Relationship between Population Dynamics of Pseudomonas glumae on Rice Plants and Disease Severity of Bacterial Grain Rot of Rice

Abstract

Pseudomonas glumae was isolated from the lower leaf sheaths, stem bases and roots up to maximum tiller number stage. P. glumae populations on the flag leaf sheaths and the 2nd leaf sheaths under the flag leaf sheaths increased during booting stage. And there was a remarkable increase in the bacterial population on spikelets during heading. The higher the number of P. glumae population on rice plants at maximum tiller number stage was, the higher the number of the bacterial population on the upper leaf sheaths and spikelets was. And the higher the number of the bacterial population on spikelets was, the severer bacterial grain rot of rice was. Treatment with oxolinic acid (5-ethyl-5,8-dihydro-8-oxo[l,3]dioxolo-[4,5-g]quinoline-7-carboxylic acid, Starner®) at heading stage inhibited an increase in the bacterial population on spikelets and was highly efficacious in the control of disease. These results suggest that disease severity depends on an increase in P. glumae population on spikelets during heading, and the bacterial population on spikelets is affected by the bacterial populations on the upper leaf sheaths at booting stage, and subsequently the bacterial population colonized on rice plants at maximum tiller number stage. © 1993, Pesticide Science Society of Japan. All rights reserved.