Mycelium of <em>Pleurotus ostreatus</em> Effectively Reduces the Population of the Sugar Beet Cyst Nematode <em>Heterodera schachtii</em>

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%.