How is the pathogen transmitted?
The bacterium causing Stewart’s wilt can be seedborne or insectborne. At the beginning of a season, bacteria carried by overwintering flea beetles are the major source of inoculum. The proportion of beetles that carry the bacterium varies from season to season and can be as high as 20 percent. Second- and third-generation flea beetles obtain the bacteria by feeding on plants infected with the pathogen by first-generation flea beetle feeding. The larger the second-generation flea beetle population, the more quickly the disease spreads in a season.
