APS Homepage

POSTERS: Biological control

Biological control activity of Bacillus sp. RAB14R against rice blast disease and its formulation to increase shelf life
Nootjarin Jungkhun - Chiang Rai Rice Research Center, Rice Department. Donald Groth- Louisiana State Univ Agric Center, Rasamee Dhitikiattipong- Rice Research and Development Division, Rice Department, Inderjit Barphagha- Department of Plant Pathology and Crop Physiology, Louisiana State University, Jong Hyun Ham- Department

Rice blast fungus, Pyricularia oryzae Cavara, is an important disease of rice. Bacillus sp. RAB14R was isolated as a highly antagonistic bacterial stain against P. oryzae. Bacterial suspension of Bacillus sp. RAB14R was sprayed to rice plants at their tillering and heading stages. In the tillering stage of the rice cultivar M202, a highly susceptible cultivar, all forms of Bacillus sp. RAB14R failed to suppress leaf blast. However, the antagonistic bacterium suppressed the disease significantly for a less susceptible rice cultivar CL151, in spite that its disease suppression activity was less than that of fungicide Stratego and there were no significant difference among the different forms of the bacterium. Same pattern was also observed in panicle blast, where Bacillus sp. RAB14R significantly suppressed the symptom development in CL151. Furthermore, long-term survival of Bacillus sp. RAB14R was tested in four different storage conditions: 1) freeze-dried with 5% sucrose, or 2) with 0.85% NaCl and then stored at 4°C, and 3) mixed with talcum powder and stored at 4°C, or 4) at room temperature. Survival rates of RAB14R at the four different conditions were evaluated throughout a 13-month period. After 13 months, freeze-dried bacteria with 5% sucrose showed the highest percentage of viability (~ 20%) among the storage conditions tested, while the bacterium formulated with talcum powder showed less than 10% of survival rate regardless of the storage temperatures.