Effect of downy mildew on EcO157 and
Typhimurium population dynamics on romaine lettuce (cultivar Green Towers) leaves over time after inoculation and incubation of the leaves under conditions of warm temperature and presence of free water on the leaves. Population sizes of EcO157 (▲) and S. Typhimurium (■) were assessed on leaf discs of healthy (dotted lines) and B. lactucae-infected necrotic (solid lines) lettuce tissue. Data points represent the mean of log-10 (cfu per disc) for three replicate discs sampled from different leaves. Error bars indicate standard error of the mean.