California Tightens 1,3-D Soil Fumigation Rules for 2026 — What Growers and Importers Need to Know

California's Department of Pesticide Regulation (DPR) has replaced the former township-cap system for 1,3-Dichloropropene (1,3-D) with a new emission-based framework, effective January 1, 2026. The revised rules are designed to keep 1,3-D air concentrations below DPR's health-based thresholds while giving growers clearer, method-specific guidance.

Under the new requirements, the baseline setback from occupied structures is 100 feet, with longer distances required for certain application methods, rates, or block sizes — and Coastal counties (15 of them) face more stringent setbacks than the 40 Inland counties due to differing weather conditions. The maximum application rate is capped at 332 pounds of 1,3-D active ingredient per broadcast-equivalent acre, and the maximum treated block size is limited to 80 acres, with smaller limits under specific conditions. Fields must also meet a minimum soil moisture threshold — 50% of field capacity at a depth of three to nine inches — before fumigation can proceed, and overlapping applications within 36 hours of a completed treatment trigger combined setback calculations.

Early results are visible in DPR's own tracking: statewide 1,3-D usage in Q2 2026 remains below levels typical before the 2024 regulatory overhaul, though a small number of townships in Merced and Kern counties exceeded historical caps amid expanded local crop cultivation. DPR says it will continue monitoring compliance and effectiveness through its annual report.

For international buyers and growers relying on 1,3-D as a pre-plant soil fumigant, the takeaway is straightforward: regulatory compliance is becoming more technical and site-specific, and supply chain reliability now depends on sourcing from partners who understand both the chemistry and the evolving regulatory landscape. Sinocropchem supplies 1,3-D and related soil fumigants to international markets with full documentation and technical support — contact our team to discuss specifications, compliance documentation, or upcoming order planning.