Antifungal activities of some medicinal plant extracts against Colletotrichum gloeosporioides (die-back) and Pestalotia theae (grey blight) of tea

Abstract

The research work was carried out to evaluate the antifungal activities of leaf extracts of four medicinal
plants viz. Azadirachta indica (Neem), Polygonam barbatum (Bishkatali), Adhatoda vasica (Basak) and Terminalia arjuna
(Arjun) against two tea fiingi Colletotrichum gloeosporioides (Die-back) and Pestalotia theae (Grey blight). Leaf extracts of
these plants were prepared by using distilled water, ethanol absolutes (95%) and ethanol (70%) as solvents. After that, three
concentrations (1%, 1.5%) and 2%) of leaf extracts of these four plants were prepared. The antifungal activities of crude extracts
were investigated by the poison food technique against these two experimental fiingi. The results showed that extracts of all the
four plants had direct effect on both fiingi. Among all the concentrations of leaf extracts of the four experimental plants diluted
in distilled water against Colletotrichum gloeosporioides, all concentrations of Adhatoda vasica (Basak) exhibited the highest
growth inhibition (100%) and Polygonam barbatum (Bishkatali) at 1% concentration showed the lowest growth inhibition
(38.88%). And against Pestalotia theae, Adhatoda vasica (Basak) at 2% concentration showed the highest effect (86.66%)
and Polygonam barbatum (Bishkatali) at 1% concentration exhibited the lowest effect (05.55%). As all the concentrations
of leaf extracts of respective plants diluted in ethanol absolutes (95%), all leaf extracts at all concentrations showed the same
growth inhibition (100%) against Colletotrichum gloeosporioides, and against Pestalotia theae, Azadirachta indica (Neem)
2%, Polygonam barbatum (Bishkatali) 2%, Adhatoda vasica (Basak) at all concentrations, and Terminalia arjuna (Aijun) 2%
showed the highest growth inhibition (100%)) and Polygonam barbatum (Bishkatali) 1% exhibited the lowest effect (97.11%)).
Among all the concentrations of leaf extracts of the said plants diluted in ethanol 70% against Colletotrichum gloeosporioides,
all concentrations oiAdhatoda vasica (Basak) showed the highest growth inhibition (100%) and Terminalia arjuna (Arjun) \%
exhibited the lowest effect (91.11%). And against Pestalotia theae, Adhatoda vasica (Basak) at 1.5% and 2% concentrations
showed the highest antifungal effect (100%) and Terminalia arjuna (Arjun) 1% showed the lowest effect (90%). In this study it
was investigated that among all concentrations of respective plants diluted in all solvents, Adhatoda vasica (Basak) exhibited the
highest effect on both fungi and Polygonam barbatum (Bishkatali) showed the lowest growth inhibition. Among the solvents,
ethanol extracts showed more grovrth inhibition of both fungi than other leaf extracts. From this research work this is evident
that all the plant extracts are potential antifungal agents against experimental both tea fungi, and the effectiveness of most of the
plant extracts increases proportionally with the increase in doses and decreases with time.