Dematophora root rot

The causal agent of this disease is the fungus Dematophora bunodes, often classified as Rosellinia bunodes. It is a severe soil-borne pathogen responsible for white root rot, which affects a variety of perennial crops. The fungus survives in the soil through thick mycelial strands and sclerotia, allowing it to persist in agricultural lands for many years.

This pathogen primarily targets woody plants, including fruit trees, citrus, coffee, tea, and various ornamental species. Because it spreads through the soil and direct root-to-root contact, it is particularly destructive in high-density orchards and plantations where plant roots are closely intertwined.

Key symptoms include stunted growth, chlorotic (yellowing) foliage, and progressive branch dieback. When examining the root system, a white to gray fungal mat is typically visible on the bark of the roots. As the disease advances, the root tissue loses its structural integrity, becomes spongy and rotten, and eventually turns dark brown or black.

Conditions favoring Dematophora bunodes include poor soil drainage, excessive moisture, and suboptimal pH levels. The fungus thrives in heavy, compact soils where aeration is limited. It spreads not only through the growth of mycelial strands in the soil but also through the transport of contaminated soil by farm equipment or infested nursery stock.

Control and prevention strategies require a multi-faceted approach centered on cultural practices.

• Quarantining and removing infected plants with their entire root systems.
• Improving soil drainage and aeration through tillage and organic matter incorporation.
• Correcting soil acidity via liming if necessary.
• Ensuring only disease-free nursery stock is planted.