Spatiotemporal distribution of barley and wheat plants naturally infected with bacterial black node in fields in western Japan

Bacterial black node caused by Pseudomonas syringae pv. syringae is the most serious bacterial disease of barley and wheat in Japan. The spatiotemporal distribution of barley and wheat plants infected with bacterial black node in fields in 2016–2017 was analyzed using Taylor’s model and Iwao’s model. In Taylor’s model, the sample variance (s2) of the total and the newly diseased plants at each observation increased with mean plant density (m). In Iwao’s model, although the mean crowding (m*) of total and newly recognized diseased plants increased with m, Taylor’s model fit the data better than did Iwao’s model. Thus, bacterial black node could be explained as a colony expansion model.