Bionematicides: from sidekick to lead role. Experiences with seaweed-based products

Bionematicides: from side kick to lead role. Experiences with seaweed-based products.

Wim M.L. Wesemael1,2, Bruno M. Ngala2,3, Yirina Valdés Vazquez2, Nicole Viaene1,2 and Roland N. Perry2,4
1 Institute for Agricultural and Fisheries Research (ILVO), Burg. Van Gansberghelaan 96, B-9820 Merelbeke, Belgium
2 Faculty of Science, Ghent University, Ledeganckstraat 35, B-9000 Ghent, Belgium
3 Crop and Environment Science Department, Harper Adams University, Newport, Shropshire, TF10 8NB, UK
4 School of Life and Medical Sciences, University of Hertfordshire, Hatfield, Herts AL10 9AB, UK

Due to decreasing availability of classical nematicides new products are needed and, thus, there is increasing interest in bionematicides. Scientific research focused on biocontrol agents Pasteuria spp., Pochonia chlamydosporium and Purpureocillium lilacinus, all available as commercial products targeting plant-parasitic nematodes. Many plants contain or release compounds with nematicidal activity. Knowledge on their mode of action, stability and practical application is limited. Several products containing bacteria and fungi are commercialised as plant-growth promoters and soil conditioners. Effects on plant-parasitic nematodes have been reported after their application. Seaweed-based products also have an effect on different plant-parasitic nematodes. Seaweed extracts from Ascophyllum nodosum used as a soil drench in a pot test improved the growth of Meloidogyne chitwoodi and M. hapla infected tomato plants and reduced hatch and infectivity of second-stage juveniles (J2) in vitro. However, the level of control achieved with these applications alone may be insufficient under normal agricultural conditions. Extracts from Ecklonia maxima gave an increased movement of J2 towards host plant roots but hampered movement in the presence of a repellent (acetic acid). Further studies on how biological compounds affect the behaviour and life cycle development of plant-parasitic nematodes are needed to facilitate the development of successful bionematicides. As market uptake increases, the need for independent efficacy data is high. Rather than a secondary effect on plant growth, the nematicidal potential of natural products should be a main topic for scientists and companies.