Green soybean (edamame), an early-harvested soybean, is a popular vegetable in Asia and is recognised as a healthy vegetable in the other parts of the world. In Japan, edamame yield has gradually decreased over the last 30 years, despite similar cultivation areas. Damage caused by the soybean cyst nematode (SCN), Heterodera glycines, is one of the main causes. We surveyed the distribution of SCN in different locations and found a wide distribution of SCN across Japan. Different control measures are available, such as chemical control using fumigants or a granular type of nematicide, solarisation, and rotation with non-host crops. We are developing a new type of biological control method, which comprises short-term field cultivation and soil incorporation of mung bean. This method not only decreases the SCN density in soil but also mitigates soil erosion and nitrate leaching. For future SCN control it is essential to establish an environmentally friendly management strategy.

Plant-parasitic nematodes (PPN) pose a significant threat to agricultural productivity by causing extensive damage to various crops worldwide. Their complex life cycle and ability to persist in soils make nematode management difficult. Chemical control strategies are emerging as effective but often result in environmental and ecological risks. Biocontrol agents offer a promising alternative with the desired level of reduction in nematode populations without harming non-target organisms. Among the nematode antagonists, Streptomyces spp. is an effective candidate with their ability to produce secondary metabolites that exhibit potent nematicidal properties. Streptomyces avermitilis is the one species that has been completely exploited for nematode and insect management. This review highlights the role of Streptomyces spp. other than S. avermitilis in phytonematode management. Few Streptomyces spp. such as S. yatensis, S. pactum, S. rochei, S. rubrogriseus, S. lincolnensis, S. hygroscopicus, S. antibioticus strain M7, S. albogriseolus ND41 and S. fimicarius D153 are reported to have nematode control potential. Arenimycin, carboxamycin, fervenulin, hygromycin, and lincomycin are some of the Streptomyces-derived compounds that proved to have nematicide potential. Streptomyces spp. also acts as an elicitor of plant defense against nematode intruders. They evinced endophytic potential, plant growth promotion mechanism, compatible nature with other antagonists, and safe to non-target organisms. This current review also highlights the direct and indirect mechanisms by which they control nematodes, another beneficial role in plants, and strategies to upgrade them as commercial products in future thrust areas.

Although plant damages caused by phytoparasitic nematodes has been known at world level since the second half of the 19th century, the most effective methods for their management were discovered only in the past century. At first, plant parasitic nematodes (PPN) were controlled by the same products used against insect pests (carbon disulfide, chloropicrin, methyl bromide), but since 1940, with the discovery of the nematicide activity of the soil fumigant DD (dichlopropane-dichloropropene), chemical nematicides played a pivotal role in increasing the yield of many agricultural crops. In the second half of the past century and especially during its last two decades, the high demand from the farmers for chemical products having immediate nematicidial activity stimulated the interest of many chemical companies in patenting and marketing an increasing number of new chemical products. They were both fumigants (methyl bromide, chloropicrin, dibromoethane, bromochloropropane, dichloroethane, dichloropropane, dichloropropene, dazomet, metam sodium, metam potassium, methyl isothiocyanate, dimethyldisulfide) and non-fumigants (aldicarb, abamectin, benfuracarb, cadusaphos, carbosulfan, carbofuran, benfuracarb, fosthiazate, fluopyram, fenamiphos, ethoprophos, oxamyl, iprodione, thionazin). In the meantime, awareness increased about the negative impact of plant protection products were having on the environment and the need to regulate their approval and use in the European Union (EU). This resulted in a number of EU decrees adopted by all member States to restrict the marketing and use of these products. This led to a drastic reduction in p.a. nematicides on the market, which are already in limited numbers compared to fungicides and insecticides. In this phase of transition towards eco-sustainable agriculture, as alternative products are not yet available for all crops and for all the different species of parasitic nematodes, agricultural operators are having considerable difficulties. The future of the market for synthetic nematicides is not promising. Today, only a handful of active ingredients (dazomet, metam sodium, metam potassiium fenamiphos, fosthiazate, fluopyran, abamectin) are registered in EU. However, studies are underway to search for less polluting products, such as plant extracts, volatile organic compounds, and nano-formulations. The use of these products should be integrated with the implementation of appropriate crop systems, the use of cover crops, soil amendments, rigorous sanitation practices, and resistant planting material, obtained both by conventional and modern technique, for a sustainable control of PPN.