Main Symptoms

Like many other vascular diseases and as its name implies, this disease is characterised by often unilateral, foliar wilting, sometimes accompanied by yellowing (figure 1). The affected tissues rather quickly become necrotic and dry up. Cutting a longitudinal section of the stem reveals that the vessels have turned brown and that the lesion may have penetrated the pith and cortex (figures 3 and 4).

Some of the information on the worldwide distribution of the disease is obtained from surveys conducted by CORESTA (Cooperation Centre for Scientific Research Relative to Tobacco). The reliability of the information is not confirmed in all countries.

U.S. situation

Can Bacterial wilt be identified in a field without removing a plant from the soil?

Frequently agronomists ask how they could identify bacterial wilt in a tobacco field without removing plants from the ground. The following could be suggested: a. look for wilted plants, if possible identify which side is wilted (not always obvious at first look); b. observe the stalk(stem) at the soil line on the wilted side if there is a black lesion; c. cut the outer bark above the black lesion and see if there is streaking. This is a good way to separate also bacterial wilt from black shank without destroying many tobacco plants.

(Mina Mila - North Carolina State University)