Pea leaf roll virus

The virus affects a wide range of legume crops, including peas, lentils, chickpeas, faba beans, and alfalfa. Alfalfa often serves as a primary reservoir for the infection under field conditions.

The virus is transmitted exclusively by aphids, most notably the pea aphid (Acyrthosiphon pisum). Transmission occurs in a persistent manner: the aphid acquires the virus by feeding on an infected plant and remains capable of transmitting it throughout its lifespan.

The virus localizes in the plant's phloem, which determines the nature of the systemic infection and disrupts the transport of nutrients from leaves to seeds and roots.

A distinctive feature of the pathogen is that it is not seed-transmitted; therefore, the source of infection is always infected perennial legumes or overwintering host plants.

The first visual signs of infection appear on the young, upper leaves of the pea plant. The edges of the leaflets begin to curl inward, taking on a characteristic spoon-like shape.

The leaf blades of infected plants often turn yellow (chlorosis), a symptom that is particularly prominent in the upper parts of the stem.

Infected plants exhibit significant stunting and growth delay compared to healthy specimens. Stems may become thinner and more fragile as the infection progresses.

Flowering in infected plants is delayed, and pod formation is often incomplete or significantly limited, leading to a visible decrease in yield components.

• Rolling of terminal leaf edges.
• Yellowing (chlorosis) of the upper foliage.
• Stunting and inhibited plant growth.
• Significant reduction in pod set.

The development and spread of the disease are directly correlated with the activity of aphid vectors. Warm and dry spring weather promotes rapid aphid reproduction.

The proximity of pea fields to perennial legume crops, such as alfalfa or clover, significantly increases the likelihood of virus infection spreading to the pea crop.

The migration of winged aphids during the pea's active growth stage (branching and flowering) is the primary driver for widespread infection within a field.

Temperatures optimal for aphid activity, ranging from 15 to 25 degrees Celsius, simultaneously create favorable conditions for the accumulation and spread of the virus.

Dense crop stands and the presence of weeds that serve as alternative shelters for aphids create a favorable microclimate for the disease to progress.

The primary damage is a substantial reduction in seed yield. The virus blocks the plant's ability to develop generative organs, resulting in empty or underdeveloped pods.

Early-season infection can cause yield losses ranging from 50 to 80 percent, making the crop economically unviable without effective management.

Seed quality is severely compromised; seeds from infected pods are often smaller, with reduced germination rates and lower seedling vigor.

Infected pea plants are more susceptible to environmental stressors, such as drought or secondary fungal infections, which further exacerbate the yield loss.

Economic losses arise not only from reduced output but also from the increased costs associated with applying insecticides to control vector populations.

The main strategy for control is spatial isolation. Planting peas away from perennial legume crops helps minimize the risk of initial infection from aphid migrations.

Monitoring aphid populations and applying insecticides when threshold levels are exceeded is essential to interrupt the virus transmission chain effectively.

Agronomic practices, including weed management both in fields and on field borders, are crucial to removing alternative hosts for both the virus and its aphid vectors.

The use of resistant or tolerant pea varieties is considered the most sustainable and effective long-term method for mitigating the impact of this virus.

Timely field scouting during the early growth stages is vital for detecting infection hotspots and taking rapid action to prevent further spread across the field.