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Fluroxypyr is Everywhere!

Posted by Drew Lyon | April 29, 2020
Have you noticed that you can’t turn around without bumping into a new herbicide product containing fluroxypyr? Fluroxypyr is a synthetic auxin (Group 4) in the pyridine carboxylic acid family, along with picloram (Tordon 22K) and clopyralid (Stinger). Fluroxypyr was first introduced into the wheat market in Starane herbicide, now sold as Starane Ultra herbicide.

Fluroxypyr’s claim to fame is that it provides excellent control of kochia. It also provides good control of catchweed bedstraw and prickly lettuce. However, it is the ability to control kochia that has thrust it into the limelight and into so many new herbicide products.

Glyphosate-resistant kochia has swept across the Great Plains over the past decade. At the same time, kochia biotypes resistant to dicamba and 2,4-D have also become common in the region. Kochia has become enemy #1 in many parts of the Great Plains where wheat is grown. Consequently, herbicide manufacturers have found it advantageous to add fluroxypyr to a growing list of products.

Fluroxypyr-containing herbicides include:

  • Starane Ultra, Comet, Flurox, Stark Ultra (fluroxypyr)
  • Axial Star (pinoxaden + fluroxypyr)
  • Colt + Salvo and Trump Card (2,4-D + fluroxypyr)
  • Colt + Sword and Voucher (MCPA + fluroxypyr)
  • Colt AS, TruSlate, and WideMatch (clopyralid + fluroxypyr)
  • OpenSky (pyroxsulam + fluroxypyr)
  • Pixxaro EC (halauxifen + fluroxypyr)
  • Sentrallas (thifensulfuron + fluroxypyr)
  • Starane Flex (florasulam + fluroxypyr)
  • Starane NXT (bromoxynil + fluroxypyr)
  • Batalium (bromoxynil + flucarbazone + fluroxypyr)
  • Carnivore and Cleansweep M (bromoxynil + MCPA + fluroxypyr)
  • Boomer, Full Deck, Hat Trick Three Way, TruSlate Pro, and Weld (clopyralid + MCPA + fluroxypyr)
  • Cleansweep D and Kochiavore (2,4-D + bromoxynil + fluroxypyr)
  • Goldsky (florasulam + pyroxsulam + fluroxypyr)
  • PerfetcMatch (clopyralid + pyroxsulam + fluroxypyr)
  • Scorch (2,4-D + dicamba + fluroxypyr)
  • Supremacy (thifensulfuron + tribenuron + fluroxypyr)
  • Travallas (metsulfuron + thifensulfuron + fluroxypyr)

The strategy of adding fluroxypyr to so many different products seems somewhat flawed to me. While mixing two active ingredients with different mechanisms of action effective on a specific troublesome weed species is a good practice for minimizing the risk of developing herbicide resistance, relying too much on one active ingredient seems doomed to failure. Many of the active ingredients to which fluroxypyr is being added are not particularly effective on kochia. Numerous kochia biotypes are now resistant to the ALS-inhibiting herbicides such as metsulfuron, thifensulfuron, tribenuron, and florasulam. Clopyralid and MCPA are not particularly effective on kochia. Bromoxynil can provide effective control of kochia when it is small, but is less effective when applied to larger plants. All of this is to say that many of these new herbicide products do not contain the best mixes for kochia control. So the question has to be asked: why mix fluroxypyr with them? Spraying fluroxypyr everywhere is not a good way to steward this active ingredient.

In the PNW, kochia is not the widespread problem it is in the Great Plains, so many of these herbicide combinations make even less sense here in Eastern Washington. It is my contention that fluroxypyr should only be used as an individual active ingredient product for the control of kochia, catchweed bedstraw, or prickly lettuce. Fluroxypyr should always be tank mixed with an herbicide that is also effective on the weed or weeds of concern. Visit the Winter Wheat Herbicide Efficacy Tables to see what herbicides are effective on various weeds.

Do you agree? If not, please tell us why you don’t agree.

4 thoughts on "Fluroxypyr is Everywhere!"

  1. Douglas Johnson says:

    This is helpful info to think about.
    If you have significant bedstraw, which would 60% of the fields I consult on, and you want to plant lentils it is either Starane or Huskie. It the weather is cloudy then Starane is the only option, so I do find it necessary in many tankmixes in PNW.
    Thanks for the post!

    1. Drew Lyon says:

      I agree that fluroxypyr is very useful for the control of catchweed bedstraw. I would encourage tank mixing it with another herbicide effective on bedstraw such as Orion (MCPA + florasulam) or using Starane Flex (fluroxypyr + florasulam). I would also encourage trying to rotate the use of Starane (fluroxypyr) with Huskie (pyrasulfotole + bromoxynil). Planting dry pea or chickpea instead of lentil after wheat would allow the use of other products effective for the control of catchweed bedstraw, such as Quelex (halauxifen + florasulam) or Talinor (bicyclopyrone + bromoxynil).

      As much as anything, the purpose of my post was to make growers aware of the large number of products that contain fluroxypyr so that they have a better sense of how much they may be unknowingly using. Some growers may not be aware that they have used fluroxypyr for years and then wonder why it does not work when they need to control catchweed bedstraw, prickly lettuce, or kochia.

  2. Dean Walker says:

    Don’t disagree at all to your comments. We’ve used and abused the Group 4 chemistry for a long time with so far minimal resistance. I think the tendency is to play the short game and go with the popular mixes because the products that are a single AI that are more flexible are actually more expensive and you end up paying to get a particular AI out of a mix.

    1. Drew Lyon says:

      I agree. Manufacturers are partly to blame for the problem because they use pricing to lock growers into using the premixes even where they don’t make sense. Some manufacturers also use premixes to extend patent life on products with little regard given to the management of herbicide resistance. I hope my post raises awareness of just how many products contain fluroxypyr so that growers can do a better job of avoiding frequent or excessive use of this one active ingredient.

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