RESISTANCE OF FIFTY-TWO SWEET POTATO [Ipomoea batatas (L.) LAM.] CULTIVARS TO Meloidogyne incognita AND M. javanica

Abstract

Of the 52 sweet potato cultivars screened, 13, 4, 7 and 28 were susceptible, moderately susceptible, moderately resistant and resistant, respectively, to Meloidogyne incognita. With M. javanica, only one cultivar was found susceptible, one was moderately susceptible, three were moderately resistant and 47 were resistant.
Based on egg mass rating index, the most resistant cultivar to M. incognita was W-86 followed by L4-89, BPA-4 and Sinibastian whereas Gold Rush, Binicol, C1596-9, Catanduanes and BNAS-51 were most susceptible. UPR was the only cultivar found susceptible to M. javanica.
Highly significant positive linear correlation was observed between resistance rating and the parameters used, viz., number of egg masses and root galls, nematode population in roots, egg mass and gall indices. Egg mass index was the main criterion used in assessing resistance since galling index was inadequate because galls produced in sweet potato were small and indistinct.