Bean yellow mosaic virus

The virus particles are flexuous filaments containing a single-stranded RNA genome, which allows for efficient replication within the host cells.

BYMV is characterized by an exceptionally broad host range, infecting various legumes, ornamentals, and numerous weed species across different regions.

It survives in perennial leguminous plants, which act as reservoirs that facilitate the carryover of the virus from one growing season to the next.

In the field, the virus is primarily transmitted by various species of aphids in a non-persistent manner during brief feeding probes.

Symptoms typically appear as characteristic mosaic patterns, often with light and dark green mottling on the leaflets of infected lupin plants.

Leaves may show significant deformation, crinkling, or curling, which disrupts normal development and reduces the photosynthetic surface area.

Stunting of the entire plant is a common manifestation, with infected individuals remaining significantly smaller than healthy ones.

Severe infections may lead to necrosis, premature flower drop, and a drastic reduction in the number and quality of pods formed.

• Interveinal chlorosis
• Leaf distortion and curling
• Shortened internodes
• Reduced pod set and seed size

The prevalence of the virus is largely dependent on the population dynamics of aphid vectors, which thrive in warm and stable weather conditions.

Early spring infestation of weeds by aphids provides the initial source of inoculum, which is then moved to emerging lupin crops by winged vectors.

Higher temperatures generally accelerate the replication of the virus within the plant tissues, leading to faster development of symptomatic phases.

The proximity of lupin fields to other leguminous crops or wild patches significantly increases the probability of virus spread via insect migration.

Mechanical damage to plants during agricultural operations can facilitate secondary spread if tools are not properly disinfected.

The economic impact of the virus is significant, as it leads to reduced yields of both grain and green biomass, directly affecting profitability.

Infected seeds often exhibit poor vigor and low germination rates, leading to uneven stand establishment and weak early-stage plants.

The viral infection predisposes plants to secondary infections by fungi or bacteria due to a weakened defense mechanism.

Total crop failure may occur in cases of early and heavy infection, especially if sensitive varieties are used in high-risk areas.

The quality of the forage is diminished, which is a major concern when lupins are used for sustainable animal feeding programs.

Using certified, virus-free seed is the most effective way to prevent the primary introduction of the disease into new production areas.

Management of aphid vectors through targeted insecticide applications can reduce the rate of virus spread during the critical growth stages.

Maintaining a clean field environment by removing host weeds is essential to eliminate local reservoirs of the virus throughout the year.

Implementing proper spatial separation between new lupin plantings and existing leguminous crops reduces the migration pressure from aphids.

Breeding and planting resistant or tolerant cultivars remains the most reliable long-term solution for managing BYMV in large-scale agriculture.