Dactylis mosaic virus

The pathogen responsible for this disease is the Dactylis mosaic virus (DaMV), a member of the Potyvirus genus. It is a systemic plant virus characterized by filamentous particles that interfere with the host's physiological processes. As a potyvirus, it relies on host cell resources for replication and can spread throughout the entire plant tissue.

The primary host for this virus is orchard grass (Dactylis glomerata). However, the disease also affects various other species of forage grasses, including fescues and ryegrasses. These grasses serve as both hosts and reservoirs for the virus, ensuring its survival from one season to the next in temperate climates.

Symptoms of the infection typically appear as a distinct mosaic pattern, light green to yellow streaks, and chlorotic mottling on the leaf blades. Affected plants often exhibit stunted growth, reduced biomass, and in severe cases, the foliage may show significant yellowing and tissue necrosis. These signs are most observable during periods of active grass development.

The virus is transmitted by several aphid species in a non-persistent manner. This means that aphids can acquire the virus from an infected plant and immediately transmit it to a healthy one during short feeding probes. Environmental factors such as mild winters and warm springs, which favor aphid population growth, significantly contribute to the widespread distribution of the virus.

The economic impact of this virus includes reduced yield of green forage and poor seed production. To mitigate the risk, agricultural practices such as using certified disease-free seeds and managing weed reservoirs around fields are essential. Additionally, integrated pest management focused on controlling aphid populations is necessary to limit the spread of the virus within forage grass stands.