1. Don Parker, Ph. D. Manager, IPM
Herbicide Resistance
Don Parker, Ph. D.
Manager, IPM

2. Herbicide Resistance Herbicide Resistance is not a new discovery
Herbicide Resistance is not a single crop issue
Herbicide Resistance is not a single state issue
Herbicide Resistance is not a single herbicide issue

3. Herbicide Resistance Management or Stewardship
NCC supports educational efforts to enhance herbicide resistance awareness and appropriate management.
Beltwide Presentations
Cooperative Efforts with Cotton Inc.
NCC Weed Module

5. History Resistant Weeds in Cotton
Goosegrass (Eleusine indica) resistant to dinitroanilines
Reported in 1973 in South Carolina
Trifluralin applied 10 years

6. History Resistant Weeds in Cotton
Common cocklebur (Xanthium strumarium) resistant to organoarsenicals
1988 in South Carolina
MSMA had been applied 15 years

7. Current Resistance Problems in the Cotton Belt
Weed Herbicide Group
johnsongrass fenoxaprop, fluazifop, quizalofop ACCase inhibitors
common cocklebur imazaquin, imazethapyr, chlorimuron ALS inhibitors
kochia chlorsulfuron, sulfometuron, metsulfuron ALS inhibitors
pigweed species chlorimuron, imazethapyr, pyrithiobac ALS inhibitors
Russian thistle chlorsulfuron, sulfometuron ALS inhibitors
goosegrass trifluralin dinitroanilines
johnsongrass pendimethalin dinitroanilines
Palmer amaranth trifluralin dinitroanilines
common ragweed glyphosate glycines
horseweed glyphosate glycines
Palmer amaranth glyphosate glycines
common cocklebur MSMA and DSMA organoarsenicals

8. Remember These
Cultural Control

9. Don't exclusively apply the same herbicide or herbicides with the same mode of action multiple times each year or in successive years
Use mixtures or sequential applications of herbicides with different modes of action that target the problem weed(s)
Rotate crops that allow the use of herbicides with different modes of action
If you choose not to rotate crops, then consider the following:
Adding a residual herbicide
Including herbicides with a different mode of action
Rotating technologies
Planting conventional seed in fields with few weed problems
When herbicide applications are necessary, there are a few key guidelines that will help prevent the development of herbicide resistant weeds. Don't apply the same herbicide or herbicides with the same mode of action multiple times each year or in successive years. Refer to the Herbicide Mode of Action page for more information. Use mixtures or sequential applications of herbicides with different modes of action that target the problem weed(s). Rotate crops that allow the use of herbicides with different modes of action. If you choose not to rotate crops, then you might consider adding a residual herbicide, including herbicides with different modes of action, rotate technologies, or plant conventional seed in fields with few weed problems.

10. National Questions of Stewardship
Glyphosate
66% growers in Indiana indicated low to moderate concern
Only 38% recognize role of repeated MOA’s on selection pressure
90% of MS & NC cotton growers are aware of resistance issues (Lewis et al 2007)
30% are using only glyphosate

11. National Questions of Stewardship
Surcharge to fund stewardship
Adding to Herbicide Labels
Industry only guarantee weed control where stewardship plan is present
Limit sales of traits where market reaches a threshold
Legislative mandates

12. NCC Urges Education and Research
Value of Independent Farm Management Decisions
Difficulties making one glove fit all farms, regions, and tillage practices
Which weighs more, the Jug or the Label?

13. Questions For The Day
How many different modes of action do you use on your farm? Residual Herbicides?
How many fields do you cultivate during the growing season for weed escapes?
How close to your farm must a resistant plant be found before you are concerned enough to change practices?
How many weed spots did you see last year? How many weed spots equals a field?

14. Tomorrow Stewardship preserves use
If you loose the use of your major herbicide on your farm, how much would that loss change your operation? Equipment? Labor?
What alternative weed control would you use?

15. The Race has Started.
Spread the News: Herbicide Stewardship Pays