The last few years have witnessed the emergence of alternative measures to control plant parasitic nematodes (PPNs). We briefly reviewed the potential of compost and the direct or indirect roles of soil-dwelling organisms against PPNs. We compiled and assessed the most intensively researched factors of suppressivity. Municipal green waste (MGW) was identified and profiled. We found that compost, with or without beneficial microorganisms as biocontrol agents (BCAs) against PPNs, were shown to have mechanisms for the control of plant parasitic nematodes. Compost supports a diverse microbiome, introduces and enhances populations of antagonistic microorganisms, releases nematicidal compounds, increases the tolerance and resistance of plants, and encourages the establishment of a “soil environment” that is unsuitable for PPNs. Our compilation of recent papers reveals that while the scope of research on compost and BCAs is extensive, the role of MGW-based compost (MGWC) in the control of PPNs has been given less attention. We conclude that the most environmentally friendly and long-term, sustainable form of PPN control is to encourage and enhance the soil microbiome. MGW is a valuable resource material produced in significant amounts worldwide. More studies are suggested on the use of MGWC, because it has a considerable potential to create and maintain soil suppressivity against PPNs. To expand knowledge, future research directions shall include trials investigating MGWC, inoculated with BCAs.

The distribution of species of the Xiphinema americanumgroup in Hungary was studied by collecting 272 samples from 53 localities. Samples have been taken from soil in the rhizosphere of 70 plant species. In total, 12.86 % of the samples contained at least one species from the Xiphinema americanum-group. Three species were found: Xiphinema brevicollum, X. pachtaicum and X. simile. Xiphinema brevicollum occurred in 4.41 %, X. pachtaicum in 3.67 % and X. simile in 4.77 % of the samples. New data on plants associated with the reported species and developmental patterns for X. brevicollum and X. pachtaicum are also presented.

The application of Trichoderma spp. for the suppression of plant-parasitic nematode populations is a promising tool in biological control. Sixteen strains of six Trichoderma species (T. atroviride, T. harzianum, T. rossicum, T. tomentosum, T. virens and T. asperellum) were tested in vitro in order to identify the most appropriate strains to control the dagger nematode Xiphinema index. Mortality assays revealed that the strains of the widely investigated T. harzianum species have caused significant reduction of X. index populations, although T. harzianum strains were not the most efficient among all the tested fungi. Certain T. virens and T. atroviride strains and T. rossicum have triggered faster and higher mortality. Generally, our data indicate that Trichoderma species have innate ability to decrease X. index population. Furthermore, as we had difficulties with maintaining X. index in vitro, we successfully used a newly developed method to keep X. index specimens viable during the experiments.

Lethal effects of neem derived pesticides (neem leaf extract (NLE) and NeemAzal-T/S (NA)) were examined on different entomopathogenic (EPN) and slug-parasitic (SPN) nematodes. In our recent study, neem derived pesticides were tested against Phasmarhabditis hermaphrodita for the first time under in vitro conditions. Laboratory experiments were set up in 96-well microplates with different concentrations of NLE (0.1%, 0.3%, 0.6%, and 1%) and NA (0.001%, 0.003%, 0.006%, and 0.01%) and Milli-Q water as the control. After 24-h exposure time, mortality of individual nematodes was observed and recorded. Considering LC₁₀ values, 0.1% of NLE could be used safely in combination with all the EPNs and SPNs tested in recent study. A concentration of NA three times higher than the recommended dosage did not harm either EPN or SPN species. In conclusion, NeemAzal-T/S might be applied with EPNs and the SPN Ph. hermaphrodita simultaneously, while the compatibility of neem leaf extract and beneficial nematode products needs further evaluation.

Summary: A 25-year-old intensive monoculture of cucumber ( Cucumis sativus ‘Monolit F1’) has been chosen for monitoring the effect of continuous fertilization, drip irrigation and various soil disinfection on free-living nematodes in soil. Densities, relative abundance of nematode genera, trophic groups and c-p classes, in addition, numerous nematological indices were determined besides certain soil properties. Concerning the nematological indices, all the values proved a stressed, depleted and unstable environment with degraded food web condition. The exaggerated application of fertilizers through irrigation caused high salinity values (0.62 %) which is much higher than the indicated toxicity threshold (0.4 %) for cultivated plants. The number of individuals of the bacterivore Acrobeloides and Cuticularia genera, which have a very high stress tolerance, was outstanding in the area. Besides juveniles, the appearance of Meloidogyne incognita males was also recorded which could lead to a change in the genetic composition of the population to adapt to environmental stressors. All these changes may result from salt stress indicated by intensive drip irrigation and the use of artificial fertilizers.

Although the incorporation of organic amendments into the soil is widely researched, less attention has been given to the impact of in-situ composting of municipal green wastes (MGW), especially leaf litter, on free-living nematodes. In a four year experiment (2016–2019) of tomato cropping cycles, we tested the hypothesis that leaf litter mulch has a positive effect on mononchid predatory nematodes and influences their species composition. Two treatments were applied every year: plots were either mulched with leaf litter or left unmulched. Soil samples were collected every autumn at the end of the growing season. Active, free-living nematodes were extracted by Baermann funnel from soil samples, the density of mononchid predatory nematodes was determined, and the individuals were identified to genus or species. In the first year (2016), mulching did not affect the density of mononchids. From the second year (2017) on, their number significantly increased in mulched plots, compared to in unmulched ones. During the study period the presence of four mononchid genera: Clarkus, Mylonchulus, Prionchulus, and Iotonchus, were detected. Our hypothesis was confirmed, as the number of mononchids increased in the presence of MGW leaf litter mulch layer.