For a few years, in France, Orobanche ramosa L. (broomrape) has become a real agronomic threat in three important industrial crops: winter rape, tobacco and hemp. In 2003, it was observed parasitizing tobacco and hemp and 22 out of the 96 French departments were infested. On tobacco, seven out of the eight French co-operative societies were concerned by broomrape with 0.2 to 17.7% of the tobacco acreage infested. To obtain a better understanding of the parasite biology, the broomrape cycle of development was determined on the tobacco variety Virginia ITB 31612 during 2002, and compared during 2003 and 2004. During 2003, the warmest year, broomrape developed more rapidly. So, the parameter "sum of temperatures" was considered and it appeared correlated with parasite stages of development. In parallel, differences of susceptibility were observed between this tobacco variety and three others, two Virginia (ITB 33024 and ITB 3304) and one Burley (ITB 501). Unfortunately, no resistant variety was identified. Among control methods tested against broomrape in tobacco fields by ANITTA (National Tobacco Technical Center), the use of maleic hydrazide was the most promising one. In 2003, after a tobacco foliar spray with this systemic herbicide, O. ramosa spikes were harvested and the germinative power of broomrape seeds and their viability were tested in vitro . The application of 3000 g a.i. ha^-1 of maleic hydrazide drastically decreased the viability of broomrape seeds by 65%, without any significant phytotoxicity for the crop. During 2005, this treatment was tested in a program for the registration of Perlot, a commercial formulation of maleic hydrazide, against O. ramosa in tobacco fields. Results showed the same tendency as in 2003, an amount of 3000 g of a.i ha^-1 could decrease the viability of seeds by about 80%.