ISSUE 4   May 31, 2007

WIDEMATCH CROP ROTATION RESTRICTIONS

A Dow supplemental label has been issued to revise the crop rotation tables for WideMatch herbicide. The crop rotation tables on all clopyralid-containing product labels for crops uses have been patterned after the label for Stinger which contains use rates as high as 0.66 pt per acre or 4 oz ae of clopyralid.  The highest labeled rate of WideMatch (1.33 pint per acre) contains only 2 oz ae of clopyralid, with 1.5 oz ae (1 pint per acre of formulated WideMatch) being a more common use rate.

Note the following points:

The rotation tables on the supplemental label will be added to the Section 3 and package label for WideMatch at the next scheduled revision.

The supplemental label containg these revised crop rotation intervals can be found on CDMS or the Dow web site. Refer to R202-004.

 

IS MCPA LABELED ON 1 TO 3-LF WHEAT?

A crop consultant with a proclivity for exactness recently challenged the NDSU Weed Guide’s recommendation of applying MCPA from emergence until prior to boot. The crop consultant looked at several MCPA labels and found the earliest he could apply MCPA was 3-lf and some labels specified after tillering begins. I inherited much of the information in the weed guide when I came to NDSU in 1990 and because MCPA has been registered for so long I have never taken the time to verify the MCPA label application information.

After some investigation I did find the "rest of the story". I contacted John Nalewaja and told him of this discrepancy. He said that the change in the weed guide was a result of research he conducted early in his career. In field studies he attempted to find the rate of MCPA which would injure wheat at various stages. He applied low to high rates of MCPA (up to 2.5 qts/A) to wheat at various stages. He found no injury to wheat from rates as high as 2.5 qt/A even on the small 1-3 lf wheat and the changes were made in the weed guide. Even though this might be viewed as deviation from the label it does not contribute to illegal MCPA residues in the wheat plants because applications would be made earlier than label directions. Data supports the use also.

Through the help of a former AGSCO employee I was notified that the application window of their MXL MCPA label also shows "from application until prior to boot stage". So there are at least one MCPA label that approves use at 1 to 3 lf wheat.

 

SURESTART REGISTERED ON FIELD CORN

SureStart is a new premix being launched by Dow AgroSciences for early season weed control in field corn in programs where the application will be followed with a postemergence application of glyphosate or Liberty. SureStart is a 4.25 lb/gal suspo-emulsion with 3.75 lb/gal acetochlor, 0.12 lb/gal flumetsulam, and 0.29 lb ae/gal clopyralid. You will recognize acetochlor as Surpass and flumetsulam and clopyralid as the ingredients in Hornet. SureStart can be applied preplant, preplant incorporated, preemergence or early postemergence at rates from 1.5 to 2 pt/a. SureStart provides reduced rates compared to standard use rates of Surpass or Hornet (see table). Consequently, weed suppression or control will be less. Still this herbicide should reduce early season competition from a wide range of annual grass and broadleaf weeds. The use precautions for SureStart are very similar to those found on the Surpass and Hornet labels.

 

BREAKFREE LABEL UPDATES

Breakfree is the trade name for the version of acetochlor that DuPont is marketing in corn. Breakfree contains 6.4 lb/gal of acetochlor which is the same concentration as found in Surpass. Atrazine is premixed with acetochlor in the formulations of Breakfree ATZ (3 lb/gal acetochlor + 2.25 lb/gal atrazine) and Breakfree ATZ Lite (4 lb/gal acetochlor + 1.5 lb/gal atrazine). These are the same ratios of acetochlor to atrazine as found in Keystone and Keystone LA from Dow Agrosciences.

 

SELECT MAX LABELED ON PULSE CROPS AND SAFFLOWER

A supplemental Select Max label has been issued for use in field pea, chickpea, lentil, safflower, and many other crops. The rates are similar to use in other broadleaf crops. For field pea, tank mixes with Basagran and Raptor are also labeled. The label can be obtained through CDMS or the Valent web site.

Richard Zollinger
NDSU Extension Weed Specialist
r.zollinger@ndsu.edu


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