Valorizing Tree-Nutshell Particles as Delivery Vehicles for a Natural Herbicide.

Area of Science:

• Agricultural Science
• Environmental Science
• Sustainable Chemistry

Background:

• Tree nut by-products, like nutshells, are abundant agricultural waste with limited market applications.
• Salicylaldehyde (SA), a natural volatile compound, possesses herbicidal and antifungal properties.
• Developing nutshells as controlled-release herbicide systems offers sustainable weed management and waste valorization.

Purpose of the Study:

• To develop nutshell by-products as effective herbicide delivery systems for sustainable weed control.
• To evaluate the pre- and post-emergent herbicidal efficacy of salicylaldehyde (SA) delivered via walnut shells.
• To investigate the influence of solvents and soil covering on SA's herbicidal activity.

Main Methods:

• Walnut shell particles were saturated with 0.8 to 1.6 M salicylaldehyde (SA).
• SA solutions in dimethyl sulfoxide (DMSO) and 60% ethanol were tested.
• Herbicidal efficacy was assessed on monocot (turfgrass) and dicot (Chinese cabbage) plants under covered and uncovered soil conditions.

Main Results:

• Pre-emergent: Dicot plants showed higher susceptibility to SA in DMSO than monocots, with germination reduced to 1-15%.
• Post-emergent: Complete weed control and plant death occurred within 5-7 days with SA fumigation.
• Ethanol-based SA (60%) demonstrated enhanced herbicidal activity, disrupting growth within 3 days, even without soil covering.

Conclusions:

• Tree nutshells serve as efficient, controlled-release delivery vehicles for salicylaldehyde (SA).
• SA exhibits significant pre- and post-emergent herbicidal activity against monocot and dicot weeds.
• Utilizing nutshells as SA delivery systems offers a sustainable method to valorize by-products, reduce waste, and mitigate carbon emissions.