Atrazine has been the most widely used herbicide in North American
processing sweet corn for decades; however, increased restrictions in recent
years have reduced or eliminated atrazine use in certain production areas.
The objective of this study was to identify the best stakeholder-derived
weed management alternatives to atrazine in processing sweet corn. In field
trials throughout the major production areas of processing sweet corn,
including three states over 4 yr, 12 atrazine-free weed management
treatments were compared to three standard atrazine-containing treatments
and a weed-free check. Treatments varied with respect to herbicide mode of
action, herbicide application timing, and interrow cultivation. All
treatments included a PRE application of dimethenamid. No single weed
species occurred across all sites; however, weeds observed in two or more
sites included common lambsquarters, giant ragweed, morningglory species,
velvetleaf, and wild-proso millet. Standard treatments containing both
atrazine and mesotrione POST provided the most efficacious weed control
among treatments and resulted in crop yields comparable to the weed-free
check, thus demonstrating the value of atrazine in sweet corn production
systems. Timely interrow cultivation in atrazine-free treatments did not
consistently improve weed control. Only two atrazine-free treatments
consistently resulted in weed control and crop yield comparable to standard
treatments with atrazine POST: treatments with tembotrione POST either with
or without interrow cultivation. Additional atrazine-free treatments with
topramezone applied POST worked well in Oregon where small-seeded weed
species were prevalent. This work demonstrates that certain atrazine-free
weed management systems, based on input from the sweet corn growers and
processors who would adopt this technology, are comparable in performance to
standard atrazine-containing weed management systems.