In order to overcome the difficulties of applying pesticides in flooded rice, the authors designed and built a light-weight spray boom for use with a local type of boat. The 5 m long boom is equipped with four Micron rotary atomisers powered by a 12 volt car battery and can spray a 4 m swath on one side of the boat. The major pest in Bangladesh ricefields is the stem borer,Tryporyza incertulas. Field trials using this equipment to spray diazinon showed a reduction in stem borer infestation and an increase in yield.