Global Advanced Research Journal of Microbiology::::::GARJM>Al-Hazmi: Study on Effect of Neem (Azadirachta indica) leaves and seeds extract on the growth of six of the plant disease causing fungi.

This study was conducted in the Department of Arid Land Agriculture of the Faculty of Meteorology, Environment and Arid land Agriculture, King Abdul Aziz University, to study the growth of plant pathogenic fungi under the influence of the aqueous and ethanolic extracts of the leaves and seeds of Azadirachta indica . The aqueous and ethanolic extracts were used in the concentrations, 1:1, 1:10, 1:100, 1:1000 (v:v ). Six of the pathogenic fungi were used , Pythium aphanidermatum, Alternaria alternata, Bipolaris sorokiniana, Fusarium oxysporium, Helminthosporium sp. and Thilaeviobsis sp. The results showed that the growth of the fungi P. aphanidermatum, A. alternaria and H. sp. was mostly inhibited by the ethanolic extract of the Neem seeds compared to the other extracts, while no inhibitory effect was noticed for the tree seed water extract on the growth of P. aphanidermatum , Alternaria alternaria and H. sp. The least affected fungus by these seeds and leaves extract was Thialeviopsis sp. The seeds and leaves extracts were mostly affective in growth retardation of the fungi when applied at the highest concentration (1:1, v:v ), P. aphanedermatum was retarded by 21.74%, A. alternaria by 33.2%, B. sorokinianae by 40.27%, F. oxysporum by 57.26%, H. sp. by 38.56%, T. sp. by 23.40%. And the ethanolic seed extract is considered most effective e growth retarding of pathological fungi than the seed water and leaf ethanolic extracts . It can be said that the water and ethanolic seeds and leaves extracts of A. indica inhibited the growth of the studied fungi at different percentages.

Keywords: Neem- plant disease- pathological fungi.