Efficacy of tagetes minuta (African Marigold) in controlling aphids on brassica oleracea

Author

Chibinya, Nomsa J.

Title

Efficacy of tagetes minuta (African Marigold) in controlling aphids on brassica oleracea

Abstract

The main objective of this study was to determine the effectiveness of Tagetes minuta
(Marigold) in controlling aphids on cabbage. A 3x4 factorial experiment in a Randomized
Complete Block Design with three replications was conducted. There were two factors:
Marigold extract concentration (10, 15, 20 g/L) and spraying interval (3, 5, 7 days). Data were
analysed using ANOVA in GenStat. Marigold extract caused dose-dependent mortality of
aphids, indicating strong insecticidal effects (p<0.05). The essential oils and secondary
metabolites (e.g. terpenoids, flavonoids) in Tagetes species likely conferred the insecticidal
properties. The 10 g/L concentration sprayed every 7 days resulted in the highest cabbage
quality and yield (p<0.01). In conclusion, T. minuta extract can effectively control aphids on
cabbage. It significantly reduced aphid populations and was comparable to synthetic
insecticides. T. minuta could be an environmentally-friendly alternative to synthetic
insecticides. However, its effectiveness may depend on the extract concentration, application
frequency and timing, and aphid infestation level. Further research is needed to optimize T.
minuta as an aphid control method. Based on these findings, farmers and gardeners are
recommended to consider using T. minuta to control cabbage aphids. Further research should
optimize T. minuta use by determining the ideal extract concentration and application regime,
and evaluating environmental impacts. Educating farmers and policymakers about natural
control methods like T. minuta could promote sustainable agriculture and reduce reliance on
synthetic insecticides. Policy supporting R&D into natural insecticides is also recommended.

Date

2023

Publisher

BUSE

Keywords

Cabbage production

Pest control

Aphids

Brassica oleracea

Tagetes minuta

African marigold

Supervisor

Dr Chikuvire, T. J

Chikasha, T.E