Sweet potato chlorotic dwarf disease complex

Sweet potato chlorotic dwarf disease complex is a severe viral condition affecting sweet potato crops globally. It is typically caused by a synergistic interaction between the Sweet potato chlorotic stunt virus (SPCSV) and various potyviruses, most notably the Sweet potato feathery mottle virus (SPFMV). This interaction often leads to more severe symptoms than any single viral infection.

The primary host for this disease complex is the sweet potato (Ipomoea batatas). The virus infects the plant's vascular tissue, disrupting nutrient transport and photosynthesis. This results in significant yield reduction, as the storage roots fail to develop to their full potential, often becoming stunted or deformed.

Symptomatology involves severe chlorosis (yellowing) of the leaves, mosaic patterns, and extreme stunting of the vines. Due to shortened internodes, the plants appear bushy and compact. Infected plants exhibit a marked lack of vigor and an overall reduced growth rate compared to healthy plants in the same field.

The transmission of these viruses occurs primarily through infected planting material (cuttings) and via insect vectors. Whiteflies (Bemisia tabaci) and aphids are the most common vectors responsible for spreading the disease within and between fields. Environmental factors like high temperatures and sustained drought can exacerbate the stress on the plants, making them more susceptible.

Management and prevention focus on breaking the disease cycle. It is crucial to source clean, virus-indexed propagation material from reputable nurseries. Integrated pest management (IPM) is necessary to control whitefly populations. Furthermore, farmers should implement rigorous sanitation practices, including the removal of symptomatic plants and maintaining a clean fallow period to reduce the reservoir of viruses in the environment.