Abstract:

To find out an inspection method suitable for primary plant quarantine station in origin area of bacterial stem and root rot of sweet potato caused by Dickeya dadantii, so that the disease can be effectively managed by limited dissemination and spread. The experiments were conducted by several years of field survey of the symptoms development and microscopic observation for the bacterial streaming of 306 stems and 270 other parts samples, and the results were compared and confirmed by traditional and molecular methods. The results showed that the symptom discriminating and microscopic observation for the bacterial streaming can accurately differentiate bacterial stem and root rot disease of sweet potato from other diseases caused by other pathogens. It was the best and effective time for microscopic observation of the bacterial streaming when the water-soaking symptom appeared at base of sweet potato plant in initial stage of the disease. Stem of sweet potato plant was the best position for microscopic observation of the bacterial streaming. The accuracy of initial symptom discriminating and microscopic observation for the bacterial streaming of the disease was more than 98% matched with traditional and molecular tests. It is an accurate, rapid, simple, visible, and suitable inspection method of bacterial stem and root rot disease of sweet potato for extension in primary plant quarantine stations in our country.

Key words: sweet potato, bacterial stem and root rot, Dickeya dadantii, symptom diagnosis, microscope, bacterial streaming