Morse Code Symptom
  • BBTD is diagnosed by identifying symptoms of diseased plants or by submitting a banana leaf sample for virus testing
  • The so-called "Morse code" symptom is a subtle but reliable indicator of Banana Bunchy Top Disease (BBTD)
  • The Morse code symptom is a series of dark green dots and dashes seen along banana veins in a BBTV-infected leaf or petiole infected by the banana bunchy top virus (BBTV).
  • To best view this symptom, hold the banana leaf between your eyes and the sun (with the bottom side of leaf facing you), and allow the diffuse sunlight to be transmitted through the leaf to reveal the Morse code dots and dashes. Sometimes transmitted light is not needed in order to see the symtpom.
"Morse code" Streaking on BBTV-Infected Banana Leaves and Petioles the Veins Have "Dots and Dashes"

The dark green dots and dashes along banana veins create a "Morse Code" symptom

Morse code appears as short, parallel, dark streaks of different lengths along banana leaf veins
Photographs are courtesy of the University of Hawaii and the Hawaii Department of Agriculture

Maintained by Scot Nelson:
Last Revised on September 12, 2006