Solving big problems requires accurate information. Rice in the area of Cambodia near Vietnam was extensively damaged by the brown planthopper (BPH) from 2007 to 2009, with all districts in Takeo province in the area of Cambodia near Vietnam severely affected. How did farmers learn of methods to protect rice plants? This study seeks to reveal how methods to control the BPH were diffused in Cambodia through interviews with farmers, local governmental officials, and village chiefs in the target province. The farmers stated that they controlled the BPH with nets and beating as physical controls and spraying mixed oil & ash and chemical pesticides as chemical controls. They tended to source their own information and experiences of neighbors, government officials, and pesticide sellers, while farmers in three communes very severely affected by the BPH infestation followed the advice of sellers in employing pesticides. Further, most local government officials and village chiefs recommended using nets and spraying oil mixtures and chemical pesticides. The flow of information from the resource to individual farmers seemed to be linked to the level of BPH infestation.