Running Down the Clock with
Post-emergence Timing Flexibility
Many weeds overwinter in soils, giving them a clear advantage
n the spring when soybean growers plant their fields. All it takes
for weeds to germinate is a spurt of mild weather and some rain,
and before a grower knows it, his field is flush with a rich, green
carpet of weeds. But attacking weeds before they reach this stage
is crucial for a successful weed management program.
Many variables impact herbicide application timing, including planting date, soil temperature, and
amount of rainfall that occurs both before and after planting. Pre-emergence herbicides that offer
long-lasting residual control are a critical step in weed management. By applying a preemergence herbicide, growers are free from the worry that can be caused by delayed planting
due to unforeseen and uncontrollable circumstances. According to Iowa State University
Extension, a pre-emergence residual herbicide enables better time management during
condensed planting windows and offers increased flexibility for post-emergent herbicide
applications. By utilizing both pre- and post-emergence treatments, growers ensure overlapping
coverage that keeps fields protected season long.
According to The Ohio State University, pre-emergence herbicides work especially well for fastgrowing weeds, such as ragweed, that may emerge much earlier and develop more quickly than
other weed species. While it may seem more economical to delay treatment in favor of making
fewer trips across the field to save on up-front application costs, valuable yield is lost as those
early-emerging weeds compete with soybean seedlings for soil space, water and nutrients.
According to Mike Owen at Iowa State University, a clean field at the end of the season does not
necessarily mean that the weed management program was successful. Glyphosate-based
programs applied later in the season may provide adequate weed control when viewed in
September. However, yield monitors will tell a much different story. The objective of using
herbicides is to protect soybean yield, not to control weeds, says Owen. A pre-emergence
herbicide with lasting residual can protect fields from weeds for weeks after an application;
thereby, still allowing for later application of a post-emergence herbicide without forfeiting any
yield from weeds that would have otherwise already emerged.
Syngenta Solution
As shown in the research below, growers can receive yield benefits from using Prefix® herbicide
as a pre-emergence treatment, regardless of the glyphosate application timing. Prefix allows a
wider application window in glyphosate-tolerant (GT) soybeans, thus reducing the risks
associated with applying glyphosate too early or too late, and provides a profitable return per
acre.
Prefix, a Resistance Fighter™ brand, enables growers to target difficult-to-control weeds that
have developed or are likely to develop herbicide resistance in GT soybeans, while maximizing
yield and profit potential. Prefix contains two proven active ingredients, S-metolachlor and
fomesafen, that protect yields by controlling highly competitive grass and broadleaf weeds. Prefix
allows substantial timing flexibility for a post-emergence glyphosate application, such as
Touchdown Total® herbicide, and improves the efficacy of these applications.
Together, Prefix and Touchdown Total contain three different
herbicide modes of action that, when combined with cultural
practices such as crop rotation and tillage, help growers reduce
the weed seed bank, maximize weed control diversity and
fight herbicide resistance.
For all of the latest soybean news from Syngenta,
visit http://Soybeans.FarmAssist.com, the one-stop location for everything soybeans. And don’t
forget to register for the Soybean Insider to be delivered directly to your email at
www.FarmAssist.com/SoyInsider. Follow Syngenta on Twitter or Facebook.
For more information, visit www.Prefix-Herbicide.com or call the Syngenta Customer Center at 1866-SYNGENT(A) (796-4368).
©2012 Syngenta. Important: Always read and follow all bag tag and label instructions
before buying or using Syngenta products. The instructions contain important conditions
of sale, including limitations of warranty and remedy. All products may not be registered
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