Competitive and allelopathic effects of garlic mustard (Alliaria petiolata) on American ginseng (Panax quinquefolius)

Abstract

The purpose of this study was to test competitive and allelopathic effects of invasive garlic mustard on American ginseng (Panax quinquefolius) seedlings under natural conditions. For comparative purposes, we also examined the potential effects of the native striped violet (Viola striata). In order to partition effects of resource competition and chemical suppression via allelopathy, field soils were amended with activated carbon or left unamended. Activated carbon positively affected ginseng growth as well as biomass of competitors. Ginseng mortality tended to increase with garlic mustard presence, though activated carbon alleviated this response. Garlic mustard had no significant effect on ginseng seedling growth, while striped violet suppressed shoot length in the absence of activated carbon. Our results showed a surprising effect of activated carbon on plant growth, a potential allelopathic effect of the native striped violet and suggest that newly invaded ginseng populations with low densities of garlic mustard may be able to withstand its effects. However, recruitment within invaded populations may decline.

Interference of allelopathic wheat with different weeds

“…A plant species may interfere with other plant species through competition, allelopathy or both. Competition and/or allelopathy in crop–weed interactions occur frequently in cropping systems . Although the relative impacts of allelopathy in crop–weed interactions are still being elucidated, this non‐competitive interference influences the growth and establishment of weeds that may act either independently or synergistically with competition and other interactions.…”

“…An increasing number of studies have shown that the participation of allelopathy, which results from the allelochemicals released from crop varieties themselves, is also a key non‐competitive interference . There is a wealth of information on competitive and allelopathic interference between crop plants and weeds . However, when it comes to the relative impact of allelopathy either independently or synergistically with competitive factors on the growth and establishment of weeds, there is a lack of data, which calls for further studies.…”

“…Allelopathy in a crop involves the specificity of weeds based on the differing sensitivities of various species to the allelochemicals released from the allelopathic crop . Furthermore, the weed suppression effect is a joint action of allelopathy and competitive factors . Using a crop–weed mixed‐culture design has provoked a great deal of controversy owing to the neglect of competition and other interspecific interactions.…”

Do white-tailed deer and the exotic plant garlic mustard interact to affect the growth and persistence of native forest plants?

“…Garlic mustard reduces native plant germination, growth, and diversity by releasing secondary compounds (allelopathy) that diminish and disrupt mycorrhizal associations, altering soil chemistry, and outcompeting natives for space and resources Meekins and McCarthy, 1999;Stinson et al 2006;Roberts and Anderson, 2001;Prati and Bossdorf, 2004;Murphy 2005;Barto et al, 2010;Cipollini and Gruner, 2007;Stinson et al, 2006;Wolfe et al, 2008;Wixted and McGraw, 2010;Lankau, 2011). Deer could accentuate these impacts to native plants via ''apparent competition'' if deer and other herbivores avoid Alliaria to feed preferentially on native species.…”

Ecology and conservation of ginseng (Panax quinquefolius) in a changing world

“…The mere presence of invasives, however, does not demonstrate competitive effect. A follow‐up experimental study compared the effects of planted A. petiolata with that of a planted native species, Viola striata , around target ginseng plants . Alliaria increased seedling mortality, and treatment of soil with activated carbon reduced this effect somewhat, suggesting it may have been due to allelopathy.…”