Internal cork

Internal cork is a viral disease primarily affecting sweet potatoes (Ipomoea batatas), caused by the Sweet potato internal cork virus (SPICV). This pathogen is a member of the potyvirus family and is typically transmitted by aphid vectors, which move the virus from infected plants to healthy ones during the growing season.

The disease specifically targets the storage roots of sweet potatoes. It is notoriously difficult to identify in the field because the aerial foliage of the plant often remains asymptomatic, showing no signs of distress or chlorosis, which leads to the unexpected discovery of the disease during harvest.

The characteristic symptom is the development of hard, corky, dark brown or necrotic lesions within the flesh of the sweet potato. Upon cutting into the root, these spots appear as irregular hardened areas, significantly compromising the texture, flavor, and overall marketability of the produce.

Environmental conditions play a crucial role in disease dissemination. High aphid population density during warm and humid weather significantly increases the rate of transmission. Furthermore, the use of vegetative cuttings taken from previously infected storage roots ensures the persistence and spread of the virus within the farming system.

The disease causes substantial economic losses, as infected tubers are generally rejected by consumers and retailers. Effective management and prevention strategies include:

• Sourcing virus-indexed or certified disease-free propagation material.
• Implementing integrated pest management (IPM) to control aphid populations.
• Rogueing and destroying symptomatic plants as soon as they are identified.
• Practicing crop rotation to break the cycle of the virus in the field environment.