Fruit growing
and viticulture of South Russia

Annotation

The intensive production of fruits, directed on obtaining of stable and high-quality crops, causes the necessity to increase the resistance of cultivars to diseases. Under the modern conditions of rapid climat change, caused by anthropogenic, including agricultural environmental contamination, the protective and adaptive characteristics of the plants are reducing, and this factor determines the need to obtain the varieties of fruit crops adapted to a wide range of changing external conditions both abiotic and biotic. The article presents the data of early apple seedling selection for resistance to the two apple-tree dominant fungal infections: to scab under artificial infestation and to powdery mildew on a natural background. The object of research is the hybrid apple seedlings resulting from deliberate crossbreeding of K15461 sample of MOSVIR collection, that is relatively steady to both pathogens, with the susceptible Fuji cultivar. In 36% of the samples a scab lesions were not identified, 39% of the seedlings are resistant to a powdery mildew, according to the two years of the evaluation. 3 seedlings showed the resistance to the two pathogens, their share is 11 %. The evaluation of the plant also on complex features "cultivation" made it possible to identify the most of them as significant for breeding. The obtained results indicate a high prospect of using of K15461, as well as hybrid plants obtained in the combination of crossing of K15461 × Fuji, as donors of resistance to scab and powdery mildew. The hybrid seedlings can be used for study directed to the identification and mapping of new genes for resistance of apple plants to these pathogens.

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.