As we continue to battle herbicide-resistant weeds, especially in the pigweed species, it is important to use multiple herbicides with different modes of action, as well as to rotate modes of action in an effective herbicide resistance management plan. One mode of action with limited weed resistance is Group 10 – glufosinate, otherwise known as Liberty® herbicide.
Come to the ILSoyAdvisor field days in August (2nd in Hinckley, 3rd in Seymour, 4th in Benton) as Bayer CropScience reviews the importance of managing Liberty’s use by applying at the right weed height, volume and spray pressure to optimize its efficacy. To register for an event, click here.
Tips for managing Liberty herbicide:
- Coverage – Liberty is a contact herbicide. It provides the best control using nozzles and pressure that generate medium-size droplets (250 – 350 microns). If droplet sizes are in this range, then 15 gallons per acre of carrier is adequate, unless you have very high weed density. Under higher weed density it would be prudent to increase to 20 GPA of water carrier.
- Adjuvants – Liberty contains a built-in adjuvant system. The only additional product that MUST BE added to the tank for Liberty herbicide to effectively control weeds is ammonium sulfate (AMS). Never add COC or MSO to Liberty herbicide or crop response could occur.
- Tank mix partners – Many soybean herbicides can be tank mixed with Liberty herbicide. It doesn’t provide residual control of weeds; therefore, a residual tank mix partner could be warranted.
- Timing – Liberty is labelled on soybeans from emergence to bloom. Apply to weeds that are less than 6-inches tall. Some weed species may show reduced control with late evening applications, including velvetleaf and lambsquarters.
- Rate – Apply 29 – 36 oz per acre with 2 – 3 lbs. AMS per acre. Maximum single application is 36 oz per acre. Maximum per growing season is 65 oz per acre.
- Mixing – First fill the spray tank ½ full of water, agitate, add AMS, add tank-mix partner, complete filling of tank with water then add the Liberty herbicide. If foaming occurs, add silicone-based anti-foam agent.
- Rainfast – Liberty is rainfast in 4 hours.
- Pre-harvest Interval of Liberty is 70 days.
- Off target concerns – As it is primarily a contact herbicide, off target concerns are not as large of a concern with Liberty herbicide as some other translocated products.
Liberty herbicide is an important part of a good weed resistance management plan because it has very few resistant weeds (none that have been identified in row crops) and has a different mode of action than other herbicides. For an effective weed resistance management plan, Bayer CropScience recommends using a full rate pre-emergence residual herbicide, then coming back to spray 3- to 4-inch-tall weeds with 29 – 36 oz of Liberty herbicide and 2 – 3 lbs. AMS. Depending on what modes of action were in the pre-emergence product, this should deploy 3 – 4 herbicide modes of action.