fusarium wilt of tomato
Fusarium wilt-One sided wilt is a diagnostic symptom of Fusarium wilt of tomato. An additional symptom is the vascular discoloration that extends many centimeters up the stem. This disease is not common perhaps due to good resistance in modern hybrids.
Figure 1. Fusarium wilt of tomato, as in many other vascular wilts, can cause a one-sided wilt. 
Figure 2. Fusarium wilt of tomato can cause a vascular discoloration on one side of the stem. The one-sided vascular discoloration typically goes along with the one-sided wilt.