Earlier this spring, Syngenta announced to customers that it would discontinue the sale of Gramoxone (paraquat)
The announcement states that sales will continue until current supplies run out or until December 31, 2026, whichever comes first. The letter emphasizes that the decision is financial and not related to regulatory or legal actions. Other companies, including AMVAC (Parazone), have also stopped manufacturing and sales.
Alternatives for Paraquat
When considering options for replacing paraquat for burndown applications, group 14 herbicides, such as those listed in Table 1, are viable alternatives. They generally provide rapid control of emerged broadleaf weeds and, in the case of Sharpen and Reviton, some short-term residual activity. Glyphosate should be included in these applications for grass control and susceptible broadleaf species. Glufosinate (Liberty, others) is another nonselective herbicide that could be used in these situations. Combinations of glufosinate with a group 14 herbicide will likely improve control.
Table 1. Herbicides for burndown applications in lieu of paraquat
|
Herbicide (Example)/ Group # |
Rate per acre |
Adjuvant |
Weeds controlled |
|
glufosinate |
34 fl oz/a |
3 lbs AMS/A |
Grasses and broadleaves |
|
carfentrazone |
0.5–1.5 oz/a |
1% v/v COC |
Broadleaves |
|
pyraflufen |
3–4 oz/A (Venue) 0.5–2 oz/A (Vida) |
1–2% v/v COC |
Broadleaves |
|
saflufenacil |
1–2 oz/A |
MSO 1% v/v + AMS (8.5–17lb/100 gal) |
Broadleaves |
|
tiafenacil |
1–3 fl oz/A |
MSO 1% v/v + AMS (8.5–17lb/100 gal) |
Broadleaves + some grasses |
The K-State Chemical Weed Control Guide can help understand where these alternatives for paraquat can be utilized for burndown in crop rotations and crop rotation restrictions. For fallow specifically, Table 2 shows the efficacy ratings on specific weed species.
Table 2. Efficacy ratings for specific weed species.
|
Volunteer Wheat |
Crabgrass |
Foxtail |
Sandbur |
Shattercane |
Kochia |
Marestail/horseweed |
Pigweeds |
Russian thistle |
Field bindweed |
Johnsongrass (established) |
Tumble windmillgrass |
||
|
glufosinate |
Liberty Ultra |
G |
G |
E |
F-G |
G |
F |
F |
G |
F |
F |
F |
- |
|
carfentrazone |
Aim EC |
- |
- |
- |
- |
- |
F-G |
- |
F-G |
F-G |
P |
- |
- |
|
pyraflufen |
Venue, Vida |
- |
- |
- |
- |
- |
G |
P |
P |
G |
F-G |
- |
- |
|
saflufenacil |
Sharpen |
- |
- |
- |
- |
- |
G |
E |
E |
E |
- |
- |
- |
|
tiafenacil |
Reviton |
- |
P |
G |
- |
F |
G |
G |
G |
F |
- |
- |
- |
|
E = Excellent, G = Good, F = Fair, P = Poor, gray boxes = weed not listed on the herbicide label |
|||||||||||||
In addition, Syngenta has announced that FlexstarGT 3.5 sales will be discontinued on June 30, 2026, or until supplies last. FlexstarGT 3.5 is a premix of glyphosate and fomesafen.
Sarah Ganske (Lancaster), Weed Management Specialist
slancaster@ksu.edu
Jeremie Kouame, Weed Scientist – Agricultural Research Center, Hays
jkouame@ksu.edu
Pat Geier, Southwest Research & Extension Center, Garden City
pgeier@ksu.edu
Jeanne Falk Jones, Northwest Area Agronomist
jfalkjones@ksu.edu