Urd bean

Urd bean (Latin: Vigna mungo) is a highly nutritious grain legume belonging to the Fabaceae family. While "Urd bean" identifies the crop itself, it is prone to significant yield losses due to various pathogens. The most destructive threat to this crop is the Mung bean yellow mosaic virus (MYMV), which affects plantations globally.

The causal agent is a bipartite begomovirus that relies on the whitefly (Bemisia tabaci) as its primary vector. The virus is transmitted in a persistent circulative manner, meaning that once the whitefly acquires the pathogen from an infected host, it remains infectious for a long period, posing a constant threat to healthy plants.

The primary clinical signs of the disease include characteristic mosaic patterns of yellow and green patches on the leaves. As the disease progresses, the chlorotic areas expand, and the leaves may become thickened, leathery, and distorted. Infected plants usually exhibit severe stunting and produce few or no flowers, leading to total yield failure.

The environmental conditions favoring the disease are high temperatures and humidity, which promote the rapid multiplication and migration of the whitefly population. Furthermore, the presence of alternative host weeds in and around the field serves as a year-round reservoir for the virus, ensuring a continuous source of infection for new plantings.

The economic impact of the virus is severe, often resulting in complete harvest loss in susceptible varieties. Integrated pest management (IPM) is essential for effective protection:

• deploying resistant or tolerant cultivars;
• eradicating weed reservoirs;
• applying systemic insecticides to suppress whitefly populations;
• using yellow sticky traps for monitoring;
• implementing proper crop rotation and field sanitation.