Insecticide Use Patterns and Residue Levels on Cabbage, Brassica Olerecea Var. Capitata L., Cultivated Within the Accra-Tema Metropolitan Area of Ghana

Abstract

Concerns have been expressed by pesticide management specialists about the choice and use of insecticides in cabbage production and fear of toxic residues on harvested cabbage head. This investigation involves a survey to determine cabbage fanners’ insecticide use patterns and analysis for insecticide residues on samples of cabbage. The survey revealed that cabbage growers in the Accra-Tema Metropolitan area of Ghana invariably relied on insecticide retailers/agents for advice on the choice and use of insecticides for insect pest control purposes. The insecticides of choice were, Bacillus thuringiensis subsp. Kurstaki Berliner, Lambdacyhalothrin, Chlorpyrifos, Dimethoate, Deltametrin, Triazophos, Cypermethrin, Profenofos and Pirimiphos-methyl. These insecticides were used either in alternation or as mixtures. Additionally, the insecticides were sprayed frequently and at short intervals on cabbage without the consideration of threshold levels. Residues of Karate 2.5 EC (Lambdacyhalothrin) and Deltaphos 262 EC (250g/l Triazophos + 12g/l Deltamethrin) were determined on samples of cabbage, by estimation of biotoxicity to the brine shrimp nauplii. Residues of Lambdacyhalothrin were lower than the FAO/WHO recommended maximum residue level (MRL). The residues of Deltaphos 262 EC detected, however, suggested that the residue levels of Triazophos were likely to be higher than FAO/WHO recommended MRL