The objective of this work to study the effect of six plant
extracts, Ocimum basilicum (Sweat Basil), Azadirachta indica (Neem),
Eucalyptus chamadulonsis (Eucalyptus), Datura stramonium (Jimsonweed),
Nerium oleander (Oleander) and Allium sativum (Garlic) against
Alternaria solani in vitro and in vivo. In in vitro study
the leaf extracts of D. stramonium, A. indica and A. sativum at
5% concentration caused highest reduction of mycelial growth of A. solani
(44.4, 43.3 and 42.2%, respectively), while O. basilicum at 1 and 5%
and N. oleander at 5% caused the lowest inhibition of mycelia growth
of the pathogen. In greenhouse experiments the highest reduction of disease
severity was achieved by fungicide (Ridomil Plus 50% WP, 15% metalaxy+35% Copper
oxychloride, at 2 g L-1) 82.8% followed by the extracts of A.
sativum at 5% and D. stramonium at 1 and 5% concentration. The greatest
reduction of disease severity was achieved by Ridomil Plus 74.2% followed by
A. sativum at 5% and the smallest reduction was obtained when tomato
plant was treated with O. basilicum at 1 and 5% (46.1 and 45.2%, respectively).
Fungicide, D. stramonium and A. sativum at 5% increased the fruit
yield 85.7, 76.2 and 66.7% compared to infected control. All treatments, plant
extracts and fungicide (Ridomil Plus), significantly reduced the early blight
disease as well as increased the yield of tomato compared to infected control
under field condition.