DEVELOPMENT OF ALTERNARIA BLIGHT IN POTATO AGROCENOSES UNDER THE INFLUENCE OF STRESSFUL FACTORS

The article presents the data on potato agrocenoses affected by Alternaria blight under the influence of various factors that have a stressful effect on the host plant and contribute to the damage of the crop by the disease. It’s established that potato nematodes increase the plant susceptibility to the disease, promoting epiphytotic development of Alternaria at earlier stages of the crop ontogenesis. Under the conditions of a natural infectious load of Alternaria pathogens under the influence of weather conditions epiphytotic development of the disease was observed on plants of the early ripening variety Breeze – 75,0 %, moderate – of the mid ripening variety Skarb and mid-late variety Nara – 40.0 % and 35,0 %, respectively. In the republic, a high prevalence of the disease is observed in the plants of the studied varieties, varying on average from 62,0 to 100 %. From Alternaria spp. fungi the dominant species on potatoes are A. alternata (77,8 %) and A. solani (52,8 %). With a high prevalence of Alternaria blight, reaching on average 93.3–100 % for potato varieties, the dominance of A. alternata was established with a frequency of occurrence of 100 %.