Organic mulch allelopathic extracts for liverwort biocontrol in ornamental production

Overview

Liverwort (Marchantia polymorpha) is a major weed problem in greenhouse and nursery container ornamental production. Current control options are limited: chemical herbicides can cause phytotoxicity to crops, and hand-weeding is labor-intensive and costly. This research investigates whether allelochemicals (naturally occurring bioactive compounds) released from organic mulches can serve as biopesticides, inhibiting liverwort gemmae germination or reducing its growth. The goal is to develop an effective, sustainable weed management solution that improves ornamental crop quality and market value.

Technical specifications

Research approach:

• Extracts will be obtained from four organic mulches: rice hull, hardwood, cocoa hull, and pine bark
• Extraction will use a modified EPA 1312 synthetic precipitation leaching procedure to isolate water-soluble allelochemicals
• Greenhouse trials will test mulch extracts applied to soil-filled nursery pots
• A mature liverwort source pot will be placed near treated pots to provide inoculum
• Liverwort thalli coverage will be measured bi-weekly as a percentage of substrate surface

Key preliminary findings:

• Rice hull and hardwood mulch achieved 95-100% liverwort control in prior lab trials
• Rice hull and hardwood mulch improved Hosta sp. growth in container production
• The mechanism of control may involve both physical mulch properties and allelopathic chemical effects, which this research aims to isolate and characterize

Technology readiness level

This research is at an early-to-mid stage of validation. Preliminary proof-of-concept data already demonstrates strong liverwort suppression (95-100%) and improved hosta growth using rice hull and hardwood mulches. The current phase focuses on isolating the allelopathic component from physical mulch effects through controlled extract testing. Further field validation across multiple ornamental crop systems and mulch types will be needed before commercial recommendations can be developed for grower adoption.