Three decades of soil solarization: Achievements and limitations

Soil solarization is based on the principle of heating the soil by mulching it with transparent film, thereby controlling soilborne pathogens and weeds. It is a simple, nonchemical and relatively inexpensive method. Soil solarization as we know it today was first introduced in 1976 in Israel. It has since been studied in over 70 developed and developing countries, in hot-climate regions but also to some extent in more humid and cooler regions. It is used by farmers in many countries. It is a preplanting soil disinfestation method that is used with annual crops and to limited extent, trees. As with any new method, soil solarization was introduced in several stages, covering both fundamental and applied aspects: (1) exploring and documenting the method's effectiveness (with respect to a spectrum of pest control) in various regions and cropping systems; (2) studying mechanisms of pathogen control (physical and especially biological) and of crop-growth improvement-models referring to physical and biological processes were developed; (3) integrating soil solarization with nonchemical and chemical (at reduced dosages) means; (4) implementing soil solarization; (5) improving the method and adapting it to various uses; (6) developing extension and training tools. Soil solarization is climatedependent and has advantages and limitations. It has no association with commercial companies, making its dissemination more difficult. Its use has been extended (with appropriate modifications) to purposes other than soil disinfestation, including structural solarization (greenhouses), solar disinfestation of infested tools, production of healthy propagation materials, etc. Multidisciplinary studies, governmental support, knowledge transfer and international cooperation are essential for introducing nonchemical methods of control. Soil solarization, alone or combined with other methods, has become a major alternative in the era of methyl bromide phase out.