Counter/Herbicide Interactions in Field Corn (Prostko)

In a previous blog (March 1, 2013), I discussed the potential problems associated with the the use of Counter and certain postemergence herbicides in field corn. The following are some answers to questions you might get asked about this problem at this time of year:

1) Why can't certain herbicides be used after an in-furrow (INFR) application of Counter in field corn?

Organophosphate (OP) insecticides, amino acid synthesis (ALS) and certain pigment (HPPD) inhibitors are metabolized in field corn by the same enzyme system (cytochrome P450 monooxygenase).  When these pesticides are used sequentially (INFR + POST) in field corn, this enzyme system cannot successfully metabolize both active ingredients.

2) How bad would corn yields be affected if this accidentally happened?

Research results from 2012 would suggest that yield losses could exceed 40% if an inappropriate herbicide was used following an INFR application of Counter.

Figure 1.  Corn yield response to the interaction of Counter (INFR) and Steadfast (POST).

3) What herbicides can be applied in field corn if Counter is used INFR?

The following herbicides, commonly used in GA field corn production systems, are safe to use if Counter is applied INFR:

Aim, Atrazine, Clarity, Dual Magnum, glyphosate, Impact, Laudis, Liberty, Prowl, Status, Warrant, 2,4-D, and any pre-mix containing these ingredients.

 

Third Party Indemnified Reflex or Dual Magnum Labels for GA Vegetables (Culpepper)

Agents, I am getting a significant number of calls from growers regarding new Reflex and Dual Magnum vegetable labels.  Consider helping your growers by asking them to come in and visit with you to get their label. This is a great opportunity for young/new agents to obtain face time with our clientele!!

Agents MUST NOT give growers any indemnified label; however, agents can help them through the process but must make sure the grower clicks the “I ACCEPT” liability waver.

Obtaining the label for First Time:

1.  Go to www.farmassist.com

2.  Register the grower (or if you want a label register yourself); “register” is located on the 2nd tool bar in top middle of page.  After filling in information; click I accept at bottom.

: 

3.  The next page that pops up asks about you; you do not have to fill this out if you do not want.

4.  Select products along top bar.

6.  Select indemnified labels (4^th one down).

7.  For state, select Georgia and for product, select Dual Magnum or Reflex (play around and see our other labels) and then submit.

8.  Select the Dual Magnum or Reflex crop of interest and submit.

9.  Accept waiver; this is the process making the label an indemnified label.  GROWER MUST CLICK THE I ACCEPT KEY TO GET THEIR LABEL!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

10.  Print label and have present during application.

New Stuff for Field Corn (Prostko)

Just got word that a couple of new herbicides were registered for use in field corn.  Thought I would give you my take on their potential use in Georgia:

DiFlexx 4SC (Bayer):  DiFlexx is is a mixture of dicamba (DGA salt) and a crop safener (cyprosulfamide).  DiFlexx can be applied POST at 8-16 oz/A from the spike stage through the V6 stage or 36" tall which ever occurs first.  DiFlexx can be tank-mixed with glyphosate or Liberty.  Generally, dicamba is a good broadleaf herbicide but it has not been used very much in GA field corn for whatever reason.  I only have 1 field trial with this product so UGA data is very limited at this point. DiFlexx is not the same formulation of dicamba as the new cotton/soybean formulations (Roundup Xtend, Xtendimax, Engenia).  For a copy of the DiFlexx label, please refer to the following link:

http://www.cdms.net/LDat/ldC4D000.pdf


Revulin Q 51.2WDG (Dupont):  Revulin Q is a mixture of nicosulfuron (14.4%), mesotrione (36.8%), and a crop safener (isoxadifen).   Revulin Q @ 3.4-4 oz/A can be broadcast POST to field corn up to 20" tall or the V6 stage.  It can be tank-mixed with glyphosate, Liberty, or atrazine.  Revulin Q cannot be used if an OP insecticide was used in-furrow.  I have NO GA DATA for this herbicide at this point.  However, Revulin Q may have a good fit in GA since it would have some activity on Texas panicum.  For a copy of the Revulin Q label, please refer to the following link:

http://www.cdms.net/LDat/ldC5D000.pdf

On a different note, I have received several questions about the use of BASF's Sharpen 2.85SC herbicide for burndown use prior to planting field corn.  Here are a couple of things to consider:

1) I have minimal experience with Sharpen thus I do not feel comfortable recommending it.  Thus, neither should you!  I am concerned that some of our south GA soils may be too light.  Obviously, this would be less of a concern in North GA.

2) Sharpen is yet another PPO herbicide (i.e. same MOA as Spartan, Reflex, and Valor).  I have not been recommending PPO herbicides in field corn for obvious reasons. Field corn is the only major row crop grown in GA where a PPO herbicide is not really needed.

3) Some TN and Northern AL growers have been using Sharpen in combination with glyphosate to help control GR-horseweed.

4) 1-2 oz/A of Sharpen will cost somewhere between $5-10/A. For comparison, 1 pt/A of 2,4-D amine costs ~$1.50-2.00/A and 1 qt/A of atrazine costs ~$3.00-3.50/A.

For a copy of the Sharpen label, please refer to the following link:

http://www.cdms.net/LDat/ld99E000.pdf

Herbicide Injury Pictures (Prostko)

If you are looking for a few good resources to help diagnose potential herbicide injury problems, check out the following web-sites:

University of California - Davis (brand new as of January 2015)
http://herbicidesymptoms.ipm.ucanr.edu

Purdue University:
http://www.btny.purdue.edu/extension/weeds/herbinj2/injuryherb1.html

Kansas State University
http://www.ksre.k-state.edu/bookstore/pubs/c715.pdf

University of Missouri
http://weedscience.missouri.edu/herbinjsymptoms/