage and liabilities from off-target deposition of drift.

The use of DRTs should result in significantly less pesticide from spray applications drifting and being deposited in areas not targeted by those applications, compared to spray technologies that do not meet the minimum DRT standard. As a result the EPA may place fewer use restrictions on pesticide products that must be used in conjunction with DRTs.