Plant pathogenic nematodes play an important role in crop production and are difficult to control. One of them is Heterodera schachtii—a cyst nematode, pathogenic to sugar beet. Nature suggests a natural way to resolve this problem by using nematode-trapping fungi, one of which is Pleurotus ostreatus. It is one of the most widespread mushrooms in the world. It is a valuable and widely cultivated edible mushroom with nematocidal properties. The mycelium of this mushroom produces toxin droplets that paralyze nematodes, after which the nematodes become infected with the hyphae filament, resulting in their death. This feature can be put to practical use as a natural nematocidal agent. In this paper, we have described studies on the variability of the nematocidal properties in the progeny of three wild strains of P. ostreatus (Po1, Po2, Po4), obtained by crossing dikaryons with monokaryons (Buller phenomenon). The toxicity of mycelium was tested against the model organism Caenorhabditis elegans and against sugar beet pest—H. schachtii. The results of the study allowed the selection of the progeny heterokaryotic mycelia with the best parameters useful for in vitro control of both nematodes. They differed in the activity against C. elegans and H. schachtii, and in the toxic knobs production. The results indicated that the progeny of the Po1 strain presented a good ability to produce hyphal knobs in the presence of C. elegans, and progenies of the Po4 strain presented good quality of growth in preferred temperatures (10–25 °C). Three strains Po1 5dix27, Po2 20dix21, and Po4 2dix1, as well as a maternal strain Po4 controlled H. schachtii by entwining cysts better than other strains. These strains were moderately effective against C. elegans. Strains Po2 15dix17, Po4 1dix18, and Po4 1dix30 may be considered good controlling isolates against both tested organisms. The results of the research also clearly suggest that the killing properties of P. ostreatus mycelia should not be assessed only by their ability to produce toxic hyphal knobs. Their nematocidal properties also depend on other mechanisms developed by mycelia, which is observed as the lethality of nematodes. The results of this research will lead to a natural way to protect plants against nematodes. The research also proved the nematocidal properties of the wild strains to reduce the H. schachtii population in the soil.

In the period of 2016–2018, two series of field studies on organic sugar beet growing (Beta vulgaris L.) were carried out in northern Poland on Luvisol loamy soil (medium–heavy) soil in Bałcyny and Płonne. The aim of this study was to decrease the yield gap between organic and conventional beets. Factors to increase the yield of organic beet were differentiated fertilization (cattle farmyard manure (FYM), compost, and Bioilsa) and choice of varieties (Eliska, Jampol, and Sobieski). The reference point was the conventional cultivation of the same sugar beet varieties, fertilized with manure and NPK mineral fertilizers, the prevailing standard of sugar beet cultivation in Poland. High sugar beet root yields exceeding the average yield in Poland by 25–30% were obtained in both studies, both in conventional and organic cultivation. Higher root and white sugar yields were obtained in the study conducted at Płonne (with similar soil conditions to those at Bałcyny), but they were characterized by higher temperatures during the growing season. The lowest root yields in both experiments were obtained by fertilizing the organic beet with compost (66.1 t per ha in Bałcyny and 78.13 t per ha in Płonne), which were 10.8% and 8.5% lower than the conventional crop, respectively. Higher root yields in organic cultivation were obtained by fertilizing the sugar beet with FYM, which reduced the differences from conventional beet to 7.7% in the study in Bałcyny and 2.1% in the study in Płonne. Thus, the results showed no need to convert cattle FYM to compost. The highest root yields in organic cultivation were obtained by fertilizing the sugar beet with Bioilsa N 12.5 supplemented with mineral fertilization of K, Mg, and S (Patentkali). This fertilization provided a yield of 78.1 t of roots per ha in Bałcyny, which is a reduction in the yield gap to 1.4%, a statistically insignificant value. Moreover, in the study at Płonne, organic sugar beet fertilized with Bioilsa and Patentkali yielded 86.7 t of roots per ha, compared to 85.6 t per ha of conventional beet, so a yield gap was not seen here. The choice of varieties was also of great importance for root and pure sugar yields in both farming systems. The lowest yields were obtained from the Eliska variety, and at Bałcyny, a change of beet cultivar to Jampol increased the organic root yield from 68.8 t per ha to 76.0 t per ha, while reducing the yield gap from 10.1% to 2.2%. At Płonne, replacing the Eliska variety with Jampol reduced the yield gap between organic and conventional roots from 6.6% to 0.3%.

Sugar beet (Beta vulgaris L.) is the world’s second most important source of sugar, yet its production is seriously threatened by the beet cyst nematode Heterodera schachtii. Managing this pest remains a major challenge, especially where the use of chemical nematicides is limited or prohibited, highlighting the need for sustainable biological alternatives. This study evaluated the edible fungus Pleurotus ostreatus as a potential biocontrol agent against H. schachtii. Several offspring strains derived from a wild parental isolate (Po4) were tested in both pot and field experiments. In pot trials, mycelial application to fallow soil reduced nematode populations by 46.9–71.3%, while in soils cultivated with sugar beet, reductions of 26.2–32.5% were observed. Field experiments conducted over two consecutive years confirmed the nematode-suppressive activity of the Po4 strain, with population decreases of approximately 45–48% in fallow soil and 7–21% in sugar beet plots, whereas control plots exhibited 2–3-fold increases. These consistent trends indicate that P. ostreatus mycelium effectively limits nematode proliferation under both controlled and field conditions. The findings demonstrate the potential of P. ostreatus as an environmentally sound and practical component of integrated pest management systems, offering sugar beet producers and breeding programs a novel biological approach to sustainable nematode control.

Sugar beet (Beta vulgaris L.) is the second sugar crop in the world. One of its pests is Heterodera schachtii, a root-knot nematode. Protection against this pest is challenging and requires the integration of various methods, including biological ones. The possibility of using Pleurotus ostreatus as a biological factor in the protection of sugar beets presents an opportunity. Mycelia of this edible mushroom were tested in a pot laboratory test, showing a high protective potential. Results obtained by application to the fallowed soil revealed a 71.3% reduction in the nematode population. When sugar beets were sown in pots, the results were not as high. However, in this favorable pest environment, the tested mycelia could inhibit and even decrease the nematode population by up to 32.5%, in contrast to unprotected pots, where an over 200% increase in H. schachtii population was achieved. In the field experiment, where a single strain was tested, the results were similar; however, the protective activity of the mycelium was lower. On fallow soil, the reduction was 45.4-48.4%, while on sugar beet plots no increase in the H. schachtii population was observed, and its reduction was 7.5-21.4%.

The vegetative mycelium of Pleurotus ostreatus (oyster mushroom) exhibits the ability to reduce nematode populations. This property may be utilized in integrated management programs targeting harmful nematodes such as Heterodera schachtii, a major pest of sugar beet crops. In addition to sugar beet, many other plant species serve as hosts for this nematode; susceptible plants promote H. schachtii development and population growth. Current control strategies rely on integrated plant protection methods, including the use of tolerant cultivars, fallowing, and trap crops such as oilseed radish and white mustard. This study aimed to determine whether sugar beet cv. Janetka or nematocidal plants—oilseed radish cv. Romesa and white mustard cv. Bardena—affect the nematocidal activity of P. ostreatus mycelium when applied together. Specifically, the influence of root or seed secretions from these plants on the activity of ten P. ostreatus mycelial strains was assessed using the model nematode Caenorhabditis elegans and the target pest H. schachtii. Experiments were conducted under laboratory conditions on water agar media colonized by P. ostreatus mycelium. Seeds or root exudates of the tested plants were applied to the mycelial surface. Following incubation, nematode mobility (C. elegans) and cyst entwining by the mycelium (H. schachtii) were evaluated, along with the ability of the mycelium to produce toxocysts. The results indicated that trap plants did not significantly alter the nematocidal activity of the mycelium. However, certain mycelial strains were slightly stimulated by seed diffusates or root exudates. Oilseed radish moderately influenced the nematocidal activity of four mycelial strains against C. elegans, whereas in the case of H. schachtii, similar effects were observed with white mustard. Mycelial elimination of H. schachtii occurred through cyst entwining, which was generally more effective in the presence of plant exudates. Overall, the findings demonstrate that incorporating trap crops such as oilseed radish cv. Romesa or white mustard cv. Bardena, as green manure in crop rotation systems, does not interfere with the nematocidal activity of P. ostreatus mycelium and simultaneously may enrich the soil with nutrients. The study further confirms that P. ostreatus maintains its ability to effectively entwine and eliminate H. schachtii cysts even in the presence of sugar beet, supporting its potential role as a biological control agent. To our knowledge, this is the first experiment that integrates the activities of trap plants and sugar beet with the nematocidal effects of P. ostreatus mycelium.

The vegetative mycelium of Pleurotus ostreatus (oyster mushroom) exhibits the ability to reduce nematode populations. This property may be utilized in integrated management programs targeting harmful nematodes such as Heterodera schachtii, a major pest of sugar beet crops. In addition to sugar beet, many other plant species serve as hosts for this nematode; susceptible plants promote H. schachtii development and population growth. Current control strategies rely on integrated plant protection methods, including the use of tolerant cultivars, fallowing, and trap crops such as oilseed radish and white mustard. This study aimed to determine whether sugar beet cv. Janetka or nematocidal plants—oilseed radish cv. Romesa and white mustard cv. Bardena—affect the nematocidal activity of P. ostreatus mycelium when applied together. Specifically, the influence of root or seed secretions from these plants on the activity of ten P. ostreatus mycelial strains was assessed using the model nematode Caenorhabditis elegans and the target pest H. schachtii. Experiments were conducted under laboratory conditions on water agar media colonized by P. ostreatus mycelium. Seeds or root exudates of the tested plants were applied to the mycelial surface. Following incubation, nematode mobility (C. elegans) and cyst entwining by the mycelium (H. schachtii) were evaluated, along with the ability of the mycelium to produce toxocysts. The results indicate that trap plants did not significantly alter the nematocidal activity of the mycelium. However, certain mycelial strains were slightly stimulated by seed diffusates or root exudates. Oilseed radish moderately influenced the nematocidal activity of four mycelial strains against C. elegans, whereas in the case of H. schachtii, similar effects were observed with white mustard. The mycelial elimination of H. schachtii occurred through cyst entwining, which was generally more effective in the presence of plant exudates. Overall, the findings demonstrate that incorporating trap crops such as oilseed radish cv. Romesa or white mustard cv. Bardena, as green manure in crop rotation systems, does not interfere with the nematocidal activity of P. ostreatus mycelium and simultaneously may enrich the soil with nutrients. The study further confirms that P. ostreatus maintains its ability to effectively entwine and eliminate H. schachtii cysts even in the presence of sugar beet, supporting its potential role as a biological control agent. To our knowledge, this is the first experiment that integrates the activities of trap plants and sugar beet with the nematocidal effects of P. ostreatus mycelium.