Abstract
Nematodes are one of the most numerous and widely distributed groups of multicellular organisms on the planet. Phytoparasitic nematodes, particularly members of the genus Heterodera, pose a significant threat to agriculture, causing substantial crop losses in cereal crops. Soil-borne pathogens, including nematodes and fungal organisms, are an important but often underestimated factor limiting wheat yield. This study conducted a survey of the major wheat-growing regions of Kazakhstan (Almaty, Uralsk, Shortandy) to detect and identify phytoparasitic nematodes. Soil samples were collected using zigzag and diagonal sampling schemes, processed by sieve washing, and analyzed through light microscopy. Cyst-forming nematodes (Heterodera spp.) were identified, along with representatives from other genera: Aphelenchus, Aphelenchoides, Tylenchus, Filenchus, Pratylenchus, Parapratylenchus, Ditylenchus. Particularly high populations of harmful species were recorded in the Shortandy district and Almaty region. Additionally, in greenhouse conditions, the interaction between Heterodera avenaeand Fusarium culmorumon hard wheat variety Sham 3 was studied. It was established that simultaneous infection results in a yield reduction of 38.4%, significantly exceeding the losses caused by each pathogen individually. The findings emphasize the need for regular monitoring of soil pathogens and the implementation of integrated plant protection measures, including rational crop rotation planning and consideration of the phytosanitary state of the soil