EFFECT OF PREVIOUS CROP ON SOIL POPULATIONS OF BURKHOLDERIA-SOLANACEARUM, BACTERIAL WILT, AND YIELD OF TOMATOES IN TAIWAN

Three field experiments were conducted to evaluate populations of Burk holderia solanacearum and the occurrence of tomato bacterial wilt in s oil left fallow, and following crops of cowpea, eggplant, and rice. Ba cterial population declined after cowpea and rice, but not after eggpl ant. The population also declined after soil was left fallow, indicati ng that a suitable host plant is required to maintain the bacterial po pulation. The area under disease progress curve (AUDPC), based on the incidence of wilted tomato plants, was significantly (P < 0.05) higher following eggplant compared with cowpea and rice for three experiment s and in fallow for two of the three experiments. Yields of cowpea, eg gplant, and rice were not affected by the presence of B. solanacearum in the soil; however, yields of tomato crops were significantly (P < 0 .05) lower following eggplant than following rice. Under greenhouse co nditions, bacterial populations decreased more when soil was cropped t o rice under permanently flooded conditions.