Biofumigation for the management of damping-off in greenhouse cucumbers in the sultanate of Oman

Damping-off, caused by Pythium aphanidermatum has become a major problem in the greenhouse crop sector in Oman. in attempts to combat the disease, farmers use fungicides, often indiscriminately, often excessively, usually unsustainably. Disease misdiagnosis is frequent and inappropriate fungicide applications are common. Biofumigation is a potentially valuable alternative to fungicide use. Organic matter is incorporated into the top levels of the soil which is then covered with clear plastic for 4 weeks; breakdown releases ammonia gas which fumigates the soil. Biofumigation and conventional solarization have been tested in Omani greenhouses during the summer fallow period and between cool-season crops. Cabbage residue was used at the rate of 5 kg per m row length. Solarization was performed by covering the greenhouse soil for a period of 4 weeks. Both treatments reduced P. aphanidermatum inoculum levels in soil relative to the control. When used in the summer period, solarization and biofumigation both achieved a substantial reduction in damping-off incidence. in the cool season, biofumigation was more effective in reducing damping-off. Both treatments reduced the number of primary disease foci and both reduced the rate of secondary expansion of foci.