The extracts of A. indica inhibited the growth of the
pathogen in culture (Table 1). The oil and alcohol extracts,
signi"cantly reduced the radial growth of P. oryzae
as much 83.6 and 76.8%, respectively, in comparison
with the alcohol control. These were followed by cold
water extracts and then hot water extract as compared
with the water control. There was no growth inhibition in
the control treatment containing water, however, a slight
reduction in growth (5.8%) was recorded in the control
medium cataining alcohol. The reduction in growth of
the pathogen in vitro by oil extract was not signi"cantly
di!erent from alcohol extract. There was a signi"cant
di!erence between the cold and hot water treatments.
The oil and alcohol extract sprays reduced blast incidence
signi"cantly, ranging from 10.2 to 19.5% and 21.5
to 23.5%, respectively, whereas the control experiments
recorded 100% and 88.6}92.7% for water and alcohol,
respectively, at 2 d before or after inoculation of rice with
the pathogen. Carbendazim at 0.1% a.i. spray was not as
e!ective as the oil extract in reducing the incidence of the
disease over all tested periods. However, the checking of
the spread of the disease in vivo by carbendazim was not
signi"cantly di!erent from that of oil and alcohol extracts
(Table 2). The highest disease incidence score was
registered with hot water extract sprays after 20 d and
this was signi"cantly di!erent from the cold water treatment.
Delay in treatment of P. oryzae inoculated rice
plants with neem extracts until after disease symptoms
were evident decreased the e$ciency of the extracts as
compared with plants treated with the extracts 2 d before
and after inoculation.
Results in Table 3 show that the pathogen completely
infected rice plants not treated with the neem extracts or
carbendazim. As compared with the untreated controls,
the severity of blast disease was reduced in rice plants
treated with oil, alcohol or cold water extracts even after