Efficiency of application of the ethanolic and СО2-extracts of noxious plants to control number of wireworms in sunflower sowings

The mostly cultivated crop in the Krasnodar region is sunflower, which seedlings are damaged a lot by larvae of bugs from a family Elateridae. Wireworm is quite spread soil pest, so seed treatment with pesticides is an obligatory action for plant protection. However, there are some alternatives to the pesticides; one of them is usage of natural plant toxins containing different types of chemical combinations, such as alkaloids, terpenes, essential oils, etc. Many plants contain toxins characterized with repellent qualities or highly toxic matters - phytotoxins that serve as a natural protection of the pests. The purpose of the research is to study the effectiveness of extracts from noxious plants that are used for treatment of sunflower seeds as an alternative method to decrease wireworm damages of the crop sowings. The researches were conducted in the central agricultural and climatic zone of the Krasnodar region in the V.S. Pustovoit All-Russian Research Institute of Oil Crops (Krasnodar) in 2014-2016. In a vegetative experiment, the plants damage on a plot sown with seed treated with the plant extracts was equal to 10-20%, and in control one - 40%. Application of the СО2-extract of tobacco dust proved 100% protection of sunflower plants against damage and death. In variants with seed treatment with ethanolic extracts of leafy spurge (Euphorbia virgata Waldst. et Kit.) and greater celandine (Chelidonium majus L.), number of died wireworms was the biggest and reached up 75%. The results of field experiments showed the sunflower seed treatment with the ethanolic and CO2-extracts of plants provided sunflower plant population of 73.185.4% of a norm at an average wireworm number of 8.5 pcs/m2. The biological effeciency of the extracts was 52.2-74.0%, it was highest at the variant with seed treatment with the ethanolic extract of greater celandine. The sunflower seed treatment with the ethanolic extract of greater celandine, and the СО2-extract of tobacco dust allowed obtaining a maximal saved yield - 0.11-0.17 t/ha.