Author(s):

Padamini Rajkumari and Bireswor Sinha

Abstract: Natural incidence of Rhizome rots of ginger at five different districts of Manipur during July and September 2016 showed higher disease incidence in hill districts viz., Tamenglong, Churachandpur and Bishnupur where shifting cultivation has been practiced. Among these the highest was recorded in Tamenglong with disease incidence of 16.51% during July and 38.62 % during September 2016. Whereas in plains Imphal East district showed higher disease incidence of 10.79% in July and 29.22% during September as compared to Imphal west district which showed 08.89% during July and 25.39% during September 2016. Isolation of the biocontrol agent was done from the air-dried rhizosphere soil of healthy ginger leaves and rhizome using selective media. The studies resulted in recovery of those organisms which are known to act as biocontrol agents of plant pathogens. The isolated cultures of Trichoderma spp. were identified as six isolates of Trichoderma asperellum, six isolates of T. harzianum, one isolate each of T. hamatum and T. longibrachiatum. Maximum growth and sporulation of isolates of Foz was recorded at a temperature of 30⁰C with pH 7. The antagonism test showed that 78% of the Trichoderma isolates strongly invaded Foz in vitro (rating =1 or 2). 47% had a rating of 1, 25% had a rating of 2, 15% had a rating of 3, 9% had a rating of 4 and 4% had a rating of 5. Comparison between the population densities of most potent Trichoderma isolate (T. harzianum-MH259837) and Fusarium oxysporum f.sp. zingiberi in ginger field at plains and under jhum cultivation was carried out. The initial population 6.8 × 10⁵ c.f.u /g seed for T.harzianum-MH259837 and 2.4× 10⁶ c.f.u /g soil was recorded. The result showed that among the different substrate tested for mass multiplication of T. harzianum-MH259837 in plains at 30 DAS highest population densities was recorded in treatment with rice bran + T. harzianum-MH259837 (6.5 × 10⁵ c.f.u /g soil). The success of a biocontrol agent depends much on the establishment of the product, the formulation and delivery system. The production of propagules can be carried out in liquid or solid fermentation. The maximum biomass production is influenced by aeration, agitation, pH, and temperature. It has been reported that the formulation used to introduce Trichoderma in soil influences rhizosphere competence. Agricultural wastes that have been reported to be good substrates as a result rice bran was found to be the most suitable substrate and highest spore count was observed for BCA.

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