SURVEY AND IDENTIFICATION OF PLANT PARASITIC NEMATODES ASSOCIATED WITH SWEET POTATO AND CASSAVA

Abstract

A survey of plant parasitic nematodes associated with sweet potato and cassava was conducted during the dry and rainy seasons of 1977 in 30 municipalities in two provinces of Leyte, Philippines. A total of 430 and 275 soil samples were gathered from sweet potato and cassava fields, respectively. Thirteen genera and 22 species of nematodes were identified to be associated with sweet potato: 12 genera and 17 species were associated with cassava. Rotylenchulus, Meloidogyne and Helicotylenchus were the most prevalent and widely distributed genera. Species of Meloidogyne were identified mainly by the perineal patterns of egg-laying females. Other nematodes were identified by their size, position of the vulva, number of lip annules, and head and tail region of adult females. In both sweet potato and cassava, the population density and distribution of the different nematode genera varied considerably from one locality to another. The differences may be attributed to such factors as soil type, soil moisture and cropping pattern in the area.