Wild Blueberry in a Context of Production Guide... Sustainable Development 43. Sweet-Fern Latin name: Comptonia peregrina (L.) Coulter French name: La comptonie voyageuse Sweet-fern is the only species of Comptonia found in North America. It occurs in sandy terrain, often in association with jack pine. It grows in large dense formations and offers signifi cant competition to blueberry cultivation in places where it is established. Herbicides are of variable effectiveness against it, which explains why this weed is of such concern to wild blueberry growers. DESCRIPTION Sweet-fern is not a fern but a deciduous shrub, 0.5 to 1.0 m in height, extensively branched and aromatic (Figure 1). Its fern- like leaves are alternate, close, long and narrow with many lobes, distinctively fragrant when crushed. Ecologically it is well- adapted to the dry soils of northern regions, where it thrives. For example, its bur-like fruit produces resinous secretions that protect it from desiccation. Like legumes, it fi xes nitrogen from the air. The species propagates especially well on open ground that has been cleared by fi re, for its rhizomes run horizontally under the ground, producing roots and sending up aerial stems. As with blueberries, mowing or burning a fi eld will stimulate sweet-fern to multiply further. CONTROL Hand-pulling of sweet-fern is possible, but must be done before the seeds are dispersed. Gloves should be worn to avoid injury to the hands. When sweet-fern is taller than the blueberries, mowing the upper level can slow its development provided this is done before the seeds are released. Ideally, if there is suffi cient regrowth for such mowing to be done repeatedly over the summer, the plant’s nutrient reserves will gradually be exhausted. This is most effective when the fi eld is in a growth year. There is no data showing the long-term effectiveness of either hand-pulling or mowing for controlling sweet-fern in blueberry fi elds. Herbicides Glyphosate and hexazinone, applied in the growth year, are registered herbicides against sweet-fern in blueberry produc- tion. Their effectiveness varies however. The herbicides available for controlling this weed are presented in Leafl et 19 in this series, Pesticides Used in Wild Blueberry Production. Figure 1. Infestation of sweet-fern Source: Suzanne Hardy, Enracinart

1 43. Sweet-Fern

COMPLEMENTARY LEAFLETS 15. Integrated Pest Management in Wild Blueberry Production 19. Pesticides Used in Wild Blueberry Production REFERENCES Desjardins, È.-C. and R. Néron. 2010. Guide d’identifi cation des alliés et ennemis du bleuet nain : Insectes, maladies et végétaux. Centre de recherche Les Buissons. p. 152. Marie-Victorin, Frère. 1995. Flore laurentienne. Troisième édition. Les Presses de l’Université de Montréal. p. 157. Ministère des Terres et Forêts. 1974. Petite fl ore forestière du Québec. Éditions France-Amérique. p. 128. Sampson, K.V. and D.L. McCully. 1990. Weeds of Eastern Canadian Blueberry Fields. Nova Scotia Agricultural College Bookstore. Truro, Nova Scotia. p. 186. Yarborough, D. 2001. Cultural Management for Weeds in Wild Blueberries. Fact Sheet No. 252. The University of Maine. Cooperative Extension. [Online]. http://umaine.edu/blueberries/factsheets/management/cultural-management-for-weeds-in-wild-blueberries/ (Page consulted on September 15, 2010).

PROJECT COORDINATION PUBLISHING Sophie Gagnon, Agronomist, Project Management Chantale Ferland, M.Sc., Publishing Project Offi cer, CRAAQ, Coordinator, Agrinova, Alma Québec Lyne Lauzon, Publications Coordinator, CRAAQ, Québec ADAPTATION Sophie Gagnon, Agronomist, Project Management TRANSLATION Coordinator, Agrinova, Alma Rod Willmot, M.A. REVISION LAYOUT AND GRAPHIC DESIGN Danielle Bernier, Agronomist-Weed Scientist, Ministère de Sylvie Robitaille, Computer Graphics Technician, CRAAQ, l’Agriculture, des Pêcheries et de l’Alimentation du Québec, Québec Québec Gaétan Chiasson, Agronomist, Development Offi cer, New Brunswick Department of Agriculture, Aquaculture and Fisheries, Bathurst Laurier Tremblay, Agronomist, Ministère de l’Agriculture, des Pêcheries et de l’Alimentation du Québec, Bergeronnes

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Wild Blueberry Production Guide 2