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ISSUE #11   July 12, 2001

 

GLYPHOSATE FORMULATIONS

Roundup (Monsanto)

Mode of action: EPSP synthase inhibition
a.i.: glyphosate
Crops: Various
Comments:. Glyphosate formulations can vary greatly in price depending on amount of acid equivalent per gallon and adjuvant load. Prices as low as $25/gallon has been reported for generic brands.

Glyphosate is available under the following labels:

  1. 3 lb ae/gal ipa salt with full, partial or no adjuvant load.
  2. 3 lb ae/gal (NH4)2 salt with full adjuvant load. Touchdown 3
  3. 3.7 lb ae/gal ipa salt with full adjuvant load. - Roundup UltraMax
  4. 4 lb ae/gal ipa salt without adjuvants. - Several generics
  5. 65% SG NH4 salt with full adjuvant load. (Roundup Ultra Dry)

The chart below lists several glyphosate products by company, salt, and adjuvant load.

Registered Glyphosate Products:

Trade Name

Manufacturer

Active ingredients

lb ai or ae/gal

Adjuvant Load*

Backdraft

BASF

gly-ipa + imazaquin

1.25+.25

None

Campaign

Monsanto

gly-ipa + 2,4-D-ipa

1.2 + 1.9

None

Cornerstone

Agriliance

glyphosate-ipa

3

Partial

Engame

UAP

glyphosate-AMADS

1.23+9.1

Partial

Expert

Novartis

s-metolachlor + atrazine + gly-ipa

1.73 + 2.13 +1

None

Extreme

BASF

imazethapyr + gly

0.17 + 2

None

Fallowmaster

Monsanto

gly +dicamba acid

1.1 + 0.5

None

Fallow Star

Albaugh

gly +dicamba acid

1.1 + 0.5

None

FieldMaster

Monsanto

acetochlor + atrazine +gly-ipa

2 + 1.5 + 0.56

None

Gly-Flo

Micro Flo

glyphosate-ipa

3

Partial

Glyfos

Cheminova

glyphosate-ipa

3

Partial

Glyfos X-tra

Cheminova

glyphosate-ipa

3

Full

Glyphomax

Dow

glyphosate-ipa

3

Partial

Glyphomax Plus

Dow

glyphosate-ipa

3

Full

Glyphosate Herb.

DuPont

glyphosate-ipa

3

Partial

Glyphosate Orig.

Griffin

glyphosate-ipa

3

Partial

Glypro

Dow

glyphosate-ipa

4

None

Glypro Plus

Dow

glyphosate-ipa

3

Full

Gly Star 5

Albaugh

glyphosate-ipa

3.7

Partial

Gly Star Original

Albaugh

glyphosate-ipa

3

Partial

Gly Star Plus

Albaugh

glyphosate-ipa

3

Full

Landmaster BW

Monsanto

gly-ipa + 2,4-D-ipa

0.9 + 1.5

None

Land Star

Albaugh

gly-ipa + 2,4-D-ipa

0.9 + 1.5

None

Protocol

Monsanto

glyphosate-ipa

3

Partial

Rattler

Helena

glyphosate-ipa

3

Partial

ReadyMaster ATZ

Monsanto

atrazine + gly

2 + 1.5

None

Rodeo

Monsanto

glyphosate-ipa

4

None

Roundup Custom

Monsanto

glyphosate-ipa

4

None

Roundup Original

Monsanto

glyphosate-ipa

3

Partial

RU Original RT

Monsanto

glyphosate-ipa

3

Partial

RU SoluGran

Monsanto

glyphosate-NH3

86.5%

None

RU/Private labels

Various

glyphosate-ipa

3

Partial

Roundup Ultra

Monsanto

glyphosate-ipa

3

Full

Roundup Ultra RT

Monsanto

glyphosate-ipa

3

Full

RU UltraDry

Monsanto

glyphosate-NH3

65%

Full

RU UltraMax

Monsanto

glyphosate-ipa

3.7

Full

Silhouette

Various

glyphosate-ipa

3

Partial

Touchdown 5

Syngenta

glyphosate-tms

3.45

Partial

Touchdown 3

Syngenta

glyphosate - 2(NH3)

3

Full

* Full = No additional NIS needed.
   Partial = Additional NIS needed.
   None = Additional NIS at full rate required.

Richard Zollinger
NDSU Extension Weed Specialist
rzolling@ndsuext.nodak.edu

 

ASPECTS OF APPLYING HERBICIDES AT LOW SPRAY VOLUMES

In my last article, I discussed how several POST herbicides are equally or more effective when applied in low spray volumes (2.5 to 5 gpa) with the proper adjuvant rate. This article will provide a little more background on applying herbicides in low volumes and address some of the concerns regarding low volume application.

One question that is often raised is will the spray coverage be sufficient enough to maintain effective weed control. In most situations, it will. It is correct to assume the total spray coverage will decrease as spray volume decreases since less water is being delivered to the plant. But the numbers of drops delivered to the target weed at low volumes is still sufficient for excellent weed control with the highly active translocated herbicides that are currently used. The following table illustrates this point.

Spray drop
diam.(um)

Spray Volume

2.5 gpa

5 gpa

10 gpa

20 gpa

 

drops per sq. in.

200

360

720

1440

2880

300

107

214

428

856

400

45

90

180

360

500

23

46

92

184

Even when spraying with nozzles that produce large spray drops up to 500 mm in diameter, 23 drops per square inch are delivered at 2.5 gpa spray volume, which should be adequate to cover even small target weeds.

Additionally, applying more spray to each plant does not necessarily result in a greater amount of herbicide remaining on each plant. Our research has, in fact, showed just the opposite. When comparing herbicide retention at 5, 10, and 20 gpa (volume changed by speed so the droplet size spectrum was similar among spray volumes), less herbicide remained on the plant at 20 gpa compared to 5 or 10 gpa. Herbicide concentration increases proportionately as spray volume decreases, so that an equal amount of herbicide is delivered to each plant, regardless of spray volume. In other words, a greater proportion of the herbicide delivered to the plant is retained when spray volume is 5 or 10 gpa rather than 20 gpa. This may be due in part to spray runoff at 20 gpa. While spray runoff may be desirable for canopy penetration, it is generally not a desirable aspect for most weed control situations.

Will herbicides perform well in low spray volume with dew present on weeds is another common concern. First of all, as the spray combines with the dew, spray runoff will more likely occur at high spray volume compared to low spray volume, thereby reducing the amount of herbicide remaining on the plant. Also, important is the increased herbicide and/or adjuvant concentration as volume decreases. The spray mixture is diluted when it combines with the dew, but remains more concentrated with low spray volume compared to high spray volume. Herbicide absorption increases as concentration increases for several herbicides including glyphosate (Roundup) and sethoxydim (Poast). Likewise, the adjuvant concentration would be greater for low volume application compared to high volume, which would be beneficial for both herbicide retention and absorption.

The increased herbicide and particularly adjuvant concentration with low spray volumes is also important when controlling weeds under stress. Herbicide absorption can be a limiting factor for controlling stressed weeds and the greater the adjuvant concentration in the spray mixture, the greater the herbicide absorption. However, a stressed crop will metabolize the herbicide more slowly, so increasing herbicide absorption may result in greater crop injury.

Certainly, low spray volumes are not the answer for every herbicide or every spray application situation. For example, NDSU research has shown reduced weed control as spray volume decreased for some contact herbicides such as Flexstar/Reflex or Avenge. But as previously mentioned, applying herbicides in low spray volume may actually result in better herbicide performance compared to high spray volume under certain adverse environmental conditions.

Dr. Brad Ramsdale
NDSU Weed Science, Application Technology
brad_ramsdale@ndsu.nodak.edu


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