Infection of species of the genus Juglans L. by diseases and pests under the conditions of the non-black earth of the middle land of Russia

The results of assessing the susceptibility of species of the genus Juglans L. under the conditions of introduction in the non-chernozem zone of the European part of Russia are presented. The aim of the study is to investigate the characteristics of the susceptibility of species of the genus Juglans L. to diseases and pests in the non-black earth region of central Russia. Plantings of Juglans were examined in eight regions: Moscow, Vladimir, Kaluga, Moscow, Ryazan, Smolensk, Tver and Tula regions. The plants were damaged by 10 types of fungi, 1 type of bacteria. The walnut entomofauna is represented by 2 arthropod species. It was revealed that in the middle zone of the European part of Russia, J. regia is the most susceptible to fungal and bacterial diseases. Among the studied forms of J. regia and hybrids of J. regia with J. ailantifolia ssp. Cordiformis and J. regia with J. mandshurica , growing in the Kaluga and Tula regions, the most common fungal disease is leaf alternaria (the causative agent Alternaria alternata (Fr.) Keissl), the maximum degree of development is 16%. The development of fungal diseases is largely determined by weather conditions and geographically heterogeneous. It was established that a highly harmful disease in the south of Russia - marsoniasis (the causative agent of the fungus Marssonina juglandis (Lib.) Magn) - was recorded on the examined plants only once. Exposure to low freezing temperatures and sunburn at the end of February and the first ten days of March significantly increases the likelihood of intensive development of common (the causative agent of the fungus Nectria galligena Bres.) and black cancer (the causative agent of the fungus Sphaeropsis malorum Peck.). The low number of phytophages did not affect the general condition of the studied plants.