Roots of American ginseng are common ingredients in herbal medicines. However, being a root crop subjects ginseng to attacks by soil-dwelling organisms, which cause root rot of ginseng seedlings. In order to prevent damage to the roots, growers typically fumigate fields before the ginseng crop is planted.

“An important component of many traditional Asian herbal medicines is dried root of American ginseng (Panax quinquefolius L.). … Although indigenous to the forests of eastern North America, most of the world supply of dried root is now provided by crops grown in cultivated fields under artificial shade structures. Over two-thirds of Canada’s ginseng crop is grown in the sandy soils of southwestern Ontario.”

“Current production methods provide environments favourable to disease development, and crop loss due to disease is significant. Although ginseng germplasm is diverse, disease-resistant cultivars are not available. … To reduce risk of damage from soilborne species of Pythium and nematodes, ginseng growers normally fumigate fields prior to seeding.” 

Authors: R.D. Reeleder¹, J. Miller¹, B. Capell¹ and J. Schooley²
Affiliation: ¹Agriculture and Agri-Food Canada, Ontario, Canada; ²Ontario Ministry of Agriculture, Ontario, Canada.
Title: Mefenoxan sensitivity and the impact of fumigation on Pythium species and Phytophthora cactorum in ginseng soils.
Publication: Canadian Journal of Plant Pathology. (2007) 29:427-436.