The role of abiotic and anthropogenic factors in the development of Alternaria leaf spot on potato plantings in the North-West of Russia

Abstract

For effective control of the phytosanitary state of agrocenoses, it is important to have knowledge of the influence of abiotic and anthropogenic factors on the population density of pests, weeds and the development of diseases. Among all the factors influencing the development of Alternaria leaf spot in potato planting in the North-West of Russia, the most significant was the influence of weather conditions (55.5%). The intense development of this illness occurred in the years with the high average diurnal temperatures in the second and third decades of June along with the high level of precipitation in the first decade of July. The contribution of mineral nutrition and the integrated plant protection system turned out to be unequal, which accounted for 9.6 and 0.9%. At the same time, in some years, the application of mineral fertilizers determined the development of potato Alternaria leaf spot by 11.6–87.5%, and the implementation of protective measures – by 1.2–17.6%. The strong development of Alternaria leaf spot was influenced by the increased air temperatures in the second and third decades of June, combined with abundant humidity in the first decade of July. The introduction of complete mineral fertilization led to a significant decrease in the development of Alternaria leaf spot in potato plantings, while the effectiveness of fungicidal treatments was not high enough.