Failure of black cohosh (Actaea racemosa L.) rhizome transplants: potential causes and forest farming implications
Black cohosh (Actaea racemosa L.) rhizomes are harvested extensively from eastern North American forests and sold worldwide for treatment of menopausal symptoms. While forest farming is encouraged to reduce wild-harvest impacts, little information is available to aid landowners in successfully cultivating black cohosh. This study examined survival and multi-year growth of 200 black cohosh rhizomes collected from an Appalachian deciduous forest and transplanted to a similar forest type. By the second year after transplant, fewer than 40 % of rhizomes produced above-ground growth and mean rhizome biomass declined by more than 50 %. Shoot biomass was the greatest predictor of below-ground biomass; however, leaf area provided a reasonable, non-destructive means of estimating this commercially- important biomass. Our results suggest that pretransplant rhizome condition is particularly important to transplant success. Low biomass, lack of roots, and fungal infection all were associated with reduced plant survival. Based on this and associated studies, we recommend careful site selection for propagation, including circumneutral or lime-amended soils and light to moderate shading. Well-drained soil appears particularly important to discourage fungal infection. Understanding conditions for successful transplanting of black cohosh rhizomes can improve forest farming and contribute to sustainable management of this and other non-timber forest products.