Cull Onion Disposal Deadline Approaching

Monday March 12, 2018

The Idaho State Department of Agriculture (ISDA) issued a reminder today that Idaho’s cull onion disposal deadline is March 15.

The deadline is set in Idaho rule and applies to Ada, Canyon, Gem, Payette, Owyhee and Washington counties. Culls are onions deemed to be waste or to be unsuitable for human consumption. No culls may be on hand at any packing sheds, in fields or at animal feed facilities on the morning of March 15.

Onions sorted after the cull deadline must be properly disposed of within one week. Trucks transporting onions should be covered to prevent spills along roadsides. A civil penalty of up to $10,000 may be enforced for each violation.

Options for proper disposal under the rule include pit burial, feeding and composting.

“The deadline is aimed at reducing the potential for damage to Idaho’s onion crop because onion maggot, a destructive pest, is frequently found in cull onion piles,” said Jared Stuart, Agricultural Section Manager for the ISDA’s Division of Plant Industries. “The larval stage of the onion maggot attacks and destroys portions of the onion bulb, providing an avenue for fungi and bacteria to cause bulbs to rot during storage. With the right conditions, the insect can potentially destroy 80 percent to 90 percent of the crop.”

Adult onion maggot flies emerge in April and May and are attracted to the distinctive odors given off by sprouting onions and new seedlings. Each onion maggot can destroy up to two dozen seedlings during its two-week lifespan, so crop damage can be substantial. If not properly disposed of, culls serve as breeding and egg-laying sites for the adult flies.

Several resources are available for more information on the deadline and appropriate disposal methods:

  • ISDA’s website,,
  • The University of Idaho’s “Best Management Practices for Pit Disposal of Cull Onions” (publication CIS 1064), and
  • The ISDA publication, “Cull Onion Disposal in Idaho.”


March 12, 2018

Contact: Jared Stuart

Office: (208) 332-8620

ISDA Main: (208) 332-8500