CDPR Proposes Changes to Regulations on Tree-Hole Method for 1,3-D

The Department of Pesticide Regulation (DPR) has announced plans to amend fumigation requirements for 1,3-Dichloropropene Field Fumigations. In summary, the proposed action allows for the use of 1,3-dichloropropene (1,3-D) to fumigate individual tree-holes (also known as tree planting sites), making permanent the three-year interim approval of the method granted in September 2024. The proposed action also establishes additional restrictions on use of the tree-hole method, including more stringent limits on the number of tree-holes per acre. The broad objective of the proposed regulation is to allow for use of the tree-hole method, including for use in tree replant scenarios. In consideration of historical usage information, cost relative to broadcast applications, and orchard planting density, the following use restrictions are proposed:

• A maximum per hole application rate of 1.85 pounds of active ingredient (AI).

• The minimum distances between any two tree-hole planting sites must be 15 feet center to center. If trees are planted less than the 15-foot minimum, tree-hole applications must be separated by at least 24 hours.

• A maximum number of 60 tree-holes per acre in a calendar year.

• The minimum injection depth for fumigant is 36 inches.

• Tilling, soil, and application requirements.