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Broadleaf herbicide screening trial for ginseng

Project Code: SCR06-001

Project Lead

Rob Grohs - University of Guelph


To evaluate reduced-risk herbicides for potential to control broadleaf weeds in ginseng and to provide recommendations for reduced-risk candidate herbicides to be pursued for registration in Canada.

Summary of Results

American ginseng (Panax quinquefolius) is a member of the Araliaceae family. This perennial is native to the deciduous forests of eastern Canada and the eastern United States. Ginseng is grown for its roots, which are used in traditional Chinese medicine and increasingly in conventional medicine. Ginseng is grown in two Canadian provinces, Ontario (68% of production) and British Columbia (32% of production).

Glyphosate is the only registered herbicide that can be used in ginseng to control broadleaf weeds. However, it is of limited value to growers because of the narrow application window in the spring and the high risk of crop injury associated with field use.

New chemicals are therefore needed to control broadleaf weeds in ginseng production. A study to evaluate the efficacy of seven reduced-risk herbicides was conducted in 2006 and in the spring of 2007 at the Simcoe Research Station of the University of Guelph, in Ontario.

Two trials were conducted, one with one-year-old ginseng plants (seedlings) and another with two-year-old ginseng plants (established plants). The experimental design was a randomized complete block design with four replications. Plots were 1 m by 7 m.

The seven herbicides evaluated were applied at three rates: 0.5X, 1X and 2X. Herbicide efficacy was evaluated by collecting data on injury caused to the ginseng plants (summer 2006) and on root yield (spring of 2007).

Only one of the seven reduced-risk herbicides tested did not cause serious injury to the ginseng plants, namely Outlook (dimethenamid-P). Dimethenamid-P was effective against several broadleaf weeds. This herbicide, applied at rates of 0.5X, 1X or 2X, caused no crop injury and did not result in any major reduction in root yield the following season. Outlook must be applied prior to weed emergence, directly in the weed germination zone.

In summary, of the seven reduced-risk herbicides tested, dimethenamid-P is the only candidate for registration for use in ginseng cultivation.

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