Cull Onion Disposal Deadline, March 15

Tuesday March 14, 2023

Boise, Idaho – March 15, 2023 is the deadline for disposal of cull onions in Ada, Canyon, Gem, Payette, Owyhee and Washington counties.

According to the “Rules Governing the Disposal of Cull Onions and Potatoes,” all cull or waste onions not useable for human consumption, will be disposed of by an approved method prior to March 15 each year to protect the onion industry from onion maggot. Onions sorted after March 15 must be properly disposed of within one week.

“The regulations are aimed to reduce the potential for damage of onion crop in the largest onion production region in the U.S.,” said Andrea Thompson, ISDA Plant Industries Section Manager. “We have received excellent cooperation from the onion industry and look forward to continuing this effective program.”

ISDA inspectors will be monitoring disposal sites to verify that culls are being properly disposed of. Options for proper disposal under the rule include pit burial, feeding, composting, spreading, chopping and shredding. The University of Idaho’s “Best Management Practices for Pit Disposal of Cull Onions (Publication CIS 1064) is referenced in the rules and available through University of Idaho Extension.

Onion maggot is an aggressive pest that reproduces quickly. The larval stage of the onion maggot attacks and destroys germinating seedlings by feeding on roots. Later generations feed on expanding bulbs which could further devastate onion yields. Feeding damage also provides an avenue for pathogens to rot bulbs during storage. Without these restrictions, insect damage could cause growers to lose more than 50% of their yield.

The “Rules Governing the Disposal of Cull Onions and Potatoes” and other cull onion disposal information can be found at

Contact: Andrea Thompson

Phone: (208) 332-8620