Monitoring virulence and sexual compatibility in Brazilian Bremia lactucae populations

Abstract

Lettuce (Lactuca sativa) is among the most widely cultivated leafy vegetables. Its production is in continuous expansion, with an increase of 491,000 tonnes, on average, in recent years (FAOSTAT, 2020). However, Bremia lactucae, the causal agent of lettuce downy mildew (LDM), considered one of the main leaf diseases of lettuce in the world, can infect any stage of plant development and cause extensive production losses (Spring et al., 2018;Van Hese et al., 2016).In Brazil, losses due LDM can reach up to 70% under conducive weather (author's unpublished observations). Disease symptoms include development of light green to yellow areas on the upper side