A 9-year monitoring study of diseases on potato seed tubers imported to Israel.
Potato seed tubers are imported annually to Israel from northern Europe. Although the seed is registered as certified, a survey carried out during 1985-92 indicated that most lots were affected by latent or active bacterial and fungal infections. Latent infection by Erwinia carotovora subsp. atroseptica at 103 cells/g peel was present in 30% of the lots in most years. Black scurf (Rhizoctonia solani) was present in 20-70% of the imported lots, with a moderate to high level of infection in all years except 1985. Although many lots were affected by powdery scab (Spongospora subterranea), common scab (Streptomyces scabies) and Fusarium dry rot in most years, disease incidence within lots was generally low. The gangrene pathogen Phoma exigua was rarely detected. It is concluded that these findings are of marked importance for controlling tuber infection of potato due to the extensive use of soil fumigation in Israel.