NDSU Crop and Pest Report
Weeds


ISSUE 10   July 8, 2004

GLYPHOSATE UPDATE - PART 1

The following is a short summary of several glyphosate products from Monsanto and Syngenta.

RU Original, a 3 lb ae/gal, isopropyl amine salt, partial adjuvant load formulation has been discontinued. All current inventory will be sold.

RU OriginalMax, a 4.5 lb ae/gal, K-salt, full adjuvant load formulation is new for 2004. This formulation contains a Transorb II adjuvant system which is guaranteed to be rain-fast within 1 to 2 hours after application and can be used on RUR crops.

RU Ultra, a 3 lb ae/gal, isopropyl amine salt, full adjuvant load formulation has been discontinued. All current inventory will be sold.

RU UltraMax, a 3.7 lb ae/gal, isopropyl amine salt, full adjuvant load formulation has been discontinued. All current inventory will be sold.

RU UltraMax II, a 4.5 lb ae/gal, K-salt, full adjuvant load formulation is new for 2004. This formulation does NOT allow additional surfactant, contains a Transorb II adjuvant system which is guaranteed to be rain-fast within 0.5 hour after application, and can be used on RUR crops.

RU WeatherMax, a 4.5 lb ae/gal, K-salt, full adjuvant load formulation was available in 2003 and is available for 2004. This formulation does not allow addition surfactant, contains a Transorb adjuvant system which is guaranteed to be rain-fast within 0.5 hour after application, and can be used on RUR crops.

RT Master, a premix formulation of 3.7 lb ae/gal glyphosate + 0.32 lb/gal 2,4-D has been discontinued. All current inventory will be sold.

RT Master II, a 4.5 lb ae/gal, K-salt, full adjuvant load formulation is new for 2004. This formulation does NOT contain 2,4-D, but contains a blue color, a Transorb adjuvant system which is guaranteed to be rain-fast within 1-2 hours after application, is only available in bulk, and CANNOT be used on RUR crops.

Touchdown iQ, a 3 lb ae/gal, 2-NH3-salt, full adjuvant load formulation is also available in 2004. This formulation contains an iQ adjuvant system which improves rain-fastness, and can be used on RUR crops.

Touchdown CF, a 3 lb ae/gal, 2-NH3-salt, full adjuvant load formulation is also available in 2004. This formulation contains an iQ adjuvant system which improves rain-fastness, but CANNOT be used on RUR crops.

Touchdown Total, a 4.17 lb ae/gal, K-salt, full adjuvant load formulation is new for 2004. This formulation contains an iQ adjuvant system which improves rain-fastness, and can be used on RUR crops.

Touchdown HiTech, a 5 lb ae/gal, K-salt, NO adjuvant load formulation is new for 2004. This formulation contains NO adjuvant and additional surfactant must be added for effectiveness. Touchdown Hi-Tech can be used on RUR crops.

 

ARE ALL GLYPHOSATES THE SAME?

All U.S. glyphosate products on the market are formulated with one three salts: isopropyl amine (ipa), potassium (K), and diammonium ((NH4)2). Why formulate with salts? Because glyphosate is a weak acid herbicide, as are many herbicides on the market (2,4-D amine, dicamba, Pursuit, Raptor, Basagran, Sus). Weak acid herbicides do not dissolve easily in water so the manufacturer formulates the active ingredient with a "salt" which allows the herbicide to dissolve. The table below summarizes the different salt formulations of glyphosate:

Glyt-ipa salt

Glyt-(NH4)2 salt

Glyt-K salt

Most glyphosate products on the market - see page 68 of the 2004 ND Weed Guide.

Touchdown iQ
Touchdown CF

RU OriginalMax
RU UltraMax II
RU WeatherMax
RT Master II
Touchdown Total

In the case of the new glyt-K salt formulations where K is a smaller molecule than the ipa salt, more glyphosate can be added to the formulation (See #4 below). Considering the amount of glyphosate used in the U.S., this greatly reduces the amount of product transported and space needed in warehouses. With the many generic glyphosates on the market, a few pointers should be remembered.

http://www.kellysolutions.com/nd/

  • For glyphosate products, does the label state that additional surfactant needs to be added to the spray solution? Some unloaded (no surfactant in the formulation), or partially loaded (contain some surfactant but requires additional amount) formulations like RU Custom, RU Original, Touchdown HiTech require surfactant but other like RU WeatherMax, Glyphomax Plus, or Touchdown Total do not require addition of surfactant.
  • 3 lb ae/gal = Most generic glyphosate on the market.
    3.7 lb ae/gal = RU UltraMax - to be phased out
    4 lb ae/gal = RU Custom, Rodeo - they have no adjuvant load
    4.17 lb ae/gal = Touchdown Total - new for 2004
    4.5 lb ae/gal = Most new K salt formulation are this type
    5 lb ae/gal = Touchdown HiTech - no adjuvant load.

    The lbs of ai/gallon cannot be used make glyphosate rate comparisons because the three different salts (ipa, (NH4)2, and K) have different weights and the salt does not contribute to killing weeds. It is only the amount of pure glyphosate (ae) in the container that is needed when comparing rates.

    In summary:

    active ingredient (ai)/gallon = wt of glyphosate + wt of salt
    acid equivalent (ae)/gallon = wt of glyphosate

    The following table may help simplify calculating the amount of product needed per acre when choosing any particular glyphosate formulation.

     

    Glyphosate product rates based on formulation, acid equivalent (ae) and active ingredient (ai) rate. Pounds ae or ai are found on glyphosate product labels.

     

    Lbs ae/A

    Lbs/gallon

    0.38

    0.57

    0.75

    1.125

    1.5

     

    --------------- fl oz/A --------------

    3 lb ae/4 lb/ai

    16

    24

    32

    48

    64

    3.7 lb ae/5 lb/ai

    13

    20

    26

    40

    52

    4 lb ae/5.4 lb/ai

    12

    18

    24

    36

    48

    4.17 lb ae/5.1 lb/ai

    12

    18

    24

    36

    48

    4.5 lb ae/5.5 lb/ai

    11

    16

    22

    32

    44

    5 lb ae

    10

    15

    20

    30

    40

    For example, if you have been using 2 pt/A = 32 fl oz = 0.75 lb ae/gal of 3 lb ae gallon glyphosate formulation like Roundup Original, Buccaneer or many other products listed on page 68 of the 2004 ND Weed Control Guide then the equivalent rate of the new Roundup WeatherMax or Roundup Ultra Max II (4.5 lb ae/gal) would be 22 fl oz/A.

    This chart is in each table of the 2004 ND Weed Control Guide where glyphosate is listed, except it does not list Touchdown HiTech (5 lb ae/gal) which was registered just a few weeks ago.

  • How does the cost of different glyphosate formulations with the same ingredient compare? The simplest way to make this comparison is to calculate the cost/lb of ingredient. Hypothetically, if a generic 3 lb ae/gal product costs $30/gallon and RU WeatherMax cost $50/gal:

  • Generic = $30/3 = $10/lb
    RU WeatherMax = $50/4.5 = $11.10/lb

    With these hypothetical values, generic glyphosate would cost slightly less to get the same amount of glyphosate.

    Richard Zollinger
    NDSU Extension Weed Specialist
    r.zollinger@ndsu.nodak.edu


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