Effect of garlic mustard [Alliaria petiolata (Beib. Cavara & Grande)] extracts on plants and arbuscular mycorrhizal (AM) fungi

We examined the effects of garlic mustard (Alliaria petiolata) leachates on germination of arbuscular mycorrhizal (AM) fungal spores, colonization of plant roots by AM fungi and germination and root growth of monocot and dico t plants under laboratory conditions. In the field we examined the effect o f garlic mustard on AM inoculum potential (MIP). Water leachates of garlic mustard prevented germination of spores of the AM fungus Gigaspora rosea, i nhibited the formation of AM associations with tomato (Lycopesicum esculent um) and significantly reduced germination of tomato, seeds. Garlic mustard leachates also reduced root length of tomato and sorghum (Sorghum bicolor) seedlings. Under field conditions we found a significant negative correlati on between the density of garlic mustard and the mycorrhizal inoculum poten tial of the soil in which the plants grew. These results suggest that garli c mustard may reduce the competitive abilities of native plants by interfer ing with the formation of mycorrhizal associations and root growth.