Red root disease

The fungus Poria hypolateritia is the causative agent of the devastating condition known as red root disease. It is a soil-borne basidiomycete pathogen that specifically targets the root systems of long-term perennial crops. The infection leads to a progressive degradation of root tissues, ultimately causing the decline and mortality of the host plant.

The primary economic host for this pathogen is the tea plant (Camellia sinensis). Poria hypolateritia is a significant threat in tropical and subtropical tea-growing regions worldwide. The disease is known for its ability to persist in the soil for extended periods by saprophytically colonizing old roots and woody debris left in the ground.

The visual symptoms of red root disease include stunted growth, yellowing foliage, and progressive leaf drop, followed by branch dieback. When infected roots are exposed, they exhibit a diagnostic reddish-brown mycelial coating or strands (rhizomorphs). The inner woody tissue becomes brittle and necrotic as the fungus depletes the plant's structural integrity.

Environmental conditions that favor the disease include poorly drained soils with high moisture content and high organic matter levels. The fungus spreads primarily through root-to-root contact in the soil. Once a colony is established, it can expand radially, killing adjacent plants and creating expanding circular zones of infection within the plantation.

Management strategies focus on strict sanitation and prevention. This includes the complete removal of stumps and old roots during land preparation to eliminate the fungal reservoir. In existing plantations, it is crucial to isolate infected patches by digging deep trenches, preventing the spread of mycelium to healthy zones. Proper soil aeration and professional fungicide application are necessary to contain the outbreak.