Effect of Compost Tea and Plant Extracts on Sheath Blight and Blast Diseases of Rice (Oryza Sativa)
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Date
2013
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Journal ISSN
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Publisher
Uva Wellassa University of Sri Lanka
Abstract
Blast caused by Magnaporthe oryzae and sheath blight caused by Rhizoctonia solani are
destructive rice (Oryza sativa) diseases which reduce both grain yield and quality worldwide
(Ou, 1985). The widespread adoption of synthetic fungicides to control diseases has shadowed
by the health risks associated with applying or consuming the materials (Cookl and Baker,
1983). Compost tea is a type of biological control that has potential to suppress a broad range of
plant pathogens (Scheuerell and Mahaffee, 2002) and several higher plants have proved their
usefulness against a number of fungi (Dixitet et al., 1983; Singh et al., 1983).Therefore this
study was carried out to evaluate the fungicidal effect of Compost tea and some plant extracts
on Sheath Blight and Blast diseases of rice.
Methodology
M. oryzae infected rice leaves and R. solani infected rice sheaths were collected from the fields
to isolate the disease causing pathogens at the Pathology Laboratory, Rice Research and
Development Institute (RRDI), Batalagoda. Isolated fungal colonies on the PDA media were
used to examine microscopic characteristics for identification of organism and koch’s postulate
was confirmed. Hundred grams of Croton laccifer, Gliricidia sepium, Ardathoda vasica leaves
and Azaadirachta indica seeds were surface sterilized and grinded using pestle and mortar. The
extracts were diluted by adding 1 L of distilled water to each beaker. After 12hrs extracts were
strain through Whatman paper No. 1 filter papers and used as treatments. Bucked bubbler
method was used to prepare compost tea (Sustainable Agriculture Technologies. Inc.2008).
). Pure culture
of the fungus was placed at the center of each Petri dish with PDA media. Two filter paper discs
were impregnated with each treatment (plant extracts, compost tea, fungicide and distilled
water) were placed on the opposite sides to each other. Inhibition zones were examined using a
grid at intervals of 24hrs till the plates were filled with mycelia in either treatment. A pot
experiment was carried out between June-September, 2013 at RRDI; Batalagoda.
The treatments were arranged in Complete Randomized Design with three replicates. Seeds of
rice variety Bg 352 were used. Compost tea and plant extracts were applied every 2 week
interval after transplanting. R. solani inoculums were placed at the base of the tillers 10 weeks
after transplanting. Chemical fungicide was applied according to the label recommendations
once the symptoms appear. Relative lesion height, scale of disease severity (IRRI 1996) and the
per cent disease index (McKinney 1923) was calculated in every week after inoculation. Data
analyses were conducted using MINITAB 16 statistical software.
Results and Discussion
Microscopic observations show that the dimensions of mycelia are agreed with original
description of M. oryzae and R. solani (Supriya and Sharma, 2010, Ou, 1985).
As shown in figure 1 after 120 hours the Petri plates which contained control were fully covered
by mycelia of M. oryzae. All the other treatments recorded zone of inhibitions significantly
higher than the control. Highest zone of inhibition was obtained from fungicide and second
highest was recorded from compost tea followed by A. indica seed extract.
Description
Keywords
Agriculture, Export Agriculture, Green Tea, Tea Industrials, Tea Technology