However, systematic investigation of the antifungal
activities of essential oils and their constituents predate
those of the insecticidal properties. Kurita et al. (1981)
screened 40 such compounds against seven species of
fungi (primarily food spoilage organisms), and Singh
et al. (1980) similarly screened "ve essential oils against
22 species of fungi, including both human and plant
pathogenic types. More recently, Muller-Riebau et al.
(1995) screened nine essential oils against four species of
plant pathogenic fungi, whereas Wilson et al. (1997)
screened 49 essential oils against the fruit pathogen
Botrytis cinerea. In the former study, antifungal activity
was strongly associated with monoterpenic phenols, especially
thymol, carvacrol and eugenol, in the oils. Some
of the essential oils and constituents found to be insecticidal
(e.g. eugenol) were previously reported to be active
against a range of plant pathogenic nematodes
(Sangwan et al., 1990), and most recently some essential
oils were shown to e!ectively inhibit plant germination,
suggesting their potential use as bioherbicides (Dudai
et al., 1999).