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Abstract
Liverwort and moss are economically significant weeds across a range of US container production sites, including forest seedling greenhouse culture in the Pacific Northwest. We have demonstrated the effectiveness of essential oils, or distilled plant extracts, in controlling liverwort and moss container weeds over three seasons of trials. When applied at the appropriate concentration and volumes, essential oils act as an effective contact herbicide. There is little or no residual, and under heavy pressure, liverwort and moss can re-establish within 2 weeks of knockdown. The applicator must pay close attention to method and application rates to successfully control weeds while avoiding crop damage, such as leaf or needle burn. Leaf wilt following the first drying cycle has occasionally been observed, with root damage suspected but not confirmed. This paper summarizes integrated pest management practices to limit the invasion and spread of liverwort and moss in containers, details postemergent trial results of directed-spray and over-the-crop herbicide applications, suggests guidelines for species and stocktype stages, and provides a checklist of procedures when applying essential oils.
Parent Publication
Citation
Khadduri, Nabil. 2011. Using essential oils to control moss and liverwort in containers. In: Riley, L. E.; Haase, D. L.; Pinto, J. R., tech. coords. National Proceedings: Forest and Conservation Nursery Associations - 2010. Proc. RMRS-P-65. Fort Collins, CO: USDA Forest Service, Rocky Mountain Research Station. p. 133-138.
