Characterisation And Control Of Xanthomonas Campestris Pv. Mangiferaeindicae Causing Mango (Mangifera Indica L.) Bacterial Black Spot Disease In Some Selected Districts Of The Eastern And Vol

ABSTRACT

Mango bacterial black spot disease is one of the most devastating diseases of mangoes worldwide. The disease was observed in some mango orchards in the Lower Manya and Asuogyaman districts of the Eastern region and North Tongu district of the Volta region of Ghana. The objectives of this study were to assess farmer’s perception and knowledge on the prevalence, spread and economic importance of the mango bacterial black spot disease, determine the disease incidence and severity in mango farms, assess the effect of the disease on yield/fruit quality confirm if the causal agent of the current outbreak of the disease in the study area is Xanthomonas campestris pv. mangiferaindicae and evaluate some selected fungicide/bacteriocides for control of the disease in the field. Questionnaires (60) were administered to randomly selected farmers who were actively engaged in mango farming in the study areas. These were read out and interpreted to farmers when necessary for clarity. The questionnaires covered the general background of the farmers and their perception and knowledge concerning the cause, importance, spread, and control of the disease. Data collected were analyzed using descriptive statistical analysis (means and percentages). Disease incidence in the study area was determined by expressing number of infected trees s a percentage of total number of trees inspected while disease severity was determined by rating the percentage of fruit area disease on a scale of 0-5 where 0=no disease and 5=more than 50% of fruit area diseased. Data obtained was presented by calculating means and standard errors. The suspected causl agent of the disease was isolated from diseased mango fruits and identified using morphological characteristics, biochemical reactions and molecular methods. Detached mango leaves of kent variety were inoculated with a bacterial suspension of 1.0×106CFU/mL using the needle prick method to confirm pathogenicity. The effect of the disease on yield/fruit quality loss of mango was determined on different mango cultivars, namely Keitt, Haden, and Palmer. In vitro

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evaluation of the inhibitory effect of some copper based fungicides on the growth of Xanthomonas campestris pv. mangiferaindecae was evaluated using the disc fusion method. The treatments were then evaluated on the field using randomised complete block design with three replicates. Farmers in the study areas demonstrated good knowledge of the disease. The disease incidence ranged from 27% in Asuogyaman District to 90% in the North Tongu District, while severities were 0.5 to 3.0 in th same districts. The disease caused a fruit quality/yield loss of 71.5% and the pathogen was confirmed as Xanthomonas campestris pv. mangiferaeindicae based on cultural, morphological, and sequence analysis of the cpn60 gene. Copper hydroxide completely inhibited the growth of the bacterium in the in-vitro studies while metallic Copper+Mancozeb (Cuprofix-30 disperse) effectively reduced the disease incidence and severity in the field.