Herbicide Options for Double-Cropped Soybeans

With the current high price of soybeans, many GA growers are planting soybeans after field corn.  Thus, I have received many questions about weed control options for this situation.  Please consider the following:

1) My recommendations for weed control at this point in time are very different from early/normal planted soybeans. 
2) My primary concern is crop rotation.  If wheat is to be planted this fall or field corn is to be planted next spring, herbicide options may be limited depending upon the application date.
3) Table 1 lists the current labeled crop rotation restrictions for common soybean herbicides.
4) In order to prevent any major crop rotation problems, I would suggest a PRE application of Dual Magnum (or generic) followed by an EPOST application of glyphosate + Cobra or Ultra Blazer (RR soybeans).
5) Valor would be an excellent choice in fields where a POST application of Cobra, Prefix, Reflex, and Ultra Blazer may not be needed.  If we are going to protect Valor, growers must avoid PRE applications of Valor followed by POST applications of Cobra/Prefix/Reflex/Ultra Blazer. PPO abuse for sure!
6) If field corn will be planted next spring (~8 months), avoid the use of Canopy, Envive, Prefix, Pursuit, and Reflex.

Reflex Carryover to Field Corn in Georgia (Prostko)

Last few days, I have gotten several questions about potential Reflex carryover to field corn in Georgia.  Here are a few of my thoughts:

1) The labeled rotation restriction for field corn following Reflex is 10 months.
2) Average field half-life for Reflex is 100 days.  It is probably much shorter in our soils.
3)  I have only seen Reflex carryover injury to field corn on the farm 1 time in Georgia.  This occurred in Early Co. in a field that received 3 applications of Reflex in cotton the prior year.
4) Most of the weird symptoms that are occurring in Georgia corn fields at this time are not likely caused by Reflex (i.e. assuming excessive rates or delayed applications were not made). 
5) My colleagues in Tennessee and Arkansas have been reporting some problems with Reflex carryover to field corn but you must remember that these states have heavier soils with higher organic matter contents than Georgia.  
5) The following are some pictures of known Reflex injury to field corn. 

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Leadoff Herbicide (Prostko)

The UGA Weed Science Group has been getting many questions from County Agents regarding DuPont’s new burndown herbicide Leadoff.  Here is what we know and do not know:

1)   Leadoff 33.4WSG is a mixture of Matrix/Resolve (rimsulfuron – 16.7%) + Harmony (thifensulfuron -16.7%).

2)   The typical use rate for Leadoff is 1.5 oz/A at a cost somewhere between $7-8/A

3)   Rotation restrictions for common GA row crops are as follows:  soybean/cotton = 30 days; corn = anytime; peanut = 45 days.

4)   Leadoff is being aggressively promoted by DuPont sales reps as a residual alternative for the control or Palmer amaranth. 

5)   There has been no research conducted by the UGA Weed Science Group to support or refute these claims. 

6)   Rimsulfuron does provide some soil residual activity on certain weeds.  However, I can find no published data for Palmer amaranth.

7)   The current Leadoff label suggests that it will only provide partial control or suppression of Palmer amaranth.   http://www.cdms.net/LDat/ld2AA003.pdf

8)   I am not sure why would any grower would want only partial control or suppression of Palmer amaranth with Leadoff when other residual herbicides are available that have a proven record of control (i.e. Atrazine, Valor, Dual Magnum, Direx).

9)  A few field trials will be conducted by the UGA Weed Science Group this year to figure out what kind of residual control Leadoff actually provides. 

What's That Weed (Prostko)

Recently while walking through a fallow field near my home in Tift Co., I came across this weed.  At first glance, you might say it is shepherd’s purse (Capsella bursa-pastoris).  However, the common name for this plant is pinnate tansy mustard (Descurainia pinnata).  Pinnate tansy mustard is a spring/winter annual member of the Brassicaceae or Mustard family of plants.  As far as I can tell from the literature, it should not be any more difficult to control than wild radish or other common members of this family.

Capreno Herbicide (Prostko)

Recently, I have been getting a few questions about Bayer's new corn herbicide, Capreno.  I have conducted numerous field trials with Capreno over the last several years.  Consequently, Capreno is now listed in the 2012 UGA Pest Control Handbook (page 52).  A few general thoughts about Capreno:  1) I would always recommend tank-mixing atrazine with Capreno; 2) Capreno + Atrazine should be good on most of our common weed species including pigweed and Texas millet; 3) I have no clue what Capreno will do on tropical spiderwort/Bengahl dayflower?  The following are a few slides with additional information about Capreno: