Sweet potato

The plant is scientifically classified under the division Angiosperms, class Eudicots, order Solanales, family Convolvulaceae, and genus Ipomoea.

In agronomy, the sweet potato is not only a crop but also a major host for various phytopathogens, including viruses such as Sweet Potato Feathery Mottle Virus (SPFMV).

Pathogens can survive within the plant tissues, making the vegetative propagation method a high-risk factor for spreading infections across fields.

Identification often requires a combination of visual field monitoring and diagnostic lab testing to distinguish between nutrient deficiencies and actual pathogen infestation.

Viral diseases represent the most significant threat, causing systemic infection that leads to severe leaf distortion, mosaic patterns, and stunt growth.

Fungal diseases like Fusarium oxysporum cause vascular wilt, significantly reducing the vigor and tuber size of the crop.

Black rot (Ceratocystis fimbriata) causes dark, sunken lesions on tubers, rendering them unmarketable and acting as a persistent source of inoculum.

Soft rot, caused by various bacterial species, is common after harvest when tubers are stored in poorly ventilated or excessively humid conditions.

Total yield loss can occur if infected vines are used as cuttings for consecutive planting seasons, as the pathogen load increases exponentially.

Active development of most pathogens begins during the high-temperature months when the vines cover the soil, creating a favorable microclimate for fungi.

Viral transmission is highest during the peak activity of insect vectors, which typically occurs mid-season when pest populations reach their zenith.

Storage-related diseases begin their cycle during harvest if the tubers are damaged, allowing spores to enter through small skin abrasions.

Early season symptoms often appear in the nursery or immediately after transplanting, indicating that the source material was already infected.

Climate factors such as heavy rainfall can trigger the spread of soil-borne pathogens like Fusarium throughout the planting area.

• Chlorotic or yellowing leaves, often exhibiting distinct mosaic patterns along the veins.
• Stunted development, with plants failing to produce adequate foliage or healthy storage roots.
• Dark, circular, or irregular sunken spots on the tuber surface.
• Internal discoloration or dark ring patterns visible when cutting through the tuber flesh.
• Rapid wilting of vines despite adequate moisture levels in the surrounding soil.

Leaf curling or puckering is a classic sign of viral stress, often seen in sensitive sweet potato cultivars.

Dark patches on tubers often have a powdery appearance if fungal sporulation is occurring on the surface.

Significant differences in growth uniformity across the field are key indicators of a widespread pathogen issue.

A foul odor near stored tubers is a distinct sign of advanced soft rot caused by secondary bacterial colonizers.

The primary control measure is the use of disease-free, meristem-derived planting material to ensure a clean start for the crop.

Integrated pest management (IPM) is essential to control insect vectors such as aphids and whiteflies, which are the primary spreaders of viral diseases.

Rigorous sanitation of farm tools and storage facilities helps to minimize the transmission of pathogens between seasons and batches of produce.

Proper curing of tubers after harvest (maintaining high humidity and warmth for a few days) is vital to heal wounds and prevent fungal entry.

Rotation with non-host crops and maintaining a healthy field environment prevents the build-up of soil-borne pathogens over multiple years.