Hops are a dioecious plant, grown in plantations called hop fields. Female plants are mostly used in brewing, hop bitters are indispensable as they give the beer a taste. As a hop producer, Slovenia ranks fourth in Europe and fifth in the world. Cultivation is threatened by many pathogens, among which viruses are very important. They affect the amount of yield and the content of alpha acids. Apple mosaic virus (ApMV) is one of the most important and occurs worldwide. Signs of infection appear on the leaves as chlorotic ringspots. ApMV has no known vector and spread is most likely trough mechanical transmission or root grafting. Hop mosaic virus (HpMV) also occurs worldwide, more commonly in latent form, but chlorotic mosaics on leaves may be visible on sensitive cultivars. The main vector of the virus is the damson-hop aphid. Healthy plant material is essential to prevent the spread of infection. The serological immunoenzyme ELISA method is most commonly used to detect ApMV and HpMV infections. The aim of the master's thesis was to show the extent of re-infections of hop plants, after planting with virus-free seedlings of the ‘Aurora’ variety, according to the age of the hop yard and the spatial distribution of the infection, and mixed infections with both viruses. We found out that the level of infection with the viruses is different. There are more infected plants with the HpMV virus, the infection is more dispersed and consequently more plants are infected. The spatial distribution of infection between viruses is different. This is influenced by transfer vectors. HpMV infection occurs in islands and with ApMV in lines. We found one plant that was infected with both viruses. New infections are also visible.
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