Abstract
A new and simple method was tested to control tomato bacterial wilt disease caused by Pseudomonas solanacearum. A sheet of compactly woven polyester cloth, which is permeable to water and into which roots cannot penetrate ("root-proof" sheet) is only required. The "root-proof" sheet was placed under the plow layer at a 25cm depth in a heavily contaminated field of a greenhouse. The test plots were sterilized by solar heating during midsummer prior to transplanting tomatoes. In the control plot, all the plants died of the disease within almost one month after planting. In contrast, the plants in the "root-proof" sheet plot were unaffected for almost 4 months throughout the growth period. The effect of solar heating sterilization lasted nearly 320 days up to the terminal stage of the 2nd growth. An improved method was also tested by placing a layer of porous material such as a gravel layer on the lower side of the "root-proof" sheet. No infection of plants was observed in 3 successive full growings of tomato. This observation indicates that the plow layer was protected from recontamination by the elimination of the capillary movement of the soil water from the subsoil.
