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HCS Weed Database

College of Food, Agricultural, and Environmental Sciences


Authority MAXX/XL

Active ingredients: 
sulfentrazone, chlorimuron
Site of action groups: 
14, 2
EPA reg number: 
MAXX 279-3413; XL 279-9560
Restricted use product or combination: 
Rate (per A): 
Authority XL/MAXX application rates on soils with 2 to 4% OM: coarse-textured - 6 to 7 oz; medium-textured - 7 to 8 oz; fine-textured - 8 to 9.6 oz. Authority XL application rate when followed by a POST application of glyphosate in Roundup Ready soybeans or glufosinate in LibertyLink soybeans, on soils with 2 to 4% OM: coarse-textured - 3.2 to 4 oz; medium-textured - 3.2 to 4.8 oz; fine-textured - 4 to 5 oz.
Application timing: 

Preplant or preemergence up to 3 days after planting.  To minimize risk of crop injury, apply a week or more prior to planting. When applied after planting, apply prior to soybean seed germination to reduce injury to emerging soybean seedlings.

Do not apply Authority XL on soils with pH greater than 7.6. Authority XL rates are not pH-dependent, but rotation intervals for all crops except small grains are extended to at least 18 months for soil pH between 7.2 and 7.6, regard- less of rate. Authority MAXX rotation intervals are not pH-dependent.
Rotation intervals: 

Time to wait to plant following application (months; NR = no restrictions) for Authority MAXX/XL: corn - 10; wheat - 4; oats - 12; alfalfa - 12; clover - 18; soybeans - NR; tomatoes - 15/12; popcorn - 10; sweet corn - 18