Ageratum conyzoides L. for the management of pests and diseases by small holder farmers

Ageratum conyzoides L. (Asteraceae) is an aromatic, annual herb and cosmopolitan weed commonly known as billygoat weed or goat weed and is typically found in cultivated fields and other disturbed ecosystems. The species has been studied widely owing to its biological properties and its potential application in medicine and agriculture. Due to its importance and use in the treatment of burns and wounds, arthrosis, malaria, asthma, leprosy and dermatitis, its medicinal properties have been reviewed. A. conyzoides, however, also has insecticidal activity against a range of major pests of field crops and stored products including Callosobruchus chinensis L. (Coleoptera: Chrysomelidae), Chilo partellus Swinhoe (Lepidoptera: Crambidae), Sitophilus oryzae L. (Coleoptera: Curculionidae), Panonychus citri McGregor (Tetranychidae: Panonychus), Sitophilus zeamais Motchulsky (Coleoptera: Curculionidae), Plutella xylostella L. (Lepidoptera: Plutellidae) and Brevicoryne brassicae L. (Hemiptera: Aphididae). Evidence suggests that its efficacy is comparable to synthetic pesticides and that it is economically viable too while its impact on beneficial insects including ladybirds, hoverflies and spiders is much reduced compared to synthetics. Anti-microbial activity against important agricultural disease agents is also reviewed here including against Fusarium oxysporum Schltdl., (Hypochreales: Nectriaceae), Phytophthora citrophthora (R.E. Sm. & E.H. Sm.) Leonian, (Phythiales: Phythiaceae), Pythium aphanidermatum (Edson) Fitzp., (Peronosporales: Pythium), Fusarium solani Mart (Sacc.) (Hypochreales: Nectriaceae) and Gibberella zeae (Schwein.) Petch (Fusarium graminearum (Schwabe) (Hypochreales: Nectriaceae). These activities suggest a compelling multipurpose plant that has merit as a potential commercial species. Since earlier reviews have focused on medicinal properties of A. conyzoides and less on its potential value in agriculture, this review seeks to bridge this gap by reviewing research on the various properties of this species that are relevant to food production. The review presents updated information on the use of this species as an agricultural resource and emphasizes its potential as an industrial crop.