Effect of some plant as soil amendments in the management of Meloidogyne incognita on cucumber (Cucumis sativus L)

Abstract

The root-knot nematode, Meloidogyne incognita constitutes a major constraint to cucumber production. The management of the nematode calls for efforts that are cost-effective, culturally acceptable and environmentally safe. The focus of this study, was to assess the use of dry milled leaves of marigold (Tagetes erecta), Mexican sunflower (Tithonia diversifolia), Siam weed (Chromolaena odorata), and tree basil (Ocimum gratissimum), as soil
amendments in the control of the root-knot nematode M. incognita on cucumber. Greenhouse and field experiments were conducted simultaneously at the National Horticultural Research Institute, Ibadan between 2008 and 2009 to investigate the effects of dry milled leaves of marigold, Mexican sunflower, Siam weed and tree basil each at rates of 1 ton/ha and 2ton/ha; and carbofuran at 1.5 kg a.i./ha and 2.5 kg a.i./ha on M. incognita infecting cucumber. Inoculated and unamended pots and plots served as control. In the greenhouse experiment, carbofuran-treated plants
and Mexican sunflower-treated at 2t/ha produced the highest number of fruits (3 fruits per plant) P=0.05 compared to other treatments while basiltreated and the unamended control produced the least number of fruits (1 fruit/plant). The least galling (1.25) P=0.05 (1.25) and lowest nematode population at harvest (125/250ml soil) were recorded in carbofuran-treated plants and carbofuran-treated soilssoil respectively. No galls were observed on uninoculated control. Under field conditions, carbofuran-treated plotslants and Mexican sunflower at 2t/ha had the highest number of fruits(3.75). No fruit was produced in basil-treated plants and the unamended control. The least root galling (1.00) was also recorded from carbofuran and Mexican sunflower-treated plants while carbofuran treated and Mexican sunflower-treated plotssoils had the least nematode population after harvest (10.25/250ml soil and 14.74/250ml soil, respectively.
The findings suggest that incorporation of marigold, Siam weed or Mexican sunflower at 2t/ha before planting by mixing the dried milled leaves powder with the soil was ieffective for root-knot nematode control in cucumber.