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HCS Weed Database

College of Food, Agricultural, and Environmental Sciences


Authority First/Sonic

Active ingredients: 
sulfentrazone, cloransulam
Site of action groups: 
14, 2
FMC, Dow AgroSciences
EPA reg number: 
Authority First 279-3246, Sonic 61779-680
Restricted use product or combination: 
Rate (per A): 
Can be applied at rates as low as 3 oz/A in Roundup Ready soybeans, when followed with a postemergence glyphosate application. Use rates in non-Roundup Ready soybeans: 3% or less OM - 6.5 oz; greater than 3% OM - 8 oz.
Application timing: 

Preplant or preemergence. Apply preplant or preemergence, up to 3 days after soybean planting. To minimize risk of crop injury, apply a week or more prior to planting.

Rotation intervals: 
Time to wait to plant following application (months; NR = no restrictions): corn - 10; wheat - 4; oats - 12; alfalfa - 12; clover - 30+bioassay; soybeans - NR; tomatoes - 30+bioassay; popcorn - 10; sweet corn - 10. Corn recrop extends to 18 months for soils with both of these: less than 1.5% OM and pH greater than 7.