Effect of Nitrogen, Phosphorus and Potassium Fertilization on the Management of Brevicoryne brassicae in Rapeseed Fields

The cabbage aphid, Brevicoryne brassicae (L.) is the most important pest of canola (Brassica napus L.) in Iran. Two same field trials (control and infested) were conducted to study the effect of macroelements (NPK) fertilizer on cabbage aphid population on rapeseed SLM046 at Borujerd agricultural research station during 2002-2003. The RCBD with factorial arrangement was used with three factors, N (N1=0, N2=190, N3=270, N4=350 Kg/ha), P (P1=0, P2=150 Kg/ha) and K (K1=0, K2=100 Kg/ha). Result showed that, at the beginning of stem stage (in late March), when the urea was applicated at the second time, aphid infestation at fertilizer level N4 significantly decreased. But after the blooming stage (in late April), when the urea was applicated at the third time, aphid infestation in N4 was increased. According to this research, Nitrogen (N) alone and its interaction with Phosphorus (P) and Potassium (K), significantly decreased the damage of B. brassicae in the canola fields.