Inhibition of cucumber green mottle mosaic virus by extract of some ferns.
Thirteen species of ferns were tested for their inhibitory effects against cucumber green mottle mosaic virus (CGMMV) on Cucurbita pepo cv. Caserta. The extracts of Adiantum caudatum, Dryoteris filix-mas, Polypodium parasiticum, P. obligatum and P. nitro-corpum showed the highest inhibitory effect. More than 90% infectivity of the virus was inhibited in vitro. The extracts of Pteridium aquilinum, Vittaria elongata, Ampelopteris [Cyclosorus] and Nephrolepis tuberosa exhibited 70% inhibition. The extracts of Adiantum capillus-veneris and Pteris critica showed above 60% inhibition. Less than 50% inhibition of infectivity was recorded by the extracts of Marsilea minuta and Azolla pinnata. In the second experiments, different dilutions of the extracts of A. caudatum, D. filix-mas and P. paraciticum showing more than 93% inhibition were tested. The results indicate that inhibitory activity of the extracts was low. The dilution by 90% of the extracts of A. caudatum, D. filix-mas and P. paraciticum resulted in 75, 70 and 65% inhibition of the virus, respectively. In the third series of experiments, the extracts of A. caudatum, D. filix-mas and P. paraciticum were sprayed on leaves of young host plant before inoculation. The 3 extracts greatly inhibited the multiplication of CGMMV.