Greensboro N.C. - As corn and soybean growers deal with an expanding and intensifying threat of resistant weeds, Syngenta is recommending strategies for managing weeds that begin early in the season.
“Pigweeds have greatly affected our herbicide choices,” said Philip Nelson, a corn grower in Windom, Kansas. “In fact, we now apply herbicides ahead of time to keep the weeds from growing. It’s getting really hard to kill a pigweed at any stage of growth, but you can still kill the sprout and keep it from becoming a problem.”
As growers adopt more sustainable tillage programs and weed resistance to different modes of action expands, the importance of applying the right herbicide at the right time can't be overstated. Overusing the same herbicides without a programmed approach can lead to resistance.
“It’s important for growers to always monitor their weed-management practices, because subtle weed escapes in a field can be a signal that there may be resistant weeds emerging,” said Dane Bowers, Syngenta herbicide technical product lead.
According to Bowers, if growers notice weeds surviving in fields, even in small numbers, they should consider changes in their management plan to help stop resistance in its tracks.
“We have been on a herbicide resistance merry-go-round,” Bowers said. “We hop on one horse, or chemistry, and ride it until we wear it out, then we select another horse for the next ride. It is time to step off the merry-go-round and develop resistance-management strategies.”
To avoid getting caught in a cycle of resistance, growers can turn to pre-emergence applications of powerhouse combination technologies, like Acuron® and Acuron® Flexi herbicides for corn and BroadAxe® XC and Boundary® 6.5 EC herbicides for soybeans. These herbicides contain multiple effective modes of action and active ingredients that work together to control tough weeds before they emerge.
“Using tank-mix partners or premixes with multiple effective modes of action in each application during the growing season can help reduce the selection pressure caused by using a single mode,” said Bowers, who also encourages growers to use residual herbicides whenever possible to help keep their fields clean all season long.
Syngenta has developed Resistance Fighter® to help growers effectively manage resistant weeds through education, local recommendations and a strong portfolio of herbicides. Syngenta also recommends the following strategies to fight weed resistance:
- Start with clean fields. Help control emerged weeds before planting by applying a burndown herbicide plus a pre-emergence residual herbicide.
- Employ crop rotation. This practice will extend the range of available herbicides and agronomic practices.
- Rotate herbicide-tolerant traits. Alternate herbicide-tolerant traits or use herbicidetolerant trait stacks for more efficient rotation. This approach enables growers to rotate their herbicide applications and reduce selection pressure on resistant biotypes.
- Always apply herbicides at the full, labeled rate and correct growth stage. This ensures the most effective control of weeds in fields.
- Prevent weed escapes from producing seed. Consider spot herbicide applications, hand removal of weeds or other techniques to stop weed-seed production.
- Do not tolerate any weeds in the soil bank. Not allowing surviving weeds to set seed will help decrease annual weed populations and prevent major weed shifts.
- Clean equipment. Always clean tillage, seeding and harvest equipment when leaving fields that are infested with herbicide-resistant weeds.
- Utilize good agronomic practices. Consider narrow rows, increased plant populations and other practices that promote crop growth and competitive ability.
To learn more about weed-resistance management and other issues impacting agriculture, go to www.SyngentaThrive.com. Join the conversation online – connect with us at social.SyngentaUS.com.
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