Fauzana, HafizWagiman, F.XMartono, Edhi2019-01-082019-01-082019-01-09978-979-792-865-0wahyu sari yenihttp://repository.unri.ac.id/handle/123456789/9512Brown planthopper (BPH), Nilaparvata lugens (Hemiptera: Delphacidae), is the main pest of rice that threatened Indonesia food security. The coal fly ash contribute to control the BPH. The coal fly ash contribute to control the BPH. The coal fly ash activity needs to be studied under semi-field and field conditions. The purpose of the study was to assess activity of coal fly ash to BPH tested in laboratorium, semi-field and field conditions. The coal fly ash obtained from PT. PLN (Govermental Electricity Corporation Ltd.) Tanjung Jati B Power Station in Jepara District, Central Java. Pot experiments were using the difference doses of coal fly ash as a treatment that was 0, 20, 40, and 80 g / clump. The experiment was arranged based on complete randomized block design (RCBD) with five replications. Field experiments were testing the effect of coal fly ash on the population of BPH were done by comparing the treatment and control of coal fly ash. The coal fly ash activity in the semi-laboratory conditions of 32 g coal fly ash / largest bowl caused the nymph mortality and BPH imago.The semi field experiment showed an effective dose of 80 g/hill which was equal to 20 tons/ha. Field trial compared the effect of coal fly ash dosage of 20 tons/ha to control the brown planthopper population. The findings showed that the activity of coal fly ash significantly reduced the BPH population until day 7 (H +7).enBrown planthopperNilaparvata lugenscoal fly ashactivityriceArticle