Bacterial wilt disease, race 3 biovar 2A, is a devastating disease of potato and other
important solanaceous crops, with no chemical control method. The current studies were,
therefore, undertaken to assess the efficacy of biocontrol agent (BCA) and organic
amendments to manage bacterial wilt (BW) of potato caused by
Ralstonia solanacearum,
under controlled conditions. The present studies evaluated disease severity, latent
infection, arbuscular mycorrhiza fungi (AMF) root colonization and tuber number and
weight on two potato cultivars upon inoculation with AMF, rhizobacteria in various
combinations and organic amendments which included poultry manure, cow manure and
compost. Disease severity was more pronounced in CIP 381381.13 (Tigoni) than in CIP
387164.4 (Clone).
Glomus intradices
+
Bacillus
spp. and
G. etunicatum
+
Bacillus spp.
for both cultivars and for the Clone,
G. intradices +
Pseudomonas
spp.,
Pseudomonas
spp. +
Bacillus spp. +
Azoctobacter
spp. had area under disease progress curve
(AUDPC) of zero. These were also the treatments with the highest AMF root
colonization ranging from 50-36 compared to the controls with zero AMF root
colonization and also tested negative for latent infection test except for
G. etunicatum +
Bacillus spp. in Tigoni. Poultry manure had AUDPC of 33 and 42 in Tigoni and clone,
respectively compared with cow manure with 56 and 43 and compost with 54 and 42 in
Tigoni and clone. A repeat of the trial involving the promising treatments, however, had
all treatments having BW infected tubers. There was no significant difference (P≤0.05)
in tuber number and weight in the BCA treatments with half fertilizer application and
complete fertilized control. Mycorrhizal root colonization ranged from 23-49% in AMF
inoculated treatments while no colonization was observed in the controls. The BCAs
were effective as biocontrols against bacterial wilt even in the susceptible cultivar. More
studies especially under field conditions are needed to further determine the response of
the BCAs and organic amendments under different soil conditions.
