The present invention relates to a system for controlling the development of fungi during a phytopathogenic attack which enables the plant to express a construct for inhibiting the expression of a gene essential to the development or to the pathogenicity of the fungus. The technology used is based on the mechanism of RNA interference. The present invention provides methods for producing plants resistant to a phytopathogenic fungus, plant cells and plants resistant to a phytopathogenic fungus, and methods of identifying a gene essential to the development or to the pathogenicity of a phytopathogenic fungus.