ABSTRACT
Control Research in California indicates that commercial lettuce seed is infrequently infested with this pathogen. In addition, infestation thresholds have not been established for seedborne inoculum of this disease. However, if seedborne inoculum becomes important, use seed that does not have significant levels of the pathogen. Examine lettuce transplants and remove symptomatic plants. Reduce or eliminate overhead sprinkler irrigation in the production field. Some resistant cultivars are available. Do not plant consecutive lettuce crops, and use crop rotations having non-host plants so that soilborne inoculum levels can decline. Copper based fungicides appear to provide only marginal control. References Barak, J. D. and Gilbertson, R. L. 2003. Genetic diversity of
Xanthomonas campestris pv. vitians, the causal agent of bacterial leafspot of lettuce. Phytopathology 93:596-603.
