Neopyrenochaeta root rot

Neopyrenochaeta root rot is a serious soil-borne fungal disease caused by species of the Neopyrenochaeta genus. This pathogen primarily invades the root system of various plants, causing decay and preventing the efficient uptake of water and vital nutrients, which leads to stunted growth and reduced crop yields.

The disease is most famously recognized for causing "pink root" in onions, but its host range includes a variety of other crops such as tomatoes, cucumbers, and peppers. Because the fungus thrives in the soil, it poses a significant threat to both open-field agriculture and greenhouse production systems.

The primary clinical sign of the infection is the discoloration of the roots, which transition from healthy white to pink, purple, or dark brown as the infection progresses. As the roots die off, the foliage typically exhibits chlorosis, wilting during peak sunlight hours, and overall plant decline, which is often mistaken for drought stress.

The pathogen is highly active in warm, moist soil conditions, with optimal development occurring at temperatures between 24 and 28 degrees Celsius. Neopyrenochaeta survives in the soil for extended periods via sclerotia (resistant resting structures) found on decaying plant debris. Transmission occurs mainly through contaminated water, infested soil movement, and non-sterile nursery substrates.

Effective disease management focuses on prevention rather than cure, as soil-borne pathogens are difficult to eliminate once established. Recommended strategies include long-term crop rotation, the use of resistant plant cultivars, and soil disinfestation techniques such as solarization or steaming in greenhouses. Proper irrigation management and improving soil drainage are also critical to reducing the incidence and severity of the disease.