Plant-parasitic nematodes are considered major pathogens of sugar beet, causing significant yield losses both quantitatively and qualitatively. This study was conducted to determine the distribution and population density of plant-parasitic nematodes in sugar beet fields under the jurisdiction of the Jovain Industrial and Agricultural Company, located in Razavi Khorasan Province, an area playing a vital role in the country's sugar beet supply. A total of 150 soil samples were collected from the rhizospher of sugar beet plants across five regions: Neqab, Azadvar, Rah-Chaman, Hokmabad, and Qazlqarshi, in 2022. The samples were transferred to the laboratory to examine the distribution of plant-parasitic nematodes. Nematodes were extracted using the sieving and centrifugation method, while cyst nematodes were extracted using the Fenwick can method. Identification of cyst and root-knot nematodes was carried out based on morphological characteristics of juveniles and the shape of the vulval cone of females. Twelve nematode species belonging to eight genera and seven families within the superfamily Tylenchomorpha were identified: Heterodera schachtii, Meloidogyne javanica, M. incognita, Pratylenchus thornei, P. neglectus, Merlinius brevidens, Ditylenchus myceliophagus, Scutylenchus rugosus, Tylenchorhynchus annulatus, Helicotylenchus sp., Aphelenchoides sp., and Aphelenchus avenae. Cyst and root-knot nematodes were found at frequencies of 38.3% and 17%, respectively. The Neqab region showed the highest prevalence of cyst nematodes (93.3%), while Azadvar had the highest prevalence of root-knot nematodes (60%) among all surveyed areas. Given the widespread distribution and high population densities of cyst and root-knot nematodes in certain regions, the implementation of management strategies is recommended to prevent their further spread and reduce their populations in sugar beet fields.
