Potato leafroll virus

Causal agent and disease type. Potato leafroll virus (PLRV) is a member of the Polerovirus genus. This virus infects the phloem tissues of the host plant, causing significant disruption in the translocation of nutrients. It is a persistent, aphid-borne virus that remains in the vector for its entire lifespan after acquisition.

Host range and distribution. While potato is the primary agricultural host, the virus can also affect other members of the Solanaceae family, such as tomatoes and peppers. It occurs globally wherever potatoes are cultivated, with distribution strongly correlated with the presence and population density of its primary vector, the green peach aphid (Myzus persicae).

Symptoms and signs. The characteristic symptom is an upward rolling of the leaflets, starting from the lower leaves and progressing to the top. The affected leaves become thick, leathery, and often display a chlorotic or purplish discoloration. Plants infected from tubers show severe stunting and reduced yield, whereas plants infected during the current season may show symptoms only on the upper foliage.

Harmfulness and impact. The economic impact is profound, as PLRV can reduce yields by 50% or more. The virus induces a physiological condition in tubers known as 'net necrosis,' which causes brown, necrotic streaks in the flesh. This makes the tubers unmarketable and unsuitable for processing, resulting in significant financial losses for growers.

Control and prevention methods. Managing PLRV requires an integrated pest management strategy:

• Planting certified virus-free, high-quality seed potatoes.
• Eliminating volunteer potato plants and weeds that serve as virus reservoirs.
• Implementing rigorous aphid control programs using systemic insecticides.
• Selecting potato varieties with natural resistance or tolerance to the virus.
• Removing and destroying infected plants promptly to prevent further spread in the field.