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

Abstract

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).

Onion (Allium cepa) and garlic (Allium sativum) as pest control intercrops in cabbage based intercrop systems in Zimbabwe

“…This conforms to the research by [6] who indicated that canopy spread did not differ significantly. In another study with cabbagetomato intercrop, there was no significant difference in the size of the cabbage heads at maturity between the intercrop and the monocrops [5].…”

“…4.1Pest prevalence on cabbage plants at physiological maturity Pest prevalence was lower in intercropping treatments due to fewer Bemisia tabaci, Hellula undalis and Brevicoryne brassicae [6] that infested the intercropped plants than the sole crop. Garlic and onion are potentially effective in controlling pests on cabbages.…”

“…The sole cabbage plants that were infested early could not completely survive the attack and as a consequence produced lighter heads [6] and hence low mass. Similarly, foliar damage and yield loss was more in monocropped than intercropped plots [14].…”

“…Plant pests cause considerable damages and losses in vegetable production. Some of the pests suck cell sap from plants which reduces plant potential to photosynthesise, destroy growing buds as well as tunnelling into whole cabbage heads [6]. This reduces plant productivity and decline in market value of the produce as a result of tear and shattering [7] and subsequent loss to the farmer [6], in some cases total crop failure [5].…”

“…Despite the efficiency, and ease of utilisation, synthetic pesticides result in environmental contamination and water pollution (when toxic substances introduced into water bodies in quantities which affect the resource in providing valuable services of domestic use, navigation, irrigation, recreational and life (ecological) functions [6]. The European Union (E U) has put in place some restrictive compliance standards, one of which pertains to chemical residues in food produce [8].…”