Morphobiological development and distribution of oat (cereal) cyst-forming nematode (Heterodera avenae Woll.) in grain crops of Ukrainian southern steppe zone
Heterodera avenae Woll. affects grain crops and leads to severe economic losses in the areas of its distribution. The study was conducted to determine the species composition and distribution of Heterodera avenae Woll. in grain agrocenosis of the southern steppe zone of Ukraine. Nematological samples were taken according to standard and modified methods. Cysts from the soil were isolated by the decanting and sieving method. Production of temporary and permanent preparations determined the species composition of nematodes was carried out according to the generally accepted method. As a result of the conducted study, it was established that Heterodera avenae Woll significantly populated many grain crops in the Ovidiopolsky and Ivanovsky districts of the Odessa region. The number of Heterodera avenae in distribution areas significantly exceeded the economic threshold of harmfulness (ETH). At the same time, the symptoms of foci of suppressed plants are not always associated with infection with parasitic nematodes. One of the most pressing problems nowadays remains the improvement of existing and development of new mass nematological diagnostics of phytocenosis to identify foci of Heterodera avenae, its timely localization, and reduce the number population to an economically imperceptible level. It is necessary to have cartograms of the prevalence with the determination of the area of foci, the level of population of soil, and the species composition of cyst-forming nematodes, which should become the basis for differentiated selection and systematic application of various anti-nematode measures depending on their economic recoupment and environmental feasibility.