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Subject: Plant Pathology × Author: Bokotial, Pinkumoni × Start date: 2020 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    MICROBE BASED MANAGEMENT OF CITRUS CANKER DISEASE vis a vis PREVAILING WEED FLORA
    (AAU, Jorhat, 2021) Bokotial, Pinkumoni; Nath, Bharat Ch.
    Citrus canker disease as well the weed flora of citrus grove decrease the quality and quantity of the citrus fruit. An eco-friendly approach for management of Citrus canker disease vis a vis prevailing weed flora was attempted using bioactive microorganisms, Pseudomonas fluorescens and weed pathogens. In the assessment of weed composition, two weeds, Alternanthera philoxeroides and Commelina benghalensis were found to have highest population density of 83% and 25% in the field condition with visible disease symptoms. From the cultural and morphological study of these two isolates, they showed their similarity with Nimbya alternantherae and Colletotrichum siamense. The molecular characterization of these microorganisms was made to determine their distinctiveness from their close relatives through sequencing of ITS region of ribosomal DNA.Interactive action of these two weed pathogen with P. fluorescens resulted in the partial compatibility of P. fluorescens with Nimbya alternantherae and incompatibility reaction in all other possible treatment combinations in vitro. The antagonistic potential of these compatible microbes was tested in vitro singly or in combination and per cent inhibition of target pathogen, Xanthomonas citri pv. citri were recorded and analyzed. Highest inhibition (30.00 %) of X. citri pv. citri was recorded against P. fluorescens and N. alternantherae followed by P. fluorescens (18.52%) in vitro. In the field study, highest citrus canker disease reduction (21.85%) was recorded in the treatment of P. fluorescens followed by treatment comprising of P. fluorescens and N. alternantherae (14.61%). In case of management of Alternantherae philoxeroides weed in field condition, highest percent disease increase (77.49% in manual analysis and 69.98% in AI analysis) was recorded against treatment of N. alternantherae followed by treatment comprising of P. fluorescens and N. alternantherae (41.63% in manual analysis and 45.95% in AI analysis). Correlation studies revealed positive linear relationship between manually and AI analysed data.