Southern bacterial wilt
Host: flue-cured tobacco (Nicotiana tabacum (flue-cured type)
(except Race 3 Biovar 2) (Smith 1896) Yabuuchi et al. 1996
Description: The first symptom of this bacterial disease is the drooping of one or two leaves which may recover at night. Only half of a leaf may wilt initially. Leaves on one sides of the plant wilt first, while leaves on the other side appear normal. This unilateral wilting is very characteristic. Affected leaves become light green to yellow and occasionally appear scaled. Eventually most or all of the roots become blackened and decay. Infected roots become soft and slimy if adequate water is present. Tan or brown discoloration develops in the vascular tissue just beneath the bark. Pith and cortex also become discolored when involved. Longitudinal sections through affected stalks have narrow, brown lines in the xylem tissue nearest the pith. A slimy substance often oozes from a stalk cut in cross section. If a stalk segment containing discolored vascular tissue is placed in a clear container of water, milky strands stream from the edge of the tissue.
Image type: Field
Image location: United States
Name: Clemson University - USDA Cooperative Extension Slide Series
Country: United States