Lettuce is one of the most important leafy vegetables grown in Brazil. However, intensification of its production has led to increased difficulty in cultivating this vegetable, especially due to infestation of producing areas with the phytopathogen Bremia lactucae Regel, the causative agent of downy mildew, one of the worst diseases affecting lettuce. The aim of this study was to identify B. lactucae races in 2010 and 2011 in major lettuce producing cities in the state of Sao Paulo. Thus, leaves with sporangia of B. lactucae were collected from lettuce producing cities and each sample was considered an isolate, totaling 56 and 96 in 2010 and 2011, respectively. The collected sporangia were multiplied in the susceptible cultivar Solaris, with subsequent inoculation into the differentiating cultivars, and evaluations were performed on the same day of the onset of the first sporulation in the susceptible cultivar 'Green Tower' (DM 0). In 2010, a new code of B. lactucae in lettuce was identified (63/31/03/00), corresponding to a new race to which the name SPBl:07 was proposed. In 2011, two other codes of B. lactucae were identified (31/63/9/00 and 31/63/51/00), to which the names SPBl:08 and SPBl:09 were proposed, respectively.
Lactuca sativa L.; genes DM; downy mildew; resistance
