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Authority Assist (3.33 lb ai sulfentrazone + 0.67 lb ai imazethapyr) - FMC
Table 1. Authority Assist rate structure
 
Percent Organic Matter
Soil Texture
1% to 2%
2% to 4%
 
-------------------------- fl oz/A --------------------------
Coarse[1]
6 to 8 [4]2
8 to 10 [4 to 5]
Medium
8 to 10 [4 to 5]
10 to 12 [5 to 6]
Fine
10 to 12 [5 to 6]
12 [6]
Use higher rates for soils with pH less than 7 and lower rates for pH greater than 7 within the rate structure.
[1]Do not use on sand with less than 1% organic matter.
[2]A reduced rate structure is provided to be used in the fall, preplant, and preemergence in a Roundup Ready soybean system.
[Labeled in Indiana] Last year we mentioned Authority Assist, a premix of Authority and Pursuit, but at that time it was not labeled. Authority Assist is now labeled for preemergence use in soybean. It can be applied from 45 days before planting to 3 days after planting. To avoid the potential of seedling injury do not apply at cracking. Rates are from 6 to 12 floz/A depending on soil texture and percent organic matter (table 1). The sulfentrazone component has shown excellent preemergence control of pigweed, lambsquarter, morningglory and good control
on annual smartweeds and black nightshade. The addition of imazethapyr will increase control on velvetleaf and foxtail.
       
Updated 1/8/09

Information listed here is based on research and outreach extension programming at Purdue University and elsewhere.
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Authority Assist