Soil rot of sweet potato

Soil rot, also known as pox or Streptomyces ipomoeae infection, is a significant bacterial disease affecting sweet potato crops worldwide. It is characterized by its ability to cause severe damage to the root system, often resulting in stunted plant growth and poor harvest quality.

The pathogen specifically attacks sweet potatoes and is capable of persisting in the soil for extended periods even in the absence of a host. It primarily invades the feeder roots and the developing storage roots, causing significant disruption in the plant's ability to absorb water and nutrients.

Symptoms are usually visible at harvest, appearing as dark, sunken lesions or craters on the surface of the tuberous roots. In severe cases, the tips of the feeder roots may rot away, leaving a stubby root system that makes it impossible for the plant to produce a viable or marketable yield.

The severity of soil rot is highly dependent on environmental conditions, particularly soil pH and moisture. The disease thrives in alkaline soils and during dry periods, which allow the bacteria to proliferate more effectively compared to moist or acidic soil environments.

Preventive strategies are the only effective way to manage soil rot. Producers should focus on maintaining a slightly acidic soil pH, avoiding the introduction of contaminated soil or tubers to clean fields, and practicing long rotations of at least 3-5 years with non-susceptible crops to reduce the pathogen population.