Blackleg Field Readings
Field tolerance of Blackleg Disease, which is caused by Erwinia carotovora var. atroseptica and E. carotovora var. carotovora, has been excluded from the certification disease list of the Montana Seed Potato Certification Rules and Regulations. This is because environmental conditions and cultivars response to infection can either magnify or suppress blackleg symptom expression sufficiently to prevent a reasonable correlation between the seed reading and next crop grown.