AbstrakPengembangan usaha tani kentang di Kabupaten Karo dan Kabupaten Simalungun Sumatera Utara sangat dibatasi oleh tingginya serangan hama sehingga penggunaan pestisida mutlak dibutuhkan. Peningkatan dosis Kalium dan penggunaan pestisida nabati merupakan suatu strategi untuk mengurangi serangan hama pada kentang. Penelitian ini bertujuan untuk mengetahui apakah peningkatan dosis Kalium dan aplikasi beberapa pestisida nabati dapat menurunkan persentase serangan hama pada tanaman dan meningkatkan produksi kentang. Penelitian dirancang dengan Rancangan Acak Kelompok (RAK) factorial dengan 2 faktor yaitu Dosis Kalium yang terdiri dari 4 taraf : K0 = Kontrol ; K1= 100 kg/ha (30 g/plot) ; K2= 150 kg/ha (45 g/plot) ; K3 = 200 kg/ha (60 g/plot). Dan Faktor kedua adalah jenis pestisida nabati yang terdiri dari 3 taraf yaitu : N 1 =20 g/liter air Ekstrak Daun Mimba ; N 2 = 20 g/liter air Ekstrak Daun Babadotan ; N 3 =20 g/liter air Ekstrak Daun Kipahit. Data dianalisis dengan sidik ragam. Hasil penelitian menunjukkan bahwa peningkatan dosis Kalium tidak berpengaruh nyata terhadap persentase serangan hama dan peubah produksi tanaman. Jenis pestisida nabati berpengaruh nyata terhadap persentase serangan hama, akan tetapi tidak berpengaruh nyata terhadap peubah produksi tanaman. Persentase serangan hama paling rendah diperoleh pada aplikasi pestisida nabati ekstrak daun babadotan. Secara umum persentase serangan hama termasuh kategori sangat ringan (<25%). Kata kunci : pestisida nabati, hama, kentang. AbstractPotato production in Karo and Simalungun Regency of North Sumatra is severely limited by the high number of pest attacks, so that the use of pesticides is absolutely necessary. Increasing potassium doses and application botanical pesticides can be used as a strategy to reduce pest attacks on potatoes. This study aims to determine whether an increase in potassium dose and application of some botanical pesticides can reduce the percentage of pest attacks and then increasing potato production. Research was designed by factorial Randomized Block Design (RBD) with 2 factors, namely Potassium Dosage consist of 4 levels: K0 = Control; K1 = 100 kg / ha (30 g / plot); K2 = 150 kg / ha (45 g / plot); K3 = 200 kg / ha (60 g / plot). And the second factor is the type of botanical pesticide which consist of 3 levels, namely: N1 = 20 g Neem leaves/ liter of water; N2 = 20 g babadotan leaves/ liter of water; N3 = 20 g Kipahit leaves/ liter of water. Data were analyzed by analyzed of variance. The results showed that an increase in potassium dosage did not significantly affect the percentage of pest attacks and plant production variables. Botanical pesticides have a significant effect on the percentage of pest attacks, but have not significant effect on crop production variables. The lowest percentage of pest attacks was obtained from the application of botanical pesticides from babadotan leaf extract. In general, the percentage of pest attacks in the category was very low (<25%), so that not significantly affect to production variab...