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

Abstract

Cultural methods can be implemented to reduce the problems that have been caused by indiscriminate use of insecticides. An experiment was carried out in Makonde District, Zimbabwe to determine the ability of onion and garlic to reduce pest problem when intercropped with cabbages. A randomised complete block design was used with five treatments replicated three times. The treatments were (1) cabbage intercropped with garlic within rows, (2) cabbage intercropped with onion within rows (3) Cabbage and onion intercropped within rows (4) Cabbage and garlic intercropped within rows and (5) Sole cabbage. Data collected were on pest prevalence at physiological maturity, cabbage plants that survived at three weeks after planting (WAP), number of cabbage leaves damaged by insect pests at 6 (WAP), cabbage head diameter and yield of cabbages at physiological maturity. Intercropping cabbage significantly reduced pest prevalence, plant death after transplanting, leaf damage and increased cabbage yield compared to sole cabbage crop. However there were generally more benefits when intercropping with either garlic or onions between the rows than within the rows though not statistically different from intercropping within the cabbage rows at p<0.05.