Isolation and Screening of Fungal Pathogens and Their Interactive Effect with Weevil [Neochetina bruchi (Hustache)] Against Water Hyacinth [Eichhornia crassipes (Martius)]
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Date
2015-12
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University of Agricultural Science, Dharwad
Abstract
An investigation was carried out to isolate and screen native fungal pathogens from infested water hyacinth plants of Karnataka during 2014-2015. The aquatic weeds exhibiting symptoms like spots, lesions, rots and browning were collected and followed tissue isolation method using potato dextrose agar medium in order to isolate associated fungal pathogens. After a period of four days pure culture of the fungal bio agents was obtained using hyphal tip or single spore isolation techniques and was screened for their disease causing ability on the water hyacinth by spraying with spore suspensions from each fungal isolate, while the control plants were sprayed with sterilized water. Based on the disease severity index three promising isolates viz., Colletotrichum sp., Alternaria sp. and Cercospora sp. were selected for further studies integrating with Neochetina bruchi. In the in vivo experiment, the weevils were introduced to the plants a week before the spray of the fungal pathogens in order to get enough weevil feeding scars to serve as entry point for the fungal spores. Among the different treatment combinations, highest per cent of disease severity and reduced chlorophyll content was recorded with the treatments received dual inoculation of Colletotrichum sp. along with Neochetina bruchi. Furthermore, the treatment received dual inoculation recorded lowest photosynthetic rate and stomata conductance, while the leaf temperature and transpiration rate were found to be increased with the dual inoculation. Thus, our preliminary findings are the indicative of the effectiveness of Colletotrichum sp. along with Neochetina bruchi that can be a promising biotic tool for the management of water hyacinth.
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