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

Abstract

Twelve plant-parasitic nematode genera and 25 species were identified in soil 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 of the three predominant endoparasites was not restricted to sandy soil, but they were also prevalent in soils with high clay contents. Other endoparasitic nematode species were Pratylenchus crenatus, P. teres, P. neglectus, P. thornei, Rotylenchulus parvus and Ditylenchus africanus. Nematodes found in soil included Helicotylenchus dihystera and Scutellonema brachyurus, which occurred in 78 and 71%, respectively, of all soil samples. Other nematodes found in soil samples were Helicotylenchus pseudorobustus, H. digonicus, H. microcephalus, Scutellonema truncatum, Rotylenchus unisexus, Mesocriconema sphaerocephalum, Paratrichodorus minor, Longidorus pisi, Xiphinema vanderlindei, X. elongatum and Tylenchorhynchus goffarti. Highest prominence values (PV) for Meloidogyne species were recorded on cultivars Prima, Bakgat, Tamboti, Hutcheson and Knap and the lowest on cultivars PAN812, SCS1, Nyala, 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.

Nematode pests threatening soybean production in South Africa, with reference to Meloidogyne

“…That root-knot nematodes are generally the predominant plant-parasitic nematodes associated with local soybean crops 8,20 corresponds with reports that these pests are also considered as a serious constraint to production of the crop worldwide 22,23 . Diagnostic nematode analyses revealed exceptional high root-knot nematode population density levels of 11 401 eggs and J2/50 g roots from RR plants that grew in the Bothaville area (Free State Province) during the 2011 season.…”

“…9,19 The first extensive nematode survey was conducted during 1995/1996 at 17 localities situated within the local soybean production areas. 20 …”

Virulence of Entomopathogenic Nematodes against Meloidogyne incognita for Invasion, Development and Reproduction at Different Application Times in Brinjal Roots

“…In Punjab (Pakistan), it was cultivated on an area of 4.7(000) ha with an annual production of 59.2 (000) tons during [2009][2010], with the average yield of 12.6 tons/ ha, which is very low as compared to other Asian countries (Anonymous, 2011). Root-knot nematode [Meloidogyne incognita (Kofoid and White) Chitwood] is widespread and destructive pathogen of brinjal (Fourie and McDonald, 2000). RKNs attack more than 3000 species of plants, including almost all cultivated plants and reduce world crop production by about 5% losses in individual fields, however may be much higher (Agrios, 2005).…”

Host suitability of selected South African maize genotypes to the root-knot nematode speciesMeloidogyne incognitarace 2 andMeloidogyne javanica: A preliminary study

“…The numbers of eggs and J2 of both nematode species got alarmingly high in roots of some hybrids at 56 DAI, even when compared to other traditionally more susceptible crops (Fourie et al, 1999;Fourie et al, 2001). When these hybrids are grown, whether in monocropping or in rotation systems with other root-knot-nematode-susceptible crops, the nematode damage may be cumulative in successive growing seasons.…”

“…Resistance percentage (number of eggs and J2 per root system of each genotype evaluated ÷ number of eggs and J2 per root system obtained for the most susceptible genotype x 100) and reproduction factors [Rf = final egg and J2 numbers (Pf) ÷ inoculated egg and J2 number (Pi)] were used as the criteria to screen for nematode resistance in maize genotypes. These parameters proved to be discriminant tools for identification of root-knot-nematode-resistant sources in different of crops (Windham & Williams, 1988;Fourie et al, 2001;Hussey & Janssen, 2002;Fourie et al, 2005;Cook & Starr, 2006). Nematode data were subjected to an analysis of variance (Statgraphics Plus 5 for Windows).…”