Pathogenicity of branched broomrape ( Orobanche ramosa ) populations on tobacco cultivars

Parasitic weed species of the genus Orobanche are a serious threat for the production of several crops in Europe, Africa and Asia. In contrast to other broomrape species of agronomic importance, O. ramosa (branched broomrape) has a broad host range and in Europe particularly affects hemp, tobacco, tomato and, in recent times, oilseed rape. Two separate sets of experiments investigated the effect of two populations of O. ramosa on nine tobacco cultivars grown in Europe and belonging to the three major tobacco types: Virgin (flue‐cured), Burley (light air‐cured) and dark air‐cured under standardized glasshouse conditions. The two broomrape populations were discriminated by means of polymorphic DNA fragments obtained by PCR of the intersimple sequence repeat regions (ISSRs). The Orobanche populations exhibited different levels of pathogenicity but all various tobacco cultivars were susceptible. Dark air‐cured tobacco cultivars were the least susceptible to both broomrape populations. Virgin and Burley tobacco cultivars were more susceptible to one population of O. ramosa .