Technical Abstract: Oklahoma producers are interested in sweet onion (Allium cepa L.) as an alternative crop for farm diversification, but weed control continues to be a primary obstacle. The weed control challenges for onion production are even greater for those considering organic crop production. The few organic herbicides cleared for organic vegetable production are mainly non-selective, contact herbicides. Research was conducted at Lane, OK, to determine the impact of broadcast applications of acetic acid on broadleaf weed control. 'Candy' and 'Cimarron' onions were transplanted on March 13, 2007. The experiment included 6 weed control treatments (2 application volumes, 2 hand weeding levels, plus an untreated weedy-check and an untreated weed-free) with 4 replications. Nutsedge and grass weeds were selectively removed to investigate the impact of the acetic acid on the broadleaf weeds. Vinegar (20% acetic acid) was applied as an over-the-top broadcast application at 50 or 100 gpa on April 21, 2007 using four 8002 nozzles on 20 inch spacing. Within each application volume (50 and 100 gpa) plots were either handweeded or the uncontrolled weeds were allowed to grow. Weed control ratings were collected throughout the growing season. Weed control peaked at 7 DAT, averaging 95% and 99% total broadleaf weed control for the 50 and 100 gpa application volumes.