Identification, pathogenicity and management of <i>Lasiodiplodia theobromae</i> associated with dieback and gummosis of mango in Himachal Pradesh, India

Mango dieback and gummosis threaten mango cultivation in Himachal Pradesh, India. Surveys of 12 orchards (Dashehari cultivar) revealed symptoms like twig discoloration, leaf browning, and gum exudation, with disease incidence ranging from 85% to 100%. A total of 50 different isolates were recovered from affected twigs and gummy exudates. These isolates were identified based on morphological and cultural characteristics. Pathogenicity tests revealed that <i>Lasiodiplodia theobromae</i>, <i>Colletotrichum gloeosporioides</i>, and <i>Fusarium oxysporum</i> are the primary pathogens associated with the disease. <i>Lasiodiplodia theobromae</i> exhibited more than 70% frequency of occurrence in all surveyed locations and was molecularly identified using the internal transcribed spacer (ITS) region. On culture media, <i>L. theobromae</i> produced dark brown, thick-walled, two-celled conidia with a mean size of 30.76 µm × 17.04 µm. Carbendazim showed 87.33% growth inhibition against the major pathogenic fungus <i>L. theobromae</i> followed by captan, thiophanate-methyl, and difenoconazole. Hence, these fungicides are promising for managing mango dieback and gummosis.