Management of Ralstonia solanacearum (Smith) Yabuuchi wilt in tomato (Solanum Lycopersicum L.) with dried powder of the medicinal plant Withania somnifera (L.) Dunal

摘要

The potential of dried powders of leaves, stems and succulent shoots of Withania somnifera (L) Dunal (applied at different rates and at different application timings), was investigated for the control of bacterial wilt (BW) of tomato. In In vitro studies, 15% (w/v) dried powder of leaves produced the maximum (23 mm) zone of inhibition (ZI) followed by the same concentration of dried powder of succulent shoots (i.e., tender shoots plus leaves). The lowest (15 mm) ZI was produced by 5% (w/v) dose of dried powder of stems. The in-planta dose of 30g kg -1 potted soil (succulent shoot powder) applied 20 days before transplanting (20 DBT) was found to be the best treatment combination. It reduced area under disease progress curve (AUDPC), lowered cfu g -1 dry soil, and enhanced plant growth parameters more than the other treatments. The same treatment combination of 30g kg -1 potted soil but applied 10 DBT was the second best combination in terms of disease control or yield-contributing plant growth parameters. The poorest plant growth characters were observed in the treatment combination of 15g/kg soil applied 0 DBT. The AUDPC, and cfu g -1 dry soil were decreased significantly by the treatment combination of 45g (succulent shoot powder) kg -1 soil applied 20 DBT. The plant growth parameters of this treatment combination, however, were lower than those of 30g kg -1 soil applied 20 DBT. This suggested that this dose was probably phytotoxic to tomato plants. As compared to the dried powders of other plant parts, leaf-powder (30g kg -1 soil) enhanced plant growth characters the most, followed by succulent shoot powder. Although the higher dose of 45 g kg -1 soil of leaf powder, like that of succulent shoot powder, declined AUDPC and decreased the cfu g -1 dry soil, it failed to enhance plant growth characters as much as those by other treatments suggesting dose-dependent phytotoxic effect. It is concluded from our data that 30g kg -1 soil of leaf or succulent shoot powder applied 20 DBT can be an effective component of the integrated disease management (IDM) against BW.