AETIOLOGY, ECONOMIC IMPORTANCE AND CONTROL OF MANGO (Mangifera indica L.) TREE DECLINE DISEASE IN NORTHERN REGION OF GHANA

ABSTRACT This research was conducted from May, 2015 to July, 2016 in the three mango growing districts of the Northern Region of Ghana to obtain baseline information on farmers’ knowledge and perception on prevalence, spread, economic importance and control of mango tree decline disease; determine disease incidence and severity; identify the causal agent(s) of the disease and to develop a chemical control regime for management of the disease. Questionnaire survey and interviews were used to gather information from eighty-four (84) mango farmers selected at random in the three mango growing districts in the Northern Region of Ghana. Disease incidence was determined by counting both healthy and infected mango plant. Disease severity was determined across seven mango farms in each of the experimental communities using a 0 to 5 disease assessment key. Isolation of the causal organism(s) from advancing margins of diseased tissue was done first on Water Agar (WA) and sub-cultured onto a Potato Dextrose Agar (PDA). Identification was carried out using both morphological and molecular techniques. The pathogenicity of three fungal isolates were tested with an incision made on ten months old mango seedlings and mycelia plugs of each isolate inserted singly into the incision made on the stem. There were five mango seedlings per fungal isolate with control. Six fungicides with three levels were evaluated in vitro for their inhibitory effects on mycelial radial growth of the disease causal organism on Potato Dextrose Agar amended with three recommended rates of each fungicide in Completely Randomized Design with three replicates. Field evaluation of three fungicides selected from the in vitro trial was carried out in Randomized Complete Block Design with five plants per fungicide treatment with four replicates. Data was collected on disease incidence and severity before each fungicidal application at two (2) weeks intervals and vegetative growth of plants. The study revealed that, all the farmers (100%) were aware of the occurrence of the mango tree decline disease but were unable to identify  ABSTRACT This research was conducted from May, 2015 to July, 2016 in the three mango growing districts of the Northern Region of Ghana to obtain baseline information on farmers’ knowledge and perception on prevalence, spread, economic importance and control of mango tree decline disease; determine disease incidence and severity; identify the causal agent(s) of the disease and to develop a chemical control regime for management of the disease. Questionnaire survey and interviews were used to gather information from eighty-four (84) mango farmers selected at random in the three mango growing districts in the Northern Region of Ghana. Disease incidence was determined by counting both healthy and infected mango plant. Disease severity was determined across seven mango farms in each of the experimental communities using a 0 to 5 disease assessment key. Isolation of the causal organism(s) from advancing margins of diseased tissue was done first on Water Agar (WA) and sub-cultured onto a Potato Dextrose Agar (PDA). Identification was carried out using both morphological and molecular techniques. The pathogenicity of three fungal isolates were tested with an incision made on ten months old mango seedlings and mycelia plugs of each isolate inserted singly into the incision made on the stem. There were five mango seedlings per fungal isolate with control. Six fungicides with three levels were evaluated in vitro for their inhibitory effects on mycelial radial growth of the disease causal organism on Potato Dextrose Agar amended with three recommended rates of each fungicide in Completely Randomized Design with three replicates. Field evaluation of three fungicides selected from the in vitro trial was carried out in Randomized Complete Block Design with five plants per fungicide treatment with four replicates. Data was collected on disease incidence and severity before each fungicidal application at two (2) weeks intervals and vegetative growth of plants. The study revealed that, all the farmers (100%) were aware of the occurrence of the mango tree decline disease but were unable to identify