Plant-parasitic nematodes in field crops in South Africa. 6. Soybean

Twelve plant-parasitic nematode genera and 25 species were identified in so il and root samples collected from 17 localities in the soybean production areas of South Africa during the 1995/96 season. Predominant endoparasites found included Meloidogyne incognita. M. javanica. M. hapla, M. ethiopica, Pratylenchus zeae and P brachyurus. Meloidogyne species occurred in 91% of all root samples. P. zeae in 87% and P. brachyurus in 33%. The occurrence o f the three predominant endoparasites was not restricted to sandy soil, but they were also prevalent in soils with high clay contents. Other endoparas itic nematode species were Pratylenchus crenatus, P. teres, P neglectus, P. thornei, Rotylenchulus pan,us and Ditylenchus africanus. Nematodes found i n soil included Helicotylenchus dihystera and Scutellonema brachyarus. whic h occurred in 78 and 71%. respectively. of all soil samples. Other nematode s found in soil samples were Helicotylenchus pseudorobustus, H. digonicus, H. microcephalus, Scutellonema truncatum, Rotlylenchus unisexus, Mesocricon ema sphaerocephalum, Paratrichodorus minor, Longidorus pisi. Xiphinema vand erlindei, X. elongatum and Tylenchorhynchus goffarti. Highest prominence va lues (PV) for Meloidogyne species were recorded on cultivars Prima, Bakgat. Tamboti. Hutcheson and Knap and the lowest on cultivars PAN812, SCSI. Nyal a, Gazelle and A7119. Eight nematode genera and 19 species extracted during this study are reported for the first time in association with soybean in South Africa.