Onion as a Pest Control Intercrop in Organic Cabbage (Brassica oleracea) Production System in Ghana

The use of chemical insecticides in the control of insect pests has left in its wake resistance of some pests to some of the conventional insecticides. Alternative methods of managing pests such as cultural control have to be employed to reduce pest infestation of crops. Onion was used in an intercrop as a non host crop to manage the pests of cabbage. The experiment was conducted in a Randomized Complete Block Design with four treatments; sole cabbage (T1), 2 rows of cabbage to 1 row of onion (T2), 3 rows of cabbage to 1 row of onion (T3) and 4 rows of cabbage to 1 row of onion (T4), each of which was replicated three times. Data were collected on pests’ numbers, plant height, damaged leaves at harvest, canopy spread, number of damaged heads and fresh weight. Significantly fewer Bemisia tabaci, Hellula undalis and Brevicoryne brassicae infested the intercropped plants than the sole crop. However, intercropping cabbage with onion did not significantly reduce Plutella xylostella population on cabbage. Number of damaged heads, fresh weight and damaged leaves were significantly different (P< 0.05).