Martin, Vivian – Invasive rose control in the McMaster Forest (Susan Dudley)

Rosa multiflora (multiflora rose) and Rosa rubiginosa (sweetbriar rose) are two woody non-native invasive shrubs found in the McMaster Forest (MF), among other areas in North America, with vigorous root systems and a tolerance for a wide variety of conditions. Based on data from a dozen bushes of each species (15 to 20 rosehips per bush) collected winter 2017, it was found that in local populations, the average multiflora rosehip contains an average of 6.31 seeds, while the average sweetbriar rosehip contains an average of 16.79 seeds, with no evident correlation to plant size. This study sought to create and test a viable control strategy for both species. Analyzing available research from the past six decades on multiflora rose control while considering the scale of the local problem, it was determined that girdling bushes, that is to remove strips of bark, and apply a herbicide (glyphosate), was the most viable solution. Forty rose bushes, twenty of each species, were included in the study. Half of the bushes of each species were girdled and treated with a 1.5% concentration solution of glyphosate during the winter season. Due to the passing of less than one growing season, results are not yet available indicating the efficacy. However, it has been determined that, from a practical standpoint, this technique is highly executable and could be considered for other invasive species crowding out and using the resources of native species in the MF.