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Sentris and Glyphosate Tank-Mix Compatibility Problems
By: Tommy Butts, Tom Barber, and Jason Norsworthy
We’ve had several reports of applicators experiencing issues when tank-mixing products
with Engenia and the new volatility reducing agent (VRA) from BASF, Sentris. Applicators
have stated that they are experiencing extreme amounts of foaming from the tank and
even a few reports of enough pressure being generated to pop the lids off of their
spray tank, specifically inductor tanks (Fig. 1).
As a result of these calls, we decided to do a few small scale “jar” tests in 3L bottles
to determine if we could find the cause or reproduce these reported issues. We have
created a video highlighting our tests and providing a demonstration of the results.
This video can be found here: http://bit.ly/Sentris-Gly-Mix. To accompany our video, methods and results of the jar tests are discussed below.
For this compatibility test, multiple herbicides and VRA’s were evaluated (Table 1).
The Sentris was purchased from a local cooperative and as such was a commercially
available product. The water used as the carrier had been previously analyzed with
the following results: pH=7.0, “Soft” hardness classification based on calcium (Ca+2) and magnesium (Mg+2) concentrations, and minimal iron (Fe+3) and sodium (Na+) concentrations. Additional tests with distilled water were also conducted. Calculations
were done to determine the amount of each chemical necessary for a 3L bottle that
would match label rates and assume a 15 gallon/acre spray volume. These rates are
also provided in Table 1. Please note that at this time, Cornerstone Plus and Interline
are both illegal tank-mixture options with Engenia (or XtendiMax and Tavium) according
to the federal label, and any glyphosate product is prohibited from tank-mixture with
Engenia (or XtendiMax and Tavium) in the state of Arkansas. These were included for
research evaluation purposes only.
Table 1. Herbicides and volatility reduction agents (VRA) with their rates used in compatibility
testing. All mixes were made assuming a 15 gallon/acre spray volume.
Chemical Herbicides: (Trade name)
Chemical (active ingredient)
Use Rate (fl ox/A)
Roundup PowerMax 2
Glyphosate (K salt)
Roundup PowerMax 3
Glyphosate (IPA salt)
The mixing order was also changed with several mixtures to evaluate any differences
that occurred if Sentris was added into the spray solution first or if it was added
into the mix after the herbicides. Further jar tests evaluated whether the amount
of initial water in the bottle (0.5L versus 1.5L versus 2.5L) prior to mixing altered
any response. A final test was also conducted to evaluate if the addition of a defoaming
agent (Foam Breaker) would alter the resulting response.
Overall, the results indicated a severe incompatibility problem when glyphosate, Engenia,
and Sentris were mixed. This is especially demonstrated in the corresponding video
previously referred to and found here: http://bit.ly/Sentris-Gly-Mix. When glyphosate, Engenia, and Sentris were mixed, a chemical reaction occurred within
the solution releasing an unknown gas pressurizing the bottle. Additionally, increased
foaming occurred and when the bottle was opened to release the pressure, the foam
sprayed out of the bottle. This was not limited to a single glyphosate product or
glyphosate salt; instead, the same result occurred for each glyphosate tested (Roundup
PowerMax 2, Roundup PowerMax 3, and Cornerstone Plus). Furthermore, this was not limited
to a singular water quality source. The same reaction occurred even when distilled
water was used as the carrier, and the results observed in these tests in Arkansas
were also observed by university collaborators in other states (using different sources
No other herbicide tank-mixtures, including Engenia plus Sentris without glyphosate,
caused this increased foaming and gas release. Even Interline, which is typically
expected to foam more, did not result in the same level of foam production or result
in a release of an unknown gas similar to the glyphosate, Engenia, and Sentris mix.
Mixing order and amount of water in the bottle also did not influence this result.
Per BASF recommendations, some tests included 1.5L of water (50% of final required
volume), Sentris added to the bottle first and shaken, followed by the addition of
Engenia and glyphosate. This mixing order still resulted in the chemical reaction
occurring, gas being produced, and high levels of foam spewing from the cap. Although
this mixing order did not solve the problem at hand, since Sentris and VaporGrip Xtra
are considered water conditioning adjuvants, it is still recommended that these products
be added to the tank first to begin conditioning the water prior to the addition of
any other products.
When Foam Breaker was added into the spray solution first, the glyphosate, Engenia,
and Sentris mixture resulted in little to no foam occurring; however, the same unknown
gas was still produced significantly pressurizing the bottle. Finally, the tank-mixture
of glyphosate, Engenia, and VaporGrip Xtra did not result in any negative compatibility
issue as far as increased foaming or gas production.
There was an incompatibility identified when tank-mixing Engenia, glyphosate, and
Sentris resulting in a significant increase in foaming and an unknown gas that pressurized
the bottle. This increased foaming has also resulted in other reports of problems
effectively spraying the tank-mixture and maintaining an appropriate spray pattern.
It is once again important to note that this tank-mixture is prohibited within the
state of Arkansas. But, if used outside of Arkansas, it is recommended to avoid the
tank-mixture of glyphosate and Engenia (or XtendiMax and Tavium) due to herbicide
antagonism, improper nozzle options for grass control, and now the recently identified
incompatibility between the VRA Sentris and Engenia plus glyphosate. If glyphosate
must be mixed with Engenia, it is recommended to use VaporGrip Xtra as the mandatory
VRA tank-mix partner as the incompatibility issue was not observed with this VRA.
University testing of Sentris was extremely limited prior to its commercialization,
and as a result we are learning as we go. Further tests will be conducted in the future
to better understand this reaction, and search for solutions for our farmers and applicators.
If you observe any complications or have any questions, please don’t hesitate to reach
out to us.