Case study of effect of glyphosate application on plant-parasitic nematodes associated with a soybean–maize rotation system in South Africa

Abstract

Information on the effect of the herbicide glyphosate on nematodes in the field is limited and contradictory. A small field experiment was conducted during two consecutive summer-growing seasons to investigate the response of plant-parasitic nematode communities on the application of glyphosate to genetically-modified glyphosate-tolerant soybean (cultivar ‘LS 6164 R’) and maize (cultivar ‘DKC 80-30 RR’). A mixed Meloidogyne incognita and Meloidogyne javanica population dominated both crops during both seasons. Five other plant-parasitic nematode genera (Criconema, Helicotylenchus, Nanidorus, Pratylenchus and Tylenchorhynchus) were also identified. Glyphosate application had no effect on M. incognita, M. javanica and Pratylenchus spp. numbers. No significant differences were observed between the glyphosate-treated and non-treated plots for Meloidogyne population densities per 50 g roots for both soybean and maize. Significant (p ≤ 0.05) differences recorded between glyphosate-treated and non-treated plots from 5 g roots and 200 g rhizosphere soil for other genera were mainly due to absence during some sampling dates.