Physical and biochemical integrated management using soil solarization and chitin or chitosan singly or in combination for controlling tomato wilt disease under field conditions was studied. Chitin had no inhibitory effect on the growth of pathogenic fungus. On the other hand, chitosan at 6 g LG1 completely inhibit the linear growth and spore germination of F. oxysporumf. sp. lycopersici. Under field conditions, results indicated that maximum soil temperatures in solarized were recorded 55.2, 50.8 and 46.3°C at depths of 1-10, 11-20 and 21-30 cm of soil surface. Solarization was more effective in reducing the pathogen population. The highest reduction in total count of F. oxysporum f. sp. lycopersici was observed in mulched soil at 1-10 and 11-20 cm depths. Soil solarization and chitin at 6.0 g kg-1 soil, chitosan at 6.0 g kg-1 soil or topsin at 3.0 g kg-1 soil singly or in combination for controlling tomato, wilt disease under field conditions was evaluated. Results revealed that all treatments significantly reduced the disease incidence and severity during two growing seasons. The highest reduction in disease incidence and severity were obtained with combined treatments between soil solarization and chitin, chitosan or topsin which recorded 3.2-5.0% as disease incidence and 0.2-0.3% as disease severity during two growing seasons. As for tomato yield the highest increase in tomato yield was obtained with combined treatments between soil solarization and chitin, chitosan or topsin which increased the tomato yield more than 66.7, 68.9 and 66.7% during two growing seasons. All treatments significantly increased the chitinase activity of tomato plants. The most effective treatments were combined treatments between soil solarization and chitin or chitosan which increased the chitinase activity by 100.0 and 116.7%. It could be suggested that combined treatments between soil solarization and chitin or chitosan as safety materials might be used commercially for controlling tomato wilt diseases under field conditions. |
