MANGO MALFORMATION DISEASE: ETIOLOGY, EPIDEMIOLOGY AND MANAGEMENT

Abstract

Mango malformation disease (MMD) caused by Fusarium mangiferae severely affects the crop and is widely distributed in almost all mango-growing regions worldwide. Additional Fusarium species have also been reported to cause MMD. Since malformed inflorescences do not bear fruit, MMD is a major constraint to crop production in affected areas. Symptoms of MMD include hypertrophy of young shoots, shorter internodes, dwarfed malformed leaves and an overall tightly bunched appearance of the shoot, while inflorescence malformation include short, thick and branched axes of the inflorescence, larger flowers with increased numbers of male and hermaphrodite flowers that are either sterile or eventually abort. Malformed inflorescences serve as the primary source of spores which disseminate passively in the air as conidia are blown or fall from dry malformed inflorescences as dry debris. Conidia land on the foliage and reach the infection site, namely, the apical bud. Systemic colonization and infection by the fungus was not evident for this host-pathogen interaction, since (i) there was no infection via roots or survival in soil, (ii) there was no continuum of colonization via the vascular tissues, and, (iii) the pathogen is concentrated within apical and lateral buds, only at but not between the nodes. No effective control methods have been reported to date. The airborne nature of dissemination and infection of buds suggests that protection of buds from infection when inoculum prevails may be a plausible method for disease control from season to season. Field experiments conducted over a number of seasons in different experimental regions in Israel indicate that disease severity can be reduced based on sanitation by removing inoculum density within infected panicles and with timely applications of effective fungicides.