Bayer: Increased herbicide use rate helps growers tackle driver weeds

Palmer amaranth and waterhemp are considered by many to be two of the most competitive and aggressive weed species in the United States. David Tanner, product manager at Bayer, said that due to a recent update for the Liberty label, growers will have the opportunity to apply the herbicide to LibertyLink crops at a higher rate in 2018. This application rate increase will help improve control of Palmer amaranth and waterhemp as well as other driver weeds like kochia, ragweed and marestail.

"As weeds like Palmer amaranth and waterhemp get more aggressive, growers must too," Tanner said. "It's absolutely critical to reduce seed production to stop further spread of driver weeds. That's why we've increased our recommended application rates. We want to help corn and soybean growers better control resistant weeds."

Driver weeds can have implications on yield and in long-term weed control plans. For example, according to Take Action, season-long competition by Palmer amaranth at 2.5 plants per foot of row can reduce soybean yields by as much as 79 percenti. A single female Palmer amaranth or waterhemp plant can each produce hundreds of thousands of seeds, allowing them to spread rapidly in short periods of time.

The following table outlines the 2018 recommended herbicide application rates for each LibertyLink crop:

NEW Liberty application rates for 2018
Crop ... NEW 2018 Use Rate (fl oz/A) ... NEW 2018 Max Per Year (fl oz/A)
Soybean ... 32 - 43 ... 87
Field Corn ... 22 - 32 ... 87
Sweet Corn ... 22 ... 44

A successful herbicide program utilizing Liberty should include a comprehensive program of pre-plant options, pre-emergence residual herbicides and Liberty applications in order to be fully effective.

This comprehensive program provides excellent weed control while also reducing the risk or resistance and protecting the long-term sustainability of the Liberty technology. Tanner notes that there is such confidence in Liberty that it comes backed by the Liberty Weed Control Guarantee when used as part of a complete, season long weed control program. To qualify, growers must talk to their retailer and follow local S.T.O.P. Weeds with Liberty guidelines, including:

- Start clean and stay clean: Control weeds prior to planting with a burndown herbicide and continue controlling escapes throughout the season.

- Target weeds at less than three inches tall: Liberty is a contact herbicide and should be applied on less than three-inch weeds that are emerged at time of spraying. Liberty does not offer residual control and therefore will not control weeds that have not emerged.

- Optimize coverage: Growers should use appropriate rates, a minimum of 15 gallons of water and medium to coarse droplet size. Local Bayer representatives can provide recommendations.

- Pair with residuals: Growers must apply labeled rates of pre-residual herbicide with two effective modes of action. Local Bayer representatives can provide local recommendations.

In addition, an adjuvant of ammonium sulfate (AMS) should be used at a rate of 1.5 lb./A to 3.0 lb./A

"We're committed to meeting the ever-changing demands of controlling driver weeds and maintaining customer satisfaction," Tanner said. "We feel these increased rates are one step towards that goal, both for growers today and for growers in the future."

Liberty is a Group 10 herbicide and is the only nonselective herbicide that is effective on these hard-to-control grasses and weeds. It is fast-acting, and results are visual within days of the application. There is no known resistance to Liberty herbicide in U.S. broadacre crops. For more information about Liberty, visit www.cropscience.bayer.us/products/herbicides/liberty.