Water-soluble granules containing Bacillus megaterium for biological control of rice sheath blight: formulation, bacterial viability and efficacy testing

Abstract

Endospores of B. megaterium were formulated in granule formulations with sodium alginate, lactose and polyvinylpyrrolidone (PVP K-30) by the wet granulation technique. The granule formulation exhibited good physical characteristics, such as high-water solubility and optimal viscosity, that would be suitable for spray application. The bacteria remained viable in the dry granule formulation at 10 9 c.f.u./g after 24 months storage at room temperature. Under laboratory conditions, aqueous solutions of the formulation showed high activity against mycelial growth of R. solani (99.64 ± 0.14% mycelial inhibition). High viability of the bacterial antagonist on leaf sheath and leaf blade at day 7 after spraying with the formulation was observed (approximately 10 6 c.f.u./g of plant). Application of an equivalent number of un-formulated endospores resulted in much loss of the bacterial endospores even 1 day after application. In a small pilot field study, an aqueous solution of the formulation (3%w/v) applied by spraying at days 1, 5 and 10 after pathogen inoculation of the rice plants was more effective in suppressing rice sheath blight disease than one application of a fungicide (Iprodione) at day 1. Additionally, rice plants sprayed with the aqueous solution of the granule formulation had higher panicle and whole kernel weights than those of fungicide-treated and control (untreated) plants.

Spray-dried powder ofBacillus megateriumfor control of rice sheath blight disease: Formulation protocol and efficacy testing in laboratory and greenhouse

“…A suspension of B. megaterium endospores was prepared as described by Chumthong et al (2008). The bacterium was cultured in potato dextrose broth (PDB) at 30-35 °C, stirring at 200 rpm for 4 days, and bacterial cells at the stationary growth stage were separated by centrifugation at 3,000 rpm for 10 min.…”

EXAMINATION OF CHITINOLYTIC BACTERIA IN ALGINATE-CHITOSAN ENCAPSULATION ON CHILI SEED AGAINST DAMPING OFF CAUSED BY <i>FUSARIUM OXYSPORUM</i>

“…Vegetative cells are more susceptible to environmental stress compare to endospores. However, Chumthong et al (2008) observed that application of an equivalent number of un-formulated endospores resulted in much loss of the bacterial endospores even 1 day after application. Furthermore chili bead producing by method described seemed not to uniform.…”

Application of a suspension concentrate formulation of <i>Bacillus velezensis</i> to control root rot of hydroponicallygrown vegetables

“…In Thailand, research on the use of biological control to suppress plant pathogens has been carried out with damping-off of cucumber Diseases of crops & vegetables (Intana 2003), leaf blight of bambara groundnut (Pengnoo et al 2006) and sheath blight of rice (Wiwattanapatapee et al 2004;Wiwattanapatapee et al 2007;Chumthong et al 2008). Some of these studies have led to the commercialisation of the biological control agent, Trichoderma harzianum (Intana 2003) for control of soil-borne plant pathogens.…”