Pigeon pea sterility mosaic virus

Pigeon pea sterility mosaic is a significant viral disease caused by the Emaravirus cajani. This pathogen is known to cause severe yield losses in pigeon pea (Cajanus cajan) crops globally, particularly in semi-arid tropical regions. As a systemic viral infection, it disrupts the physiological development of the plant shortly after inoculation.

The primary host for this virus is the pigeon pea, a crucial legume crop for food security. The virus is categorized under the Emaravirus genus and typically spreads through plant-to-plant contact mediated by insect vectors. The infection is persistent, meaning once a plant is infected, it remains a reservoir of the virus throughout its lifecycle.

Symptoms of the disease are characterized by leaf mosaic, mottling, and ring spots. A hallmark sign is the phenomenon of "sterility," where infected plants fail to produce flowers or develop deformed floral parts, leading to an almost total loss of pod production. Infected plants also tend to be stunted with bushy growth due to shortened internodes.

Transmission of the virus is exclusively facilitated by the eriophyid mite (Aceria cajani). The mite acquires the virus from infected plants and transmits it during feeding. Environmental conditions, such as high temperatures and relative humidity, play a critical role in the population dynamics of the mite vector, thus influencing the disease outbreaks.

Management and prevention of the sterility mosaic disease require an integrated pest management (IPM) strategy. Key practices include:

• Cultivation of resistant or tolerant pigeon pea varieties;
• Removal and destruction of infected host plants;
• Application of suitable acaricides to control the mite population;
• Ensuring crop rotation and maintaining host-free periods to break the viral cycle.