Black Shank Control

Black shank can cause significant losses in South Carolina tobacco. Black shank is caused by a fungus (Phytophthora parasitica var. nicotianae), which lives in the soil and attacks the plant primarily through the roots. Wounds are not required for infection by the black shank fungus. High soil moisture favors root colonization by the black shank fungus, although effects of early season infections become most apparent when soil moisture becomes limited. Sustaining high disease losses from black shank is tragic, because we know that rotation is very effective in reducing levels of the fungus in the soil. Any rotation is effective to some degree, because tobacco is the only host of the black shank fungus. The longer the rotation, the more effective the control. Therefore, rotation is the backbone of a successful control strategy, which also should utilize resistant varieties, chemicals and cultural practices.