Liverwort Control: An Ancillary Role for Ozone-based Irrigation Water Treatment Systems?

Abstract

<jats:p><jats:italic>Marchantia polymorpha</jats:italic> L. (a thalloid liverwort) is a common plant pest in nursery and greenhouse production systems. The rapid growth and dissemination of this pest can result in heavy mats of thallus tissue on the surface of pots, which restrict water penetration, compete for nutrients, and provide a habitat for other pests and disease vectors. The sensitivity of liverwort to aqueous ozone was examined to determine if routine use of ozone, as a component of an irrigation water remediation strategy, could provide ancillary services in the form of liverwort management. Three experiments were performed to evaluate contact time (CT) thresholds and application frequencies suitable for liverwort management applications. The first two experiments confirmed that CT is a suitable process control parameter with a base liverwort management threshold occurring between CT 0.84 and 1.68 mg·L<jats:sup>−1</jats:sup>·min under the conditions used. The third experiment examined the effect of application frequency at a CT of 3.75 mg·L<jats:sup>−1</jats:sup>·min, which was previously determined to be compatible with select woody perennial species. Three and five applications per week resulted in reduced liverwort growth and fecundity.</jats:p>

A Review of Common Liverwort Control Practices in Container Nurseries and Greenhouse Operations

“…Other organic products such as pelargonic acid, acetic acid products, d-limonene, and ammonium nonanoate have shown some suppression of common liverwort, but these compounds often require repeated application and can cause severe damage to ornamentals crops (Table 2). Graham and Dixon (2012) reported that the maintenance of a small residual aqueous ozone concentration during the distribution of irrigation water to the crop has the potential to offer some level of common liverwort control. They conducted experiments to evaluate contact time thresholds and application frequencies suitable for common liverwort management.…”