Infection dynamics of Fusarium mangiferae, causal agent of mango malformation disease.

ABSTRACT

Conditions affecting germination and growth of Fusarium mangiferae, causal agent of mango malformation disease, were studied in vitro. Both conidial germination and colony growth required temperatures >5 degrees C and reached a peak at 28 and 25 degrees C, respectively. A minimum 2-h wetness period was required for conidial germination, reaching a peak after 8 h of wetness. High incidence of fungal colonization in buds, predominantly the apical buds, was detected compared with inoculated leaves. The pathogen was detected in the roots of inoculated soil 19 weeks postinoculation but not in aboveground parts of the plants, and symptoms of the disease were not observed, either. Dry, malformed inflorescence debris serving as a source of inoculum caused significantly higher colonization (52 and 20%) of inoculated buds, compared with that (0%) of the untreated controls. Incidence of sampled leaf disks bearing propagules of F. mangiferae from an infected orchard peaked in June and July and decreased during the following months, whereas airborne infections on 1-month-old branches was the highest in May and June, corresponding with inoculum availability released from infected inflorescences. Colonization pattern, determined in naturally infected vegetative and woody branches, was significantly higher in node sections than in the internode sections. This study sheds light on infection dynamics, colonization patters, and the disease cycle of F. mangiferae in mango.