Scythe® and Roundup® Pro

Scythe® Herbicide has become widely recognized as an excellent tank-mix partner for Roundup. Even though Scythe is a contact herbicide that provides extremely rapid and non-selective burn-down, it synergizes the systemic, root killing activity of Roundup. The same advantages of this tank mix continue to be seen with the new formulation, Roundup Pro, and there is no barrier to using these two herbicides together in a tank mix.

In selected markets, Roundup is being replaced by a new formulation of glyphosate called Roundup Pro. This new formulation contains an optimized surfactant system which makes it unnecessary to add surfactant adjuvants as had become common practice with the previous formulation. Because the Roundup Pro label states that no adjuvants should be added, questions have arisen about the combination of Roundup Pro with Scythe. There has also been confusion about whether Roundup Pro contains the active ingredient of Scythe, pelargonic acid. These questions can be answered as follows:

• Scythe is not an adjuvant, it is a registered herbicide. The exclusion of adjuvants on the Roundup label does not apply to Scythe.

• Roundup-Pro works just as well in the Scythe tank mix as Roundup.

• Scythe synergizes glyphosate through a mechanism which is completely different from the way that surfactants enhance glyphosate activity. Both surfactants and Scythe can increase glyphosate activity at the same time.

• Scythe tank mixes produce burn-down much faster than Roundup Pro. At high gallonage Scythe/Roundup Pro mixtures give weed control within hours while Roundup Pro alone shows plant damage only after many days. (See data on the following page).

• Roundup Pro does not contain the active ingredient of Scythe, pelargonic acid.

• Mycogen Corporation holds a patent for the combination of pelargonic acid and glyphosate (US patent # 5,196,044).

Example Data:

Herbicides and tank mixes were applied to greenhouse grown weeds at 75 GPA and held at 60-80F. Scythe was used at 3% v/v in tank mixes with 1 qt/acre rates of Roundup or Roundup Pro and compared with those glyphosate formulations applied alone.

This bulletin contains new or supplemental instructions for the use of this product which may not appear on the package label. Mycogen provides this use information in accordance with Section 2(ee) of FIFRA.

Scythe is a registered trademark of Mycogen Corporation. Roundup is a registered trademark of Monsanto Corporation.

Scythe EPA Reg. No. 53219-7 MYC. JJ#2209 2/96