Fruit growing
and viticulture of South Russia

Annotation

The materials of the study of agrochemical and microbiological indicators of leached chernozem in the orchard agrocenosis and field crop rotation are presented. The peculiarities of the distribution of the main elements of plant nutrition and organic matter by layers in the upper part of the soil profile, depending on the type of cultivated crop, are revealed. As a result of the evaluation of the main groups of microorganisms of leached chernozems, 830 strains of pathogenic and conditionally pathogenic micromycetes were identified, among which Aspergillus spp. and Penicilium spp. predominate. The number of micromycetes in the studied areas differs slightly, however, in the upper layer (0-10 cm) of soils under the garden cenosis there is a sharp increase in them. It has been established that in the soils of the orchard cenosis there is a fivefold decrease in the number of bacteria in comparison with soils in the conditions of field crop rotation. The number of bacteria gradually decreases with depth. Correlations of the total number of fungi strains and colony-forming units of bacteria on the content of organic matter, nutrition elements, the total amount of salts and the reaction of the soil environment have been established. A close correlation between micromycetes and bacteria (r = 0.99), humus (r = 0.95), mobile potassium (r = 0.93) and pH (r = 0.89) was revealed in the soils of orchard cenosis. There are no close correlations in the field crop rotation. Data on the ratio of bacteria and micromycetes indicate a higher suppressiveness of soils in the conditions of field crop rotation and the depletion of the microbial pool of soils of orchard cenoses. This indicates the development of the process of soil fatigue and a decrease in the resistance of leached chernozems to phytopathogens during prolonged cultivation of an apple orchard in a monoculture.

Annotation

With the climate change on the planet towards warming, the fungi of the genus Alternaria Nees became more active. Due to the prevailing climatic conditions, some species of this genus changed their status and acquired signs of facultative parasitism and complete parasitism on a number of cultivated plants, including the apple-tree. In vitro scientific studies are required to effectively control the disease, in the pathogenesis of which a large number of species are involved. At the same time, it is necessary to achieve fast and guaranteed growth of each of the fungus in the experiments. In this regard, the selection for fungi of the genus Alternaria, causative agents of apple fruits core rot, optimal for the cultivation of nutrient mediums is urgent. The studies were carried out by methods of laboratory and comparative analyzes. The growth of two strains of the causative agent of the apple fruit core rot of Alternaria alternata (Fr.) Keissl. on 12 nutrient mediums. Colony growth rate and morphological and cultural traits were assessed. As a result of research the strains of apple fruit core rot agent, a variation not only in the growth rate of colonies, but also in their cultural characteristics, depending on the compositions nutrient medium. A comparative study of the morphological and cultural characteristics of A. alternata strains FR20IV and FR20VI on various nutrient mediums made it possible to identify three universal mediums most suitable for their cultivation and identification, namely carrot, potato agars and Sabouraud's medium, according to the following criterions: ensuring the maximum degree of sporulation, rapid growth and development of the mycelium of the fungus, as well as easiness of preparation of revealed optimum cultural mediums.

Annotation

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.

Annotation

Over the past 15 years, the prevalence of pathogens of the genus Fusarium has increased in the gardens of the Krasnodar region, which are found both in the root rot pathocomplex and in the apple core rot pathocomplex. At present, much attention is paid to the biological method of plant protection, one of the directions of which is the use of microbiological drugs. In this connection, we studied the antifungal activity of microbiological preparations Rizoplan, Liq., Alirin B, WP, Fitosporin-M, P, Vitaplan, WP, registered on an apple tree to control scab, powdery mildew, moniliosis, as well as promising in relation to pathogens of rot roots and cores of apple fruits from the genus Fusarium � Trichocin, WP and Biocomposite, Liq. As a result of the study of the antifungal activity of microbiological drugs against fungi of the genus Fusarium, causative agents of rot of roots and fruits of the apple tree, both weak and very strong mycoparasitism were noted, but in most variants of the experiment, competition for the area of nutrition prevailed. Under the influence of some drugs, the shape, edge and color of the fungus colony changed. In general, for the entire sample of pathogens, the best bioagents were the antagonists of the drug Trichocin, WP, which suppressed all five strains with BE 50-90 % and showed hyperparasitism in one strain, as well as the drug Alirin B, Liq, which inhibited the growth of three strains with BE 56 -85 %, showing antibiosis or fungistatic antibiotic antagonism with the formation of a �sterile� zone.

Annotation

Studying the rot of the seed chamber leads to the appearance of a micocomplex of 7 species fungi: 5 species of Fusarium Link and 2 species of Alternaria Nees. Presence of species on varieties in different gardens were heterogeneous. The set of plant species was unique for every variety and garden. The most number of species of pathogenic fungi was found on the Idared variety in the Timashevsky district. Two species of Fusarium was first discovered as rot causing agent of apple fruits in the Krasnodar Territory � F. solani (Mart.) Sacc and F. semitectum Berk. & Ravenel. Both species were found in the Dinsky district: one � at the Red Delicious variety, and the second � at the Starkrimson variety. Infection of flowers at the same time with two or three pathogens, which later co-developed in the seed chamber of the fruit, was established. The species of F. sporotrichiodes Sherb. was the most common in pathocomplexes. A study of the morphological and cultural characteristics of isolates of selected species in this study showed that cultural characteristics corresponded to those described earlier for these taxonomic units. For some species, the differences in growth rate, height, structure and color of aerial mycelium were noted. Most isolates of the species F. solani, F. semitectum, F. proliferatum (Matsushima), A. tenuissima ex Nees et T. Nees: Fries, and A. alternata (Fries: Fries) Keissler were characterized by rapid growth rates. According to the structure of the colonial aerial mycelium, homogeneous isolates � species F. solani, F. semitectum, F. avenaceum (Fr.) Sacc and heterogeneous isolates � species F. proliferatum, F. sporotrichiodes, were found. The color of aerial mycelium in most cases was homogeneous.