Sour skin (Burkholderia cepacia) is a bacterial pathogen.
Burkholderia cepacia is a gram-negative rod that is 1.6-3.2 m m in length. It was discovered in 1949 by Walter Burkholder at Cornell University in rotting onions. Symptoms usually visible only after onions are dug. Outer layer of scales often becomes darkened and almost orange. Decay of inner scales leads to a soft rot that has a sour, vinegar-like odor.