Amendments made to prevent maggot infestation in Malheur County onions
By Logan Bagett on Tuesday, April 7th, 2026 in More Top Stories Northeastern Oregon News
ONTARIO – (Press Release from the Oregon Department of Agriculture)
On Friday, the Oregon Department of Agriculture (ODA) filed emergency rules with the Oregon Secretary of State’s office, temporarily amending Oregon Administrative Rule (OAR) 603-052-0360 that protects Malheur County, and its onion industry, from Onion Maggot infestation. This pest can cause severe yield losses and significant financial harm to the onion industry.
Severe July and August thunderstorms caused widespread bacterial rot in the 2025-2026 onion crop, resulting in about 700-800 million pounds of cull onions needing disposal. Disposal options are limited, as county burial and solid waste capacity are already strained. Cull onions are byproducts rejected due to size or quality.
OAR 603-052-0360 requires onion cull piles in Malheur County to be disposed of or buried under at least 12 inches of onion-free soil by March 15 each year. Without this change, growers and shippers would not be able to lawfully and feasibly dispose of large volumes of cull onions in a timely manner.
The temporary amendments will provide immediate relief to growers by:
- Removing the numerical limit for chopped or shredded onion plant debris returned to fields and worked into the soil, while maintaining the requirement for it to be used at agronomic rates.
- Updating the reference for insecticide use under Section F. Growers may now use insecticides applied in accordance with label instructions at prescribed intervals until proper disposal occurs. This ensures access to the best available chemical treatment options when weather prevents disposal.
The ODA Pesticides Program has identified the following EPA-labeled insecticides that can be applied legally to onion cull piles for onion maggot control:
- EPA Reg. No. 70299-17, AzaGuard (BioSafe Systems, a.i. azadirachtin)
- EPA Reg. No. 5481-559, Ecozin Plus 1.2% ME (AMVAC, a.i. azadirachtin)
- EPA Reg. No. 89152-4, Ecoworks EC (Ecostadt Technologies LLC, a.i. neem oil)
ODA encourages growers in Malheur County producers applying chopped or shredded onion debris on fields to consult their crop advisor or Oregon State University Extension to determine the appropriate agronomic rate. For pesticide questions, please call ODA’s Pesticides program at 503-986-4635. To receive updates on ODA rulemaking and comment opportunities please subscribe.
