Identification and management of vanilla diseases in Madagascar

About 97% of the real vanilla come from Madagascar worldwide. Madagascar’s vanilla is well known for its quality, and its production is very important for the country’s economy. However this culture is threatened by the emergence of fungal and viral diseases that have been recorded for a decade, causing significant devaluations of the production’s level of quality and an important reduction of the quantities annually exported.
In order to be able to scientifically construct a strategy of prevention and control against the main pathogens of vanilla, large sampling campaign was carried out in Madagascar’s SAVA region. Lianas showing symptoms of cryptogamic diseases such as rot, wilt, necrosis or melanosis were harvested. 75 bacteria and 61 fungi were isolated on NA and PDA medium and identified. Morphological and molecular identifications (based on the sequencing of 16S rRNA and ITS regions) of these isolates have shown that the genus Fusarium is the most present (27% of fungal isolates) and is represented by species of F. oxysporum, F. proliferatum, F. concentricum, F. equiseti, F. pseudocircinatum and F. mangiferae. While for bacteria, the genus Bacillus predominates (44% of purified bacterial strains).
Many bacteria of the genus Bacillus are known for their biocontrol properties; this is why we have tested the potential antagonistic effect of all vanilla-isolated Bacillus strains against two species of Fusarium. Nine Bacillus strains were identified for reducing the growth of the fungi, and are of great potential for the development of a biocontrol strategy against Fusarium attacking vanilla in Madagascar.