Aqueous extracts from different organs of 36 plant species were evaluated
for their antifungal activity against Fusarium oxysporum f. sp. niveum, Rhizoctonia
so/ani. and Botrytis cinerea. The extracts of eight plants. clove. garlic. jojoba.
ucuance, onion. pepper, rosselle and thyme highly suppressed the mycelial growth Of
the three tested fungi as well as the spore germination of B. cinerea. The reduction in
mycelial growth ranged from 88 to 100%. Results revealed that mycelial growth was
completely inhibited when tested fungi were exposed to garlic extract for 15 min or
clove extract for 2 hr. Emergence of watermelon seedlings in soil infested with F.
oxysp < /em>orum f . s p. n iveum was 1 00% when the soil was treated with clove or garlic
extract. The same results were obtained when tomato seedlings grew in soil infested
with R. so/ani. Scanning electron microscopy of R. so/ani mycelia treated with garlic.
liQuarice. rosselle and thyme extracts showed collapse of the hyphae and shriveling of
their cell walls.