Fruit growing
and viticulture of South Russia
Phytosanitary condition of plants
The results of study on the harmfulness and spreaning of bacterial diseases of grapes in the agrocenosis of the Rostov Region are presented. The main harm to vineyards in Russia is caused by bacteriosis of berries and bacterial cancer. The manifestation of bacteriosis on grape berries in the Rostov Region was previously observed only in some years, the development of the disease was weak and had a focal character. In recent years, we have noted the expansion of its range and increasing of harmfulness. The disease manifests itself annually, but the degree of susceptibility varies by years and grape variety. Intensive development of the disease was observed in 2018. Plants of the Lakhedi Mezesh and Baklanovsky variety were most affected. No disease was noted in the varieties of Magia, Talisman. Tumor growths caused by the bacterium Agrobacterium Vitis and formed on the lignified parts of the bush, interfere with sap flow and nutrition of plants, reduce their productivity, durability and resistance to adverse conditions. The lifespan of vineyards directly correlates with their sparseness and the intensity of bacterial cancer (r = 0.79). The bushes with bacterial cancer, compared with healthy ones, have significant differences in the number of fruiting shoots (by 20-40 %), in yield (by 20-32 %), and in ripening of the vine (by 8-20 %). The deterioration of agrobiological and economic indicators in the infected plants can be explained by a significant deterioration in plant nutrition, not only due to a decrease in the volume of the conducting system due to vascular necrosis, but also due to the consumption of plastic substances on the growth of the cancerous tumor itself, which leads to the gradual depletion of the plant and its death. The main factor in the spread of bacterial diseases is human economic activity related to the reproduction of grapes, the production of grafted planting material, therefore, the most effective way to combat bacterial diseases is the procurement and propagation of healthy planting material.
The gray apple aphid is quite widespread on the territory of Russia and neighboring countries, however, there is still no its cartographic description in the literature in this territory, which is important in predicting the number of the vermins, and it became the task of our work. The paper presents a map of the distribution and zone of harmfulness of the Gray Apple or red-ball aphid Dysaphis devecta Walk. along the territory of Russian Federation and neighboring countries. It was created on the basis of analysis of literature sources, own observations and data on catching aphids by water traps in the fruit orchards. The information about the biology and ecology of the species is also presented and with the using of yellow water traps, the Northern border of the district was clarified. It runs along the Saint-Petersburg (Gatchina, Luga regions) Yaroslavl, then the line goes to East along the Northern border of apple orchards. No insects of this species were found in traps in the North regions. Grey Apple aphids are found in the Baltic area, Belarus, and the European part of Russia. The zone of Grey Apple aphids harmfulness includes the Southern and Eastern parts of Ukraine, Moldova, the North Caucasus and Transcaucasia, where the vermin periodic damage of plants is 2 points, in some foci the damage degree is 3 points. This is an industrial gardening area. The Grey Apple aphid is found in the Urals, in Western and Eastern Siberia, but the reproduction intensity of species in this territory is low due to the long winter period with temperatures below -20 ºC and low humidity. In some years, a small number of apple aphid is observed in Central Asia and Kazakhstan, where the summer temperatures above 30 ºC, with low humidity, have a detrimental influence the population.
Since 2013, in the Krasnodar Territory, fungi of the Fusarium Link genus have been the causative agents of rotting the apple fruits core, in 2019, 7 species of this genus have been identified as part of the pathocomplex. In order to effectively control the disease, in the pathogenesis of which a large number of species are involved, in vitro studies are required. It is necessary to achieve fast and guaranteed growth of each of the fungies. Significant variability of morphological and cultural characteristics of Fusaria is known during their cultivation under the influence of the composition of growing medium. In this regard, the selection for Fusarium fungi-pathogens of rot of the apple fruits core optimal for the cultivation of growing medium is actual. The studies were carried out by laboratorian and comparative analysis methods. We studied the growth of three pathogens of rotting the apple tree fruits core of the Fusarium Link genus in 10 growing medium. The radial colony growth rate and morphological and cultural characters were evaluated. As a result of studies in species F. semitectum (Mart.) Sacc., F. sporotrichioides Sherb. and F. solani (Mart.) Sacc. was found that not only the growth rate of the colonies was varied, but also their cultural characteristics depending on the growing medium. To cultivate the studied pathogenic fungi, carrot and tomato agar were isolated in the our experiments as universal medium on which the colony growth was most intense. Additionally, the growing medium were proposed for each species: for F. solani Murashige and Skoog medium; for F. semitectum medium Murashige and Skoog and wort agar; for F. sporotrichioides Nirenberg medium, potatoes-glucosal agar and wort-agar.
A method for assessing the virulence of the apple scab pathogen on unripe fruits is offered in the paper. The necessary conditions for its effective implementation were determined experimentally. It is shown that unripe fruits should be selected from the genotypes of apple-trees, which are controlled by chemical preparations for fungal diseases, in the "walnut" development phase. Surface disinfection of fruits is not effective if they are infected with rot agents in the garden, which may prevent of further analysis. The same conditions for the preparation and selection of unripe fruits should be observed when they are further stored for deferred experiments. The method was tested on 9 monospore isolates of Venturia inaequalis isolated from the apple variety of Renet Simirenko. The manifestation of symptoms of scab lesions was characterized by the development of diffuse spots of dark olive or dark gray color with mainly superficial development of pathogen mycelium. The studied isolates of V. inaequalis characterized by different levels of virulence and aggressiveness on different genotypes of the host plant, reflecting the high heterogeneity of the pathogen population. Pathogenicity of most isolates was higher for immature fruits from the variety Renet Simirenko, showing their adaptability to the variety from which they were isolated. Slightly lower virulence and aggressiveness of isolates was observed for the Idared apple variety. Only one of the 9 isolates of the scab pathogen was virulent to the species of Malus x purpurea var pendula ornamental apple. The study carried out showed the effectiveness of the proposed method, under the conditions of fruit selection, in assessing the virulence and pathogenicity of monospore isolates of the apple scab pathogen in laboratory conditions.
One of the limiting factors of consistently high yields with good quality are various diseases of the crop. For example, diseases caused by phytoplasmas can have a serious negative impact the quantity of the crop and its quality, which can further affect the quality of wine products and profits. Phytoplasmas are one of the most dangerous phytopathogens. On grapes, they are represented by two species Candidatus Phytoplasma vitis Flavescence dorée (causes Golden yellowing of grapes) and Candidatus Phytoplasma solani Bois noir. Many plant diseases that are thought to be caused by phytoplasmas were described before molecular genetic studies identified the various groups of phytoplasmas that cause these diseases. It is now possible to assess the relationship between the classification of phytoplasmas and specific plant diseases. Golden yellowing of leaves is a quarantine disease for the Russian Federation and the European Union and it causes a great damage to vineyards, so quick and accurate identification of this disease is very important. The main method for identifying phytoplasmas is real-time PCR (RT-PCR) with specific primer systems. The aim of our study was to compare the methods for extracting DNA from plant tissue affected by phytoplasma for further real-time PCR. This study showed that the samples isolated using the commercial kits "AgroDiagnostics" and "CytoSorb" show the similar results, while the sample isolated by the laboratory method based on the use of CTAB buffer showed higher and earlier peaks on the graph, which is important for detecting a small amount of pathogen in the test material and proves the greater effectiveness of this method of isolation.