Methodology for the evaluation of symptoms severity of Mango Sudden Death Syndrome in Pakistan.
Mango (Mangifera indica L.) is an important fruit tree of the tropical and subtropical regions of the world. Presently, the mango orchards in Pakistan are badly infected with the destructive and latent disease, Mango Sudden Death Syndrome (MSDS). The apparent symptoms of this disease are gum oozing, bark splitting, rotting signs, vascular discoloration, canker formation and withered leaves attached over after dying of tree. Methodology for the assessment of mango sudden death in mango orchards was developed in devising a decision support system for timing management of disease. Disease incidence was observed on the collar portion including main roots of infected trees over total number of trees. The disease severity symptoms were recorded on the whole trees i.e., collar region, root zone, main stem, main limbs and leaves from four sides of tree. A disease scale was developed on the basis of visual observations of symptoms on infected mango tree. It comprised of seven scales ranging from 0= no disease sign, 1= 1-10% area of infection over total area observed, 2= 11-20%, 3= 21-30%, 4= 31-40%, 5= 41-50%, 6= 51-60% and 7= 61% to onwards regarded as maximum severity. According to the severity scale for assessment of MSDS, percent disease was calculated as mean value (totalling scale values of each disease symptom observed and dividing them by total number of parameters examined on mango plant) multiplied by 100/maximum scale value. On the basis of this disease assessment method, a sustainable management for mango sudden death syndrome would be devised.