Life cycle duration of Meloidogyne incognita and host status of Brassicaceae and Capparaceae selected for glucosinate content

Different plant species in the families Brassicaceae and Capparaceae were evaluated for their potential use in management of the root-knot nematode, Meloidogyne incognita. Preliminary tests on host suitability were carried out for toxic effects on the nematode in small field plots of soil naturally infested with M. incognita. Afterwards, the best accessions and a susceptible tomato cultivar (UC82) were tested in pots to collect more complete observations of the nematode life cycle on the selected plant roots. Plants were cultivated in the glasshouse for 14-15 weeks and evaluated every 2 weeks. Root gall rating, population reproduction factor and life cycle duration showed wide differences amongst the different accessions and indicated two distinct approaches for control of M. incognita: catch crops or green manure. At 14-15 weeks after sowing, Rapistrum rugosum sel. ISCI 15, Eruca sativa cv. Nemat, Barbarea verna sel. ISCI 50 and Raphanus sativus cv. Boss were considered 'poor to nonhost' species; Brassica juncea sel. ISCI 99 was classified as 'maintenance host'; Lepidium campestre sel. ISCI 103 and Erucastrum gallicum were 'good hosts'. At 10 weeks after sowing, B. juncea sel. ISCI 20 was classified as a good host, so it could be grown for fewer than 8-10 weeks in a cropping system. The presence of galls and the identification of juveniles, females and egg masses, confirmed that second-stage juveniles had penetrated into the root of the tested accessions and completed their life cycle. However, in R. rugosum sel. ISCI 15, M. incognita did not complete its life cycle, even after 15 weeks.