Abstract
An investigation was made to estimate the damage of Cercospora leaf spot caused by Cercospora beticola Sacc. in sugar beet, Beta vulgaris var. rapa Dumot. The disease in field grown sugar beet plants was controlled by spraying with copper fungicide and therefore this chemical was used for establishing different degrees of damage.
When the seeds were sown in the Tohoku district in late April, the damage was most severe at forty leaves stage of the plant. At the stage, generally, the top growth of the plants was most vigorous. When the infection was severe, the plants showed severe defoliation and reduction of the vigorous leaves. As the result, reduction of root growth yield and sugar content were corresponded.
When the infection occurred after forty leaver stage of the plants, the damage was not so severe.
