ABSTRACT Experiment about the effect of infestation time and competition time of purple nutsedge (Cyperus rotundus L.) on the growth and yield of shallot (Allium ascalonicum L.) with the supervision by Djoko Purnomo, Wartoyo, Historia- wati. This experiment was conducted August 12, 1992 until October of 12 at Tuguran, Magelang on latosol soil type in altitude of 367 meters a…