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# California proposes lower annual limit for tree-hole fumigation
- URL: https://www.theamericanquorum.com/state-news-california-tree-hole-fumigation-proposed-limit-20261102/
- Published: 2026-11-02T15:16:15.000Z
- Updated: 2026-11-02T15:16:15.000Z
- Description: DPR proposes a 60-hole annual limit per acre while seeking permanent authorization for an existing interim fumigation method. The measure is not adopted.
- Author: News Desk
- Tags: Policy, California

*Illustration: AI-generated orchard scene; not a photograph of a specific property or pesticide application.*

California pesticide regulators are proposing to reduce the annual number of individual tree holes that may be fumigated on an acre while making an existing temporary authorization permanent. The action concerns 1,3-dichloropropene, known as 1,3-D, used to treat soil where replacement trees will be planted.

The Department of Pesticide Regulation’s [rulemaking docket](https://www.cdpr.ca.gov/proposed-regulation/dpr-26-006-13-dichloropropene-field-fumigation-method-tree-hole-method/?ref=theamericanquorum.com) lists the measure as proposed, not adopted. Its comment period runs through December 14, 2026\. The proposal therefore should not be read as a new permission already in force.

The [public notice](https://www.cdpr.ca.gov/wp-content/uploads/2026/10/dpr%5F26-006%5Foal%5Fnotice.pdf?ref=theamericanquorum.com) provides online, email and mailing routes for written comments. It warns that comments, attachments and associated contact information become part of the public record and may be released on request. Contact information is not required when using the online portal. Readers considering a submission should consult the notice directly; TAQ has not submitted a comment on the proposal.

The central numerical change is an annual ceiling of 60 treated tree holes in any acre. DPR’s [proposed text](https://www.cdpr.ca.gov/wp-content/uploads/2026/10/dpr%5F26-006%5Foal%5Ftext.pdf?ref=theamericanquorum.com) also specifies a maximum of 1.85 pounds of active ingredient per hole, or the product-label maximum if lower. Those proposed limits are distinct from a finding about actual exposure or health outcomes.

Current [interim conditions](https://www.cdpr.ca.gov/wp-content/uploads/2026/03/volume%5F3%5Fappendix%5Fj.pdf?ref=theamericanquorum.com) allow up to 166 holes per acre annually and cap each hole at two pounds or the label maximum, whichever is lower. That label qualification matters: the written ceiling is not necessarily the rate permitted for a particular product.

The interim method was authorized in September 2024 for three years. It provides an alternative to treating a larger orchard area when individual dead or diseased trees are replaced. Permanent authorization would require regulatory action before that temporary approval expires in September 2027.

In its [supporting analysis](https://www.cdpr.ca.gov/wp-content/uploads/2026/10/dpr%5F26-006%5Foal%5Fisor.pdf?ref=theamericanquorum.com), DPR says its use-data review found that more than 99% of tree-hole applications occurred in walnut orchards. The agency links its proposed lower ceiling to orchard spacing, use patterns and modeled emissions. Those are the department’s findings and rationale, not independent confirmation by TAQ that the proposed changes will produce particular environmental results.

Existing restrictions also remain important to understanding the comparison. Current interim conditions require a 100-foot setback from occupied structures for seven days and prohibit tree-hole fumigation during December. DPR’s [March update](https://www.cdpr.ca.gov/cac-letter/updates-to-pesticide-use-enforcement-program-standards-compendium-volume-3-restricted-materials-and-permitting-appendices-j-13-dichloropropene-and-n-volatile-organic-compounds/?ref=theamericanquorum.com) clarified that the December prohibition was consistent with the original decision. It is not a newly announced ban.

The proposal would retain method code 1230 in the permanent regulatory framework. The materials also distinguish occupied-site setbacks from separate buffer-zone provisions; the absence of one requirement should not be described as the absence of all separation protections.

This account is limited to what the agency’s proposal and existing records establish. It does not assess the adequacy of DPR’s emissions modeling or substitute for product labels, permits or county enforcement decisions.