There are numerous studies evaluating biocontrol of root rot by using the antagonistic effects of either
arbuscular mycorrhizal fungi (AMF) or rhizobacteria, but usually independently. Fewer studies, although
growing in number, report on evaluating the effectiveness of concurrent fungiebacteria inoculation in
combating root rot; and furthermore, there are none to date reported with papaya.
In this study, an indigenous Pseudomonas sp. (PPV3) was isolated from roots of papaya (Carica papaya L. cv. Maradol) and used with an AMF complex (MTZ01) consisting of four fungi Glomus intraradices, Glomus mosseae, Glomus
etunicatum and Gigaspora albida to inoculate roots of papaya in order to determine their antagonistic
effects against Fusarium oxysporum, individually and in combination. It was found that with inoculation
with PPV3 and MTZ01 protection was highest (85%) and had reduced disease (10%) as well as reducing
F. oxysporum colonization in papaya seedlings. Inoculations with MTZ01 or PPV3 showed an efficacy of 54
and 60%, with a level of disease severity of the 38 and 22%, respectively. The combination of the AMF
complex (MTZ01) with rhizobacterial Pseudomonas sp. (PPV3) modified the effects of F. oxysporum and
provided increased protection for C. papaya than either acting alone. These results suggest that rhizobacteria
and arbuscular mycorrhizal fungi acting together formed a mutualistic relationship that enhances
disease control against F. oxysporum and stimulates growth in C. papaya.