The occurrence of rust on sunflower varieties in the conditions of the Krasnodar region

Sunflower rust is one the most widespread and dangerous diseases. Its pathogen is a highly specialized basidial fungus Puccinia helianthi Schw. of the order Uredinales. The cycle of fungus development on the sunflower includes three stages and five type of sporulation. Due to the fact that the stages of the pathogen development are not identical, the forms of manifestation of the disease are also different. Pathogen affects sunflower in all phases of growth and plant development. The article provides the results of long-term studies (2007-2017) on the prevalence of rust in the conditions of the Krasnodar region on the sunflower varieties of different maturity groups of VNIIMK breeding. The annual infestation of sunflower with rust was noted with a disease frequency from 16.0 to 52.0%, depending on the conditions of the year. The prevalence of rust on sunflower depends greatly on the maturity group of a variety. Middle-maturing sunflower varieties Flagman, Master and late-maturing silage variety Belosnezhny are the most susceptible to the disease. In particular years, the frequency of disease occurrence on these varieties was 54.8, 38.7, and 88.0%, respectively. Varieties of early-maturing group were the most resistant. Over the years of research, the disease occurrence on these varieties did not exceed 29.0%, with an average disease affection of 4.2%.