Application of drainage on disease management of water spinach bacterial wilt caused by Ralstonia solanacearum.
A total of 63 varieties of water spinach (Ipomoea aquatica) were screened for resistance to bacterial wilt by clipping off the stem apex with scissors dipped with suspension of Ralstonia solanacearum (107 cfu/ml). None of the tested varieties was resistant to bacterial wilt. The disease could be reduced significantly by proper management of the irrigation water. When the paddy field was well drained and dry for 14, 21 or 28 days after each harvest, the pathogen infection rate of the survived plants were 4-14% compared with 42% of the non-drained treatment. After the field was irrigated again, the survived plants grew quickly, and the disease incidence was reduced to 2.2-10.8% compared with 38.5% of the non-drained treatment at the harvest. The yield of water spinach also increased significantly by the drainage treatment, and the cultivation period of each harvest was extended to 32-42 days for the drainage treatment than the non-drained treatment.