ALOE VERA GEL ACTIVITY AGAINST PLANT-PATHOGENIC FUNGI

The antifungal activity of Aloe vera gel at 1-10(5) mu l l(-1) was tes ted on four common postharvest fruit pathogens: Penicillium digitatum, P. expansum, Botrytis cinerea, and Alternaria alternata. The natural gel suppressed both germination and mycelial growth with P. digitatum and A. alternata being the most sensitive species. Spore survival of P . digitatum, A. alternata, and B. cinerea was reduced by 15-20% at 1 m u l l(-1), but the gel was similarly effective against P. expansum onl y when the concentration exceeded 10(3) mu l l(-1). For the first two species, the suppressive effect of the gel increased with an increase in the concentration, culminating in 95% reduction in spore survival a t 10(5) mu l l(-1). B. cinerea, however, responded with a partial germ ination recovery when the gel concentration was greater than 10 mu l l (-1) The inhibitory effect of the plant gel on colony growth was exhib ited at 1 mu l l(-1), when a 67-69% reduction in radial growth was rec orded for P. digitatum, A. alternata, and B. cinerea, and a 19% reduct ion for P. expansum after five days on potato dextrose agar (PDA) at 2 3 degrees C. The effect of the gel on disease development in P. digita tum-inoculated grapefruit was expressed by both a delay in lesion deve lopment and a significant reduction in the incidence of infection foll owing dipping in a concentration of plant gel of 10(3) mu l l(-1).