Project Code: BPR16-041
Project Leads
Nancy Cain - Cain Vegetation Incorporated, Ontario
Objective
To demonstrate the use of MossKade as part of an integrated liverwort management system in ornamental crops
Background
Common liverwort (Marchantia polymorpha) has become a serious weed in Canada’s ornamental greenhouse and container production. This weed grows quickly, forming thick mats on the surface of pots. These mats block water from reaching the soil and can compete with ornamental plants for nutrients. Additionally, liverworts can create slip hazards for workers due to their slippery surfaces.
MossKade, a mixture of lactic acid and food ingredients such as protein, starch, and vegetable oil, is a post-emergence non-conventional herbicide. It works by suffocating liverworts, mosses, and algae through creating a topical layer that acts as a physical barrier. Canadian growers had identified MossKade as a key solution for liverwort management in ornamental crops. This project tested the effectiveness of integrated liverwort management strategies using MossKade. The strategy combined this product with other methods, including cultural practices, physical removal, and conventional herbicides, to control liverwort in container-grown oaks and in the alleys of pot-in-pot hydrangea beds at an Ontario nursery.
Approach
Three trials were conducted to evaluate integrated liverwort management: 1) first-year container stock of oaks (Quercus spp.); 2) second-year container stock of oaks; and 3) field alley sides of pot-in-pot hydrangeas (Hydrangea paniculata). Each trial had a different level of liverwort infestation, ranging from no liverwort in the first-year oaks to heavily infestation in the alley sides of pot-in-pot hydrangeas. The following tools were assessed individually or combined: MossKade, a pre-emergent herbicide application of flumioxazin (Broadstar® or SureGuard®), and a surface cover barrier (coarse hardwood sawdust, coconut fibre discs, and pine bark mulch). Treatments were assessed on liverwort injury and coverage throughout the experiment.
In the first-year container stock of oaks, liverwort typically appears in late August with more regular infestation by September. Since these pots did not have established liverwort populations, the focus was on preventing establishment. Five management treatments were tested, including: multiple applications of Broadstar®; the addition of MossKade with Broadstar®; a single application of MossKade in the fall; coarse hardwood sawdust applied in the summer before liverwort emerges; and coarse hardwood sawdust with a fall MossKade application.
Infestation in the second-year container stock of oaks was considered light to medium, with treatments focusing on eliminating the liverwort and preventing re-establishment. Four treatments were compared to an untreated control: three applications of MossKade with one fall application of Broadstar®; one fall application of MossKade; coconut fibre discs as a surface cover on emerged liverwort; and three applications of MossKade with coconut fibre discs.
The alley-side in the pot-in-pot hydrangea field bed was heavily infested. Treatments aimed to reduce the existing liverwort population and prevent re-establishment. Six treatments were compared to an untreated control: five applications of MossKade; two applications of MossKade with pine bark mulch applied afterwards; five applications of MossKade with fall application of SureGuard®; pine bark mulch alone on emerged liverwort; a single SureGuard® application in the fall; and a single MossKade application in the fall.
Results
MossKade was found to cause minimal injury to ornamentals in these experiments, with less than 1% contact injury noted on basal shoots of some oaks. This suggests that MossKade could be a viable control option for ornamentals sensitive to flumioxazin.
In the first-year container stock of oaks, using MossKade in combination with Broadstar® increased liverwort injury, resulting in efficient control compared to either product alone. Similarly, using MossKade with coarse sawdust improved control compared to sawdust alone. In the second-year stock of oaks, coconut discs alone and with multiple MossKade applications were the most effective in reducing liverwort coverage. Multiple applications of MossKade, along with a fall Broadstar® application, were not as effective at reducing liverwort coverage.
In the field alley side of the pot-in-pot hydrangea production, pine bark mulch effectively controlled liverwort a couple of weeks after application. Five applications of MossKade over the season, as well as two applications of MossKade before installing pine bark mulch, were also effective in injuring liverwort and reducing overall coverage.
This project demonstrated that MossKade can help control liverwort populations in ornamental production systems when used as part of an integrated management plan. MossKade complements other management tools focused on preventing liverwort emergence, providing additional control for escapees or to reduce populations before applying mulch or surface covers. However, MossKade is not registered in Canada, due to the registrant’s inability to fulfill data requirements for the regulatory review of the product profile.