Abstract:
Banana (Musa sp) is an important fruit crop cultivated throughout the
year and is the traditional mainstay of Northern Sri Lanka’s livelihood.
Occurrence of pests and diseases is the major constraint in banana cultivation
and Marasmiellus stem rot is a recently reported fungal disease to banana fields in
northern region. A study carried out in 2010-11 revealed that the disease was
found spreading slowly among the banana growing areas in Jaffna peninsula,
because of the threat imposed by this disease it should be checked at the initial
stage. This in vitro study aims to screen locally available fungicides to develop
control measures for the stem rot of banana. The fungus was isolated from the
diseased banana plants and pure culture was maintained in potato dextrose agar.
Five broad spectrum fungicides at two levels of concentrations as manufacture
recommended level and half of the recommended level were evaluated, using
poison food technique, against the radial growth of mycelia of Marasmiellus sp
(Basidiomycetes: Agaricales: Tricholomataceae) isolated from diseased banana. It
was observed that these fungicides Copper 50% (w/w) WP as copper
oxychloride (Coblite), Thiram 80% (Pomarsol forte WP 80%), Captan
50%(w/w) WP (Captan), Metalaxyl 8% (w/w)+Mancozeb 64% (w/w) WP
(Ridoaxyl) and Chlorothalonil 75% (w/w) WP (Max) at both concentrations
inhibited mycelia growth of the fungus. All fungicides significantly differed from
the control except Coblite. The highest percentage inhibition was recorded as
86.76% (11.92 mm Mean Colony Diameter (MCD)) from the manufacture
recommended level of concentration (0.5g/100ml) of Metalaxyl 8% (w/w) +
Mancozeb 64% (w/w) WP indicating combined effect of two compatible
fungicides, followed by Chlorothalonil at both concentrations 0.15g/100ml and
0.075g/100ml were inhibited 64.09% (32.32 mm MCD) and 61.02% (35.08 mm
MCD) of colony growth respectively. This investigation revealed that, Mancozeb
and Metalaxyl in combination and Chlorothalonil based fungicides can be the
best option for effective control of Marasmiellus sp. and prevent further spread of
the banana stem rot from suspected areas and also best method to treat planting
material at planting. However; field level investigation has to be carried out to
confirm the application.
