Efficacy of Plant Materials in Controlling Aphids on Okra (Abelmoschus esculentus L. Moench) in Limpopo Province of South Africa

Abstract

Smallholder farmers in Limpopo Province generate income through growing vegetable crops such as cabbage, tomato, and okra. These crops are produced for local and national markets. Okra crops are highly constrained by aphids. Smallholder farmers rely only on synthetic insecticides to manage aphids. This paper evaluated the efficacy of five plant materials (bio pesticides): pawpaw (Carica papaya L.), Mexican marigold (Tagetes minuta L.), serrano pepper (Capsicum annuum L.), common lantana (Lantana camara L.) and tobacco (Nicotiana tabacum L.) on Aphis gossypii population in okra production. The field experiment was laid in a randomized complete block design, with seven treatments (five plant materials, mercaptothion insecticide as a control and the absolute control) replicated three times. Aphid abundance, leaf damage and the correlation between leaf damage and aphid abundance were analyzed using analysis of variance. Carica papaya L. (0.87) and Tagetes minuta L. (0.87) were more effective in reducing aphid abundance. Leaf damage caused by aphids was lowest in the Carica papaya L. treatment (1.11) and the Tagetes minuta L. treatment (1.12). There was a strong positive correlation between aphid abundance and leaf damage (r = 0.86). Plant materials: Carica papaya L. and Tagetesminuta L. could be incorporated into an overall integrated pest management system to reduce aphid abundance and leaf damage.