Epidemiology and management of anthracnose of bottlegourd caused by colletotrichum lagenarium (Pass.) ellis and halsted
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Date
2006
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Publisher
CCSHAU
Abstract
In epidemiological studies on the development of anthracnose of
bottlegourd caused by Colletotrichum lagenarium emphasis was on the
initiation and progression of the disease in relation to the weather
variables and spore load in the field. The present study revealed that
the severity of the disease increased with the increase in inoculum load
and it was observed that spore concentration of 105 spore/ml produced
maximum disease severity (31.05%). Age of the leaves also played an
important role in the development of the disease as disease severity
increased in leaves upto the age of 35 days thereafter it declined. Leaf
wetness for 24 hours provided maximum disease severity (62.92%),
whereas leaf wetness beyond 24 h had further no effect on severity.
Relationship has also been worked out on spore population,
weather parameters and disease development. Disease development
was directly proportional to the spore production in the field. Further,
temperature (maximum) in the range of 34-34.60C, temperature
(minimum) 17.5-18.80C, relative humidity (morning) 82-92 per cent
and relative humidity (evening) 29.6-47.7 per cent were congenial for
both spore production and disease development. The regression
coefficient of the disease severity and spore population with weather
parameters revealed that temperature (minimum) and relative humidity
(evening) are major contributing factors which could predict 88 of
disease and 58 per cent of the spore population respectively. It was also
seen that the observed values of disease intensity and spore population
were close to the predicted value.
The effect of bioagents on mycelial growth of Colletotrichum
lagenarium by dual culture technique revealed that Trichoderma viride
gave maximum inhibition of 59 per cent. Among various plant extracts
evaluated for spore germination inhibition, neem leaf extract gave
maximum 58.43 per cent inhibition. Similarly by poison food
technique, neem extract gave maximum inhibitory effect on the
mycelial growth (79.43%) of the fungus, which was at par with
mancozeb at 0.1 per cent concentration. Under field condition foliar
spray with neem leaf extract at 50% concentration gave significantly
higher disease control (79.2%) as compare to control and it was at par
with mancozeb (0.1%).
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Keywords
Bottlegourd, Anthracnose, Colletotrichum lagenarium,Epidemiology, Management, Plant extracts, Bioagents