XVI International Botanical Congess

Garlic mustard is an exotic plant species in northeastern USA and adjacent Canada, where it displaces native forest understory plants. Garlic mustard is non-mycorrhizal, however, about 75% of understory plants are mycorrhizal. Water leachates of garlic mustard prevented germination of azygospores of the AM fungus Gigaspora rosea. Fifty g of air-dried plant tissue was soaked in 1000 ml of sterile distilled water for 24 h. The resulting leachate was passed through coarse sieves, then through a 0.2 mm millipore filter, and added to Bacto agar. Four surface sterilized spores were placed on the agar surface in a petri dish with a tomato seedling. In 10 control plates, 33 of 40 azygospores germinated. Seven of ten tomato seedlings in control plates were colonized by G. rosea. No spores germinated in the ten treatment plates.