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.