Presented investigations results obtained during the 2010-2014, it was estimates more than 10 thousand varieties and hybrids resistant tomato breeding samples relative to the pathogen Alternaria. It was highlighted a special line, peculiar field relative stability in the conditions of Kiev region, which will be used in the selection process creating hybrids and varieties. In recent years in Ukraine abrupt climate changes are observed, which promote intensification and increased harmfulness of Alternaria on tomatoes. This disease is known as macrosporiosis, early blight, early blight, dry, dry concentric spot. The causative agent on tomatoes is a fungal pathogen Alternaria solani (Ell. Et Mart) Neerg. It is the most common form of Alternaria on tomato leaves but also causes disease on other plant organs: cotyledon and true leaves, petioles, stems, fruits. Yield losses from this disease are 20-30%, and 40-50%. Weather conditions affected significantly the development of this pathogen. The optimal conditions for its development is temperature of 24-28 ° C and humidity within 70-100%. During the growing season the agent reproduces asexually by means of conidia, that contributes to the rapid spread of the disease. According to source ecological classification of infectious diseases Alternaria referred to aerogenic infection (Chulkin, 1991). According to E.Vlasov and other scientists (1979) the agent affects weakly low capacity, sterile, medium and late samples with indeterminate bush type. In Ukraine genetic resistance of tomato to Alternaria studied poorly. This is due to the fact that in Ukraine the disease, though, was common, but it did not cause significant damage to tomato producers and had attracted the attention of plant pathologists to resistance factor to Alternaria controlled by one pair of genes with partial dominance susceptibility. Varietal resistance to this pathogen has not been reported. During the period of 2010-2014 years in the field it was evaluated more than ten thousand tomato varieties and hybrids of different eco-geographical origin in order to create a collection of sources for resistance to Alternaria solani (Ell. EtMart) Neerg. During the period of research for seven years weather conditions for plant growth and development and yield formation tomato fruits were quite colorful. As a result of research material selection on the basis of resistance to Alternaria was distributed in the following groups of samples: relatively stable (with the degree of development of the disease to 25%) – accounted for 0.1% of the number of analyzed; weakly sensitive (degree of disease from 25.1% to 37.5%) – 0.2%; medium sensitive (from 37.6 to 50.0%) – 2.2%; sensitive (from 50.1 to 75%) – 22.0%; highly sensitive (by 75.1% or more) – 75.4%. As seen from the above data evaluation of plant susceptibility to pathogen Alternaria resistant specimens were found. According to the results of phenological observations it was revealed that selected varieties and hybrids were relatively stable and slightly susceptible to Alternaria. They belong to the early and medium varieties of ripe, during their growing season range from 99-113 days and the yield of 50,2-82,0 t / ha (See the table). To study the nature of inheritance for resistance to pathogen Alternaria solani (Ell.Et Mart) Neerg and selection of resistant forms it was performed a series of crosses. Featured in nursery-field, relatively resistant varieties crossed with varieties evolving complex agronomic traits. In the studied combinations of resistance to the pathogen it was inherited dominant, intermediate or recessive traits. Obtained a new source, material was relatively stable and slightly susceptible to Alternaria, that is important for breeding nursery studyings. After analyzing the material studied during the last five years it has been noticed that the fruit tomato yield reached a fairly strong performance. So, the best examples of hybrid combinations reached 8.0 t / ha ( Fastovskii, Oberig. Zakaznyy samples), slightly lower – the Golden Fleece's line 10, Bojan's Dawn (7,9t / ha) and the lowest – Myrolyubivsky sample (7.6) (See the table).

In conclusion, the value of marketable tomato fruits, its recent presentation as well as its selection process was at 20-25 % respectively. Early samples were improved by more precocious forms (Zoren, Fastovskii, Zakaznyy 280х Zoren, Myrolyubivskyy). Biochemical composition of the samples also had the best essence with smaller percentage of 10-15 (in prototypes Hurricane's L.pimpenefolium, customized 280 х Dolya,) in which the dry matter content was 5.8 mg%, sugar 3 3 % ascorbic acid 28.9 %. Accordingly it had been obtained good results in the evaluation of prototypes of new pathogenic races of blight T0 and T1 Alternaria.

Key words: tomato, pathogen Alternaria, variety, branch, crossbreeding.