The surname Nguyen is believed to have originated in the Chinese surname Ruan (in the Mandarin language) or Yuen (Cantonese), owing to Chinaâs long domination over Vietnam.
Tinea nigra is a fungal infection that is mainly seen on the palms of the hands or soles of the feet causing a dark brown to black discoloration of the affected skin. The word tinea means a fungal infection and nigra means black.
Black rot is caused by the fungus Ceratocystis fimbriata. The disease can cause significant losses in storage, in the transplant bed, and in the field. The pathogen not only reduces yield and quality but also gives sweet potatoes a bitter taste. Small, circular, slightly sunken, dark brown spots are the initial symptoms of black rot (Figure 1).