Malformation presence in mango seedling trees cultivated within infected Egyptian orchards

Mango malformation, caused by the fungus Fusarium mangiferae, is one of the major diseases of mango, it occurring worldwide and causing significant economic loss due to the general incapacity of malformed inflorescences bearing fruits. This study was conducted to for the purpose of gaining an understanding of certain aspects of epidemiology, survival and spread of the pathogen in general and specifically in seedlings, the majority of which, in Egypt, are cultivated in infected orchards. After 16 weeks, the pathogen survived in approximately 88% of infected panicles buried in soil, whereas populations were not detected in material placed upon the soil surface. Vegetative malformed mango seedlings growing under infected mature trees and infected panicles were sampled in two locations in Egypt, to determine distribution of the pathogen within plant tissue. Presence of the pathogen was detected by plating on a Fusarium-specific medium and verified by PCR-specific primer amplification. With PCR, the pathogen was detected in 97% of the seedling apical meristems, declining gradually to 5% colonization in roots. Based on this study, it would appear that inoculum of the pathogen originates from infected panicles and affects seedlings from the meristem, with infections descending from top to lower stem sections and roots. The results indicate the potential applicability of species-specific primers for early detection and identification of F. mangiferae in infected tissue.