Cold aqueous extracts of African marigold, Tagetes erecta for control tomato root knot nematode, Meloidogyne incognita

Cold aqueous extracts (20% w/v, 100 ml aliquots) of pre- and post-flowering whole plants, root and stem portions of Tagetes erecta were tested for their ability to control M. incognita in infested soil (10 kg) in pots planted with susceptible Lycopersicon esculentum. Plant height and leaf number were significantly greater in T. erecta treated L. esculentum than plants grown in untreated infested soils. Whole T. erecta plant extracts were more efficacious than stem extracts although both were more effective than root extracts and extracts from 40-day old plants were more efficacious than those from 70-day old plants. Root gall indices of L. esculentum treated with T. erecta plant extracts were significantly lower than untreated checks and comparable with carbofuran-treated plants. Similarly, fruit yield from plants treated with T. erecta extracts was significantly better than untreated checks and comparable with carbofuran-treated plants. The value of applying T. erecta extracts as an alternative to intercropping for farmers is discussed.