BIOECOLOGICAL SUBSTANTIATION OF POPULATION''S DENSITY REGULATION OF APPLE POWDERY MILDEW UNDER STRESS WEATHER CONDITIONS
Krasnodar Region is one of the main regions of the Russian Federation on production of fruits and berries. Defeat of fruit crops by fungal diseases belongs to the factors limiting the orchards yield capacity and of production standard. The activator of mildew Podosphaera leucotricha (Ell. et Ev.) Salm. is in the group of the dominating pathogens capable to cause essential losses of apple harvest. The spreading and injuriousness of mildew are defined by the variety's susceptibility degree, weather conditions of plants vegetation, especially during the periods of the greatest susceptibility of an apple-tree to a disease, and also by a complex of the protective measures carried out in the fruit orchards. Due to the increase in frequency of stressful weather situations in the Southern region of Russia the urgent direction of research is definition of protection features of apple-tree orchards against mildew under the changing weather conditions. The changes in the bio-ecological features of powdery mildew pathogen of apple trees in the Krasnodar Region connected with a climate changes are identified by research of 2011-2015. The tendency of increase in the intensity of infection and the tendency of increase in the pathogen population's quantity at less responsive and resistant apple varieties are marked. It is shown that with increasing in number of stressful weather conditions the using of the resistant varieties to powdery mildew is not the main economically significant way to control the disease. It is proved that the creation of the apple's protection against powdery mildew should take into account the damage of trees by environment stress-factors. To prevent the explosive epiphytoties it is necessary to carry out the whole complex of the protective measures not only in the highly responsive varieties, but also in all groups of resistance varieties to disease.