black leg of potato
Figure 1. Often the first symptom of black leg of potato that is noticed is a wilt. 
Figure 2. Initial symptoms of black leg of potato. 
Figure 3. The base of the stem of potato plants affected with black leg is often dark and slimy. 
Figure 4. Base of potato plant affected with black leg. 
Figure 5. Collapse, wilt and dark stems caused by black leg of potato. 
Figure 6. Black leg of potato. 
Figure 7. Dark, slimy stem of potato plant with black leg. 
Figure 8. Black leg of potato may affect only occasional plants. At least initially.