found that while the crude extracts strongly stimulated Bacillus subtilis growth,
separation of various fractions by thin layer chromatography revealed a fraction
that inhibited bacterial growth. The inhibitor in the Aloe veru gel affecting fungal
development has not been isolated; however, the inhibitory effect of the gel at
very low concentrations (1 ~11~‘) weakens the possibility that this effect is caused
by the high-osmotic potential of the gel (Heggers et al., 1979). Since Fujita et al.
(1978) found that the antifungal activity ofAloe arborescens had been eliminated by
gel heating, a similar heat-labile component may be responsible for the antifungal
activity ofAloe Vera gel.
Stimulatory effects of Aloe gel on spore survival was shown in this study for
Botytis only, as was expressed by the reduced incidence of spore inactivation with
the increase in gel concentration.
As well as the antifungal properties exhibited by Aloe Vera extracts in vitro, their
suppressive effects have also been demonstrated clearly in vivo for E! digitatum in
inoculated citrus fruit. The reduction in the incidence of decayed fruit is in good
agreement with the in vitro experiments where gel applications reduced the number
of viable spores.
Thus, Aloe veru gel may offer a natural means of controlling fungal disease
in certain host-pathogen systems. Application of Aloe Vera gel, used also as an
internal medicinal remedy (Klein and Penneys, 1988), to control postharvest fungal pathogen decay of agricultural produce might be an attractive alternative to
chemical fungicides.