Many factors contribute to weeds developing resistance to herbicides. One common problem is applying herbicides at the wrong timing. To help growers, Syngenta is providing key insights into herbicide resistance management as well as optimal application timing.<\/p>\n
\u201cThe key to preventing herbicide-resistance development is growers\u2019 weed-management practices,\u201d said Joe Wuerffel, Ph.D., research and development scientist at Syngenta. \u201cApplying both pre- and post-emergence herbicides at the right time is one basic step growers can take in their management plans to give all of us a leg up on tough-to-control weeds.\u201d<\/p>\n
Spray close to planting<\/p>\n
It\u2019s important with pre-emergence herbicide applications to spray as close to planting as possible. This will help get the most out of pre-emergence herbicides as well as achieve the longest residual activity.It\u2019s also important to use a herbicide that will perform on each grower\u2019s schedule.
\n\u201cMother Nature can throw a wrench into any planning,\u201d said Wuerffel. \u201cThat\u2019s why I recommend growers use a highly flexible herbicide that will maintain its effectiveness, whether you have to move up your applications weeks before planting or delay your application until your crops have already emerged.\u201d<\/p>\n
Don\u2019t let weeds grow
\nFor post-emergence applications, Wuerffel said it is crucial to consider weed height. Syngenta recommends growers spray weeds based on heights recommended on the label. For most weeds that\u2019s before weeds reach 4 inches.<\/p>\n
\u201cWhen the label says spray before weeds are 4 inches, that\u2019s for the tallest weed in your field,\u201d he explained. \u201cIf you wait for an average height of 4 inches, but your tallest weed is 8 inches, you are essentially using a reduced rate application for most or part of your field.\u201d<\/p>\n
Wuerffel says spraying weeds when they\u2019re too tall can lead to resistance development.<\/p>\n
\u201cThis can lead to weed escapes, which will then lead to those weeds producing seed,\u201d said Wuerffel. \u201cThe weeds that were exposed to a herbicide, but not killed by it, may be passing on herbicide resistance traits to the next generation.\u201d<\/p>\n
Plan post-emergence applications<\/p>\n
He recommends growers plan a time for their post-emergence application with an overlapping residual, usually three to four weeks after the pre-emergence application, regardless of whether there are any weeds present in the field.<\/p>\n
\u201cMark your calendar or set a reminder on your cell phone. Don\u2019t wait until you see that you need it, because oftentimes that\u2019s already too late,\u201d said Wuerffel. \u201cAlso, follow weather forecasts closely for anything that could delay timely herbicide applications. Being proactive in planning your post-emergence application can help you plan around those curveballs.\u201d<\/p>\n
The global Herbicide Resistance Action Committee agrees. In their best management practices guide, they say the more weeds present in the field when the herbicide is applied, the higher the chance that resistance will develop.<\/p>\n
Best application practices<\/p>\n
Wuerffel says growers\u2019 best option is to use a two-pass system of overlapping residual products with multiple effective sites of action.<\/p>\n
\u201cIf you\u2019re looking for performance, application flexibility and maximum yield protection, Acuron\u00ae herbicide is your best choice for weed management in corn,\u201d he said. \u201cIt contains four active ingredients, including the unique component bicyclopyrone, and three effective sites of action for the most effective and consistent control of tough weeds, including resistant weeds.\u201d<\/p>\n
Acuron can be applied in a split-shot application with a portion of the rate applied pre-emergence, followed by the remainder of the rate applied post-emergence for overlapping residual control.<\/p>\n
It is also highly flexible, with the ability to be applied up to 28 days before planting or until corn has reached 12 inches in height.<\/p>\n
\u201cFor soybeans, I tell growers to start off with a pre-emergence application of Boundary\u00ae 6.5 EC, BroadAxe\u00ae XC or Prefix\u00ae herbicide,\u201d he said. \u201cBoundary 6.5 EC and BroadAxe XC can be followed by Flexstar\u00ae GT 3.5 herbicide as a post-emergence application for multiple effective sites of action.\u201d
\nWuerffel notes that Boundary 6.5 EC can also be followed by Prefix as an early post-emergence herbicide.<\/p>\n
Learn more about the best time to apply herbicides in this video with Wuerffel.<\/p>\n
For more information about how to fight weed resistance, visit ResistanceFighter.com. Join the conversation online \u2013 connect with us at Syngenta-US.com\/social.<\/p>\n
Source: Syngenta USA<\/p>\n","protected":false},"excerpt":{"rendered":"