## 4 Discussion
### Control of Diseases and Pests on Jerusalem Artichoke Plants  
Jerusalem artichoke is affected by pathogens of various etiologies: bacteria, viruses and fungi. Furthermore, plants suffer from nonparasitic functional diseases caused by various environmental factors such as the lack of nutrients, in particular nitrogenous and phosphorus compounds, etc. [53]. Four types of bacteria periodically parasitize and develop as semi-parasites and saprophytes on Jerusalem artichoke in different areas of the distribution area. No bacterial diseases were found in the samples of our experiments. At present, Jerusalem artichoke viruses are not widespread, but due to abrupt changes in climatic conditions and associated plant stress, the number of viral pathotypes of Jerusalem artichoke may increase. Currently, nine viral and mycoplasma diseases are known. They occur in the form of spots, mosaics, the curly deformation of apical leaves, the corrugation of leaf blades, the overgrowth of and reduction in leaves, the deformation of the corolla and the sterility of seeds [1; 54]. We should mention that no viral diseases were found on Jerusalem artichoke samples in our research. In different areas of the distribution, Jerusalem artichoke were infected by 32 species of phytopathogenic fungi which periodically parasitize and develop as parasites, semiparasites and saprophytes. As for pathogens of stems and leaves, the most widespread ones were: sclerotiiasis (two types of pathogen--Jerusalem artichoke sclerotioxin (Sclerotinia sclerotorium (Lib,) Mass.) and rolfsi Sclerotium (Sclerotin _Rolfsii_ Sacc.)). Jerusalem artichoke Fimatotricha omnivora (_Phymatotrichum_ = _Ozonium omnivorum_ ([PERSON])[PERSON]) and powdery fungi--powdery mildew (_Erysiphe cichoracarum_ DCF _helianthi_ Jacz.) should be mentioned [1; 55; 56]. In July, a slight infestation of leaves with powdery mildew (1-3%) was noted (Figure 6). In this case, the plant damage was 1-10% of the leaf surface in the form of single spots on individual plants, which corresponds to 8 points. Among plants heavily diseased were early cultivars (Skorospelka and Blank Brekos) for up to 14-15% of leaves, mid-early cultivars (Vylgortskiy and Nadezhda) for up to 11-12% and mid-ripening cultivars (Dieticheskiy, Kaluzhskiy, Nakhodka, Podmoskovniy and Sireniki) for up to 8-12%. Late-ripening plant (Interes, Interes 21, Novost VIRa and Spindle) varieties were slightly affected up to 5-7%. The least affected plants were mid-season varieties (Korenevskiy, Podmoskovniy and Violet de Rense) and late Tadzhikskiy varieties--up to 1-4% of leaves. In this case, the damage of plants was 1-10% of the leaf surface in the form of single spots on individual plants, which corresponds to 8 points. Plants of the following cultivars were the most affected by powdery mildew in the third ten-day period of September: Kaluzhskiy, Novost VIRa and Spindle (24-28% of leaves). Plants of the following cultivars were slightly affected: Interest, Interest 21 and Korenevskiy (7-9%). In this case, the damage to plants was 1-10% of the leaf surface in the form of single spots on individual plants, which corresponds to 8 points. Almost all leaves were clean in the cultivars Tadzhikskiy and Violet de Rense (2-3%). The average number of plants affected by powdery mildew was 1.6% in July, 8.0% in September and 13.3% in October. Therefore, if Jerusalem artichoke is grown for green fodder, then it is better to move the aboveground mass before the third ten-day period of September in order to avoid serious leaf damage due to powdery mildew. However, it can be noted that leaf damage may be up to 95... 99% in thick plantings [15; 23]. The destructiveness of JA leaves with powdery mildew on space plantings was also reported less by other researchers [14; 16]. The pest infestation assessment was carried out on the basis of a plant visual examination in the registration plot.