Russet Crack and
Internal Cork (virus - Sweetpotato feathery mottle virus): The virus is transmitted
by aphids and it is believed all sweetpotatoes are infected. Symptoms, however,
vary depending on strains of the virus and variety. Russet Crack is associated
with Jersey-type sweetpotatoes. Small, longitudinal cracks encircle parts of storage
rots. Internal cork was once a serious problem, especially in the Puerto Rico
variety. Brown to black corky areas develop in the flesh of roots and can go undetected
until sliced. Modern day varieties are resistant to these two symptoms. Foliar
symptoms vary from purple ring spots to vein clearing.
