According to the primary observation of plants and the results of the USDA laboratory analysis of provided samples, it is possible to conclude that there is an outbreak of tomato mosaic virus (ToMV) in Montana. It is an extremely contagious and serious plant pathogenic virus, a member of the family tobamoviridae , that belongs to the genus tobamovirus (Arinaitwe et al., 2018). Although ToMV is among the oldest described viruses that affect plants, it may be currently found in all continents despite the introduction of genetically modified resistant varieties. As a matter of fact, the seriousness of this virus’s outbreak is determined by its high virulence, easy dissemination, and undetectability. In other words, it is difficult to identify ToMV that spreads fast and easily, having a devastating impact on crops. In addition to tobacco, beans, and especially tomatoes that are highly susceptible to this virus, squash, potatoes, peppers, apples, pears, roses, cherries, and other 150 types of agricultural crops and weeds may be infected (Arinaitwe et al., 2018). In turn, similar to other plant viruses, ToMV does not cause infection or replicate in mammals, including humans. The symptoms of ToMV may be found at any stage of a plant’s growth, and all parts may be infected. In general, the manifestation and symptoms’ severity may vary in accordance with environmental conditions, the infected plant’s age, and the virus strain. The most common symptoms include leaf distortion, such as wrinkle, tiles, and leaflets’ curvature and reduction, chlorotic mosaic (light and darker green mosaic leaf mottle), defoliation, and general mottling. Other potential symptoms are fruits’ irregular ripening and discoloration, and systemic necrosis of vascular tissues (Creative Diagnostics, 2017). As a result, ToMV leads to serious losses and a reduction of yield. There are different methods used to detect the pathogen, including biological, molecular, and using indicator plants. In laboratory settings, the DAS-ELISA test on tomato seeds may be regarded as a highly efficient method of detection (Creative Diagnostics, 2017). In general, the etiology of ToMV depends on numerous ways of its spread. Thus, ToMV may appear on the farm through the following sources:   * Insects, including leafhoppers, aphids, cucumber beetles, and whiteflies (Grant, 2021);   * Division and cutting of infected plants – parts will be infected as well;   * Seeds of infected plants;   * The soil of infected plants debris;   * Human activity. Thus, the virus could appear on the farm from infected seeds brought from outside or leftover plant debris. In general, they may be regarded as the most common and main contagion if the cases of ToMV were previously observed, as well. In soil, ToMV is able to survive during the period of up to two years (Grant, 2021). In addition, it may be transmitted by people or insects, as the disease is traditionally spread via wounds caused by insect chewing, mechanical injury, and grafting (Grant, 2021). Moreover, the virus is easily spread on workers’ tools, hands, and clothes during traditional activities such as harvest, removing of suckers, and plant tying. As previously menti