Grafting local commercial tomato cultivars with H-7996 and Eg-203 to suppress bacterial wilt (Ralstonia solanacearum) in Indonesia

Bacterial wilt of tomato (Ralstonia solanacearum) causes serious losses of tomato production in Indonesia. Currently, proper cultural practices are the only way performed by farmers to combat the disease. While this practice could not effectively prevent infection of R. solanacearum to the plant, efforts have been sought to help farmers keep their plants away from bacterial wilt. Grafting of commercial cultivars with available rootstocks is easy to perform and the effectivity of this method in suppressing tomato bacterial wilt has been reported in many countries but not in Indonesia. The objective of this study was to find out whether grafting susceptible commercial cultivars of tomato with resistant rootstocks could suppress the development of bacterial wilt in Indonesia. The grafting was conducted in Yogyakarta region, Indonesia, in 2011 with H-7996 and Eg-203 as rootstocks and three commercial cultivars of tomato (‘Permata’, ‘Lentana’, and ‘Fortuna’) as scions. The results indicated that the rootstocks could afford the existence of population of pathogen in the stem tissue, exhibit lower disease index compared with mock grafted and non-grafted plants. The pathogen could be detected in the stem tissue above soil surface at 21 and 28 days after inoculation in plants grafted with H-7996, but it was detected in non-grafted and in mock grafted plants just in 7 days after inoculation. At 35 days after inoculation the pathogen population in the stem tissue (2 cm above ground) varied from 103 (plants grafted with Eg-203) to 109 (mock grafted plants and non-grafted plants) cfu/5 mm tissue. The grafted plants exhibited lower disease index, better growth and yield compared with those of mock grafted and non-grafted plants. The result suggests that grafting commercial cultivar tomatoes with either H-7996 or Eg-203 could suppress bacterial growth, bacterial wilt incidence, and enhance fruit production.