Fierce Labeled for Use in Soybean (Prostko)

Fierce 76WG recently received a label for preemergence (PRE) use in soybean.  Fierce 76WG is a combination of 33.5% Valor (flumioxazin) + 42.5% Zidua (pyroxasulfone).  The normal use rate of Fierce for coarse soil types is 3 oz/A.  Fierce 76WG @ 3 oz/A is equivalent to Valor 51WG @ 2 oz/A + Zidua 85WG @ 1.5 oz/A.  Generally, Fierce has looked impressive in my field trials (Figure 1).  A copy of the supplemental Fierce soybean label can be found at the following location:
http://www.valent.com/Data/Labels/2013-FIE-0013%20Fierce%20Soybean.pdf

Figure 1.  Fierce for Weed Control in Soybean - 2012

Currently, there are several PRE soybean herbicides that contain the active ingredient flumioxazin (Envive, Fierce, Valor, Valor XLT).  There is no question that one of the most effective herbicide programs for the control of Palmer amaranth in soybean would be to use one of these flumioxazin-containing products (PRE) then follow with Reflex (POST).  However, this progam should not be encouraged since all of these herbicides have the same mode of action (PPO-inhibitor).  Growers in a soybean/corn rotation might get away with this program since Reflex and Valor are not being overused.  But, growers in a cotton/peanut rotation, who are relying heavily on Valor and Reflex, should avoid their overuse in soybean.  Some specific recommendation's for soybean growers who want to protect Valor and Reflex are presented in Figure 2. 

Figure 2.  Soybean Herbicide Options That Help Protect Valor and Reflex



Counter/Herbicide Interactions in Field Corn (Prostko)

It is very important to remember that if a field corn grower wants/needs to use an in-furrow application of Counter 20G, he cannot use certain herbicides (Figure 1).  This negative insecticide/herbicide interaction is more commonly associated with the ALS-inhibiting herbicides (Accent, Beacon, Steadfast Q) but can also occur with certain HPPD-inhibitors (Callisto, Halex GT) and PPO-inhibitors (Sharpen, Verdict).  In one of my field corn trials conducted in 2012, a Counter/Steadfast interaction resulted in a 40% yield loss.  The manufacturers of Counter 20G (AMVAC) have put together a excellent publication to address this issue (Figure 2).  

Figure 1.  Field Corn Injury Caused By Counter/ALS Herbicide Interaction.

 



Figure 2.  AMVAC Counter/Herbicide Publication