ANTIBACTERIAL ACTIVITY OF CERTAIN PLANT EXTRACTS AGAINST BACTERIAL WILT OF TOMATO. K. Abo-Elyousr (1), A. M. Asran (2) and W. Zeller (3)
(1) Plant Pathology Dept. Faculty of Agriculture, Assiut University - 71526, Assiut, Egypt; (2) Dept. of Plant Pathology, Faculty of Agriculture, Sohag Univ., Sohag, Egypt ; and (3) Julius-Kühn-Institut, Bundesforschungsinstitut für Kulturpflanzen, Institut für biologischen Pflanzenschutz, Heinrichstr. 243, 64287 Darmstadt, Germany.

Abstract: Five isolates of Ralstonia solanacearum were isolated from a naturally wilted root of tomato plants grown in Assiut governorate of Egypt. The antibacterial activity of plant leaf extracts of Datura, Garlic and Nerium were tested in controlling R. solanacearum in vitro and in vivo. Garlic extract exhibited the strongest antibacterial activity against bacterial wilt in vitro and in vivo followed by Datura and then Nerium. Cold water extract of these plant species were more effective than hot water extract in the development of the disease in vivo. In greenhouse experiments, the application of the tested plant extract to soil at the time of inoculation, two days before inoculation and two days after inoculation with the pathogen, significantly reduced the disease index of wilt on tomato cultivar Super Marmande. The application of plant extracts at the same time of inoculation resulted in the highest reduction of disease index.