Severity Of Rice Blast Disease Research Articles

Effect of a Multiline of Rice Cultivar Sasanishiki and Its Isogenic Lines on Suppressing Rice Blast Disease.

The effect of the multiline consisting of a rice cultivar, Sasanishiki, and its isogenic lines on the rice blast disease caused by Pyricularia oryzae Cavara was investigated under natural conditions. The blast disease severity and the percent diseased plants in the mixtures were less than that observed in the single line plantings. The blast disease occurrence in the mixture of compatible and incompatible lines was less than that of the compatible lines mixture. Moreover, even in the compatible lines mixture, the rice blast disease severity was depressed significantly. It became apparent that a reduced inoculum density effect and a barrier effect for infection depressed the blast disease, and it was assumed that an induced resistance operated to suppress the blast disease in the Sasanishiki's multiline. Furthermore, the feasibility of using the Sasanishiki multiline of ten isogenic lines with different true resistances was effective for the control of blast diseases.

Remote Sensing of Occurrence Place of Rice Blast Disease by Infrared Thermal Image.

A remote sensing of leaf temperature of rice blast disease was made using an infrared radiative thermometer. The severity of rice blast disease of Hiyokumochi (sensitivity cultivar) was not confirmed by photographs of the visible range taken 19 days after eclosion. The leaf temperature of Hiyokumochi was 1.1°C higher than Reiho (resistant cultivar) using an infrared radiativethermometer. Thus, the severity of rice blast disease of Hiyokumochi was confirmed by infrared thermal image. The leaf temperature difference and disease severity were proportional. The disease severity of rice blast disease (%) = 10.56X2+0.582X-0.295(r=0.999***). Where X was the difference of leaf temperature.

Frequency Distribution of Fields Versus Severity of Rice Blast Disease in a Particular District (Preliminary Note)

Frequency Distribution of Fields Versus Severity of Rice Blast Disease in a Particular District (Preliminary Note)