Alfalfa mosaic virus (sobemovirus group)

Pathogen and disease type. The causative agent of the disease is Sobemovirus plyv, a virus from the sobemovirus group. This is a viral disease characterized by systemic infection, which penetrates the plant's vascular system and impairs essential metabolic processes such as photosynthesis and protein synthesis. The virus exhibits high stability in the environment, which significantly complicates agricultural control efforts.

Susceptible crops. The primary host for this pathogen is alfalfa (Medicago sativa). In some cases, the virus may affect related legume species used in forage production. The wide host range and the ability to overwinter in dormant plant parts make this virus a significant threat to perennial agroecosystems and sustainable forage cultivation.

Symptoms and signs of infection. Initial symptoms appear as chlorotic spotting and a mosaic pattern on the leaf blades. As the disease progresses, leaf deformation, stunted shoot growth, and general bush depression are observed. Internodes are often shortened, causing the plant to develop a dwarf, compact appearance, which is particularly noticeable during periods of active vegetative growth.

Development and spread conditions. The primary vectors for virus transmission under field conditions are sap-feeding insects, such as aphids and certain thrips species. Additionally, the infection spreads mechanically during mowing, via contaminated harvesting equipment, and through the direct contact of damaged tissues between healthy and infected plants.

Damage and control measures. The disease significantly reduces green biomass yield, decreases hay quality, and shortens the longevity of the stand, leading to thinning of the crop. Control measures include:

• Using resistant alfalfa cultivars.
• Managing insect vectors through systematic insecticide application.
• Maintaining spatial isolation between new fields and older, infected areas.
• Disinfecting harvesting machinery and tools to prevent the mechanical transfer of the virus.