Characteristics and polymorphism of certain qualitative signs of monosporius isolates of the apple scab pathogen

Apple scab is an economically significant mycosis of the main seed garden crop of the region. The study of the biological and population characteristics of the pathogen is an essential condition for the formation of reasonable protection system for apple orchards. Assessment of the fungus population structure can be carried out using phenotypic analysis of its pure cultures. The advantage of the method is its availability and the ability to study large samples. The effectiveness of this approach is determined by the use of easily analyzed and polymorphic qualitative morphological and cultural signs. Aim. Search and selection of signs of pure cultures of the pathogen, suitable for the study of its populations. Methods. The studies were performed on Venturia inaequalis (Cooke) G. Winter monosporic isolates obtained from the diseased leaves of last year's litter (ascospore stage) using the original technique. At the pure cultures reached one month of age, various qualitative morphological and cultural characteristics were evaluated, among which were found those that had alternative variant of appearance. The presence of one variant excluded the presence of another. Results. Characteristics of the isolates were characterized: the form, the density of the aerial mycelium, the degree of sporulation, the center color and its texture. Main conclusions. As a result of the evaluation of 180 monosporic micromycete cultures, two perspective variant for population research of the pathogen, related to the characteristics of the colonie’s center, were identified.

Venturia inaequalis, Venturia inaequalis, morphological and cultural signs, pure culture, phenotypic analysis, alternative variants of sign, polymorphism