In southern India, brown planthopper (BPH) Nilaparvata lugens takes a heavy toll on rice production. It directly causes damage and acts as a vector of many diseases. An experiment involving a cultural method of control was conducted using synthetic fertilizers and biofertilizers. Biofertilizers are becoming popular as a cheap and safe alternative to conventional chemical fertilizers (Sharma 2001).
The experiment was laid out in a completely randomized block design in the insectary. Test variety ADT36 was planted in pots with wetland soil collected from the field. There were nine treatments (1: 100-50-50 kg NPK ha-1, 2: 120-50-50 kg NPK ha-1, 3: 2 kg azospirillum ha-1, 4: 500 kg azolla ha-1, 5: 100-50-50 kg NPK ha-1 + 2 kg azospirillum ha-1, 6: 100-50-50 kg NPK ha-1 + 500 kg azolla ha-1, 7: 120-50-50 kg NPK ha-1 + 2 kg azospirillum ha-1, 8: 120-50-50 kg NPK ha-1 + 500 kg azolla ha-1, 9: untreated check [12.5 t farmyard manure ha-1]) and each treatment was replicated thrice. Five hills were maintained per plot. Inorganic and organic fertilizers at the computed doses were applied in the respective treatments and the soil was thoroughly mixed.