Response of sweet potato selections to the southern root-knot nematode Meloidogyne incognita in Venezuela.

Twenty-eight Ipomoea batatas selections in the Root and Tuber Germplasm Collection of the Agronomy Department of Central University of Venezuela, Maracay, Venezuela, were evaluated for reaction to the southern root-knot nematode, Meloidogyne incognita race 2 Initial densities (Pi) of a combination of 6 eggs and second-stage juveniles per one cm(3) of soil were used in a greenhouse replicated study. All selections, except 'UCV-8', were susceptible to M. incognita infection. The nematode reproduction rate (Pf/Pi) on 'UCV-8' was < 1 and the galling index value, on a scale 0-5, was 2.5. Low reproduction rates and gall index values of 2.9, 2.4, 2.4, and 2.3 were observed on die selections 'UCV-21', 'UCV-22','North Carolina' and 'E-690' respectively.