Delayed-release clay-based delivery system for mustard-derived biopesticides

Overview

Mustard-derived biopesticides are effective against a broad range of plant pathogens but are difficult to deploy in the field. Their active compounds are released prematurely under high humidity and soil moisture, which reduces pest control performance and creates safety hazards for handlers. This technology addresses that challenge through a delayed-release delivery system built on natural clays.

The approach separates the two components required to generate the active biopesticide. Glucosinolate precursors and the myrosinase enzyme are extracted from mustard meal and independently deposited onto natural clay particles. Because the negatively charged glucosinolates and their hydrolysis products are not tightly bound to the clay surface, they are efficiently released when soil moisture rises above field capacity. This compartmentalized design allows the precursor and enzyme to remain stable during storage and application, then activate only when field conditions trigger hydrolysis.

Technical specifications

• Source materials: Brassica juncea and Sinapis alba mustard meals provide glucosinolates (including sinigrin and sinalbin) and myrosinase enzyme.
• Extraction processes: Crude extraction methods have been developed and validated for glucosinolates, thiocyanates, and other biologically active chemicals, as well as for myrosinase in dry formulation.
• Carrier system: Natural clays serve as the deposition substrate, taking advantage of negative charge repulsion to enable controlled desorption of active compounds.
• Sequential deposition: Glucosinolate precursors and myrosinase are incorporated onto two separate clay types to keep the reaction components apart until activation.
• Formulation method: A bench-top spray dryer is used to deposit the enzyme and precursor onto clay particles at varied drying temperatures and flow rates.
• Activation trigger: Addition of water exceeding soil field holding capacity initiates hydrolysis, releasing the active biopesticide at the intended time and location.
• Validated behavior: Laboratory experiments confirm controlled desorption of sinigrin and sinalbin from the natural clay carriers.

Technology readiness level

The technology is at an early-to-mid stage of development. Extraction protocols for glucosinolates, thiocyanates, and dry myrosinase formulations have been established, and proof-of-concept experiments have demonstrated controlled desorption of key precursors from natural clays. Ongoing work is focused on optimizing the spray-drying parameters and the sequential modification of two natural clays to create a fully compartmentalized delivery system. Further validation is needed to confirm field-scale performance, shelf stability, and efficacy against target plant pathogens under real agricultural conditions.