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.