Mucor plumbeus

Mucor plumbeus is a common soil-borne zygomycete fungus known to cause significant decay and mold in various agricultural and horticultural products. As a saprotrophic organism, it primarily thrives on dead organic matter but can become an aggressive opportunistic pathogen, especially when plants are weakened, damaged, or stored under inappropriate conditions.

This fungus exhibits a wide host range, frequently affecting seeds of cereals and legumes, which leads to poor germination rates. Furthermore, it is a major concern in the post-harvest industry, attacking stored vegetables such as potatoes, carrots, and onions, as well as soft fruits like strawberries and tomatoes. It thrives in high-humidity environments where it can easily colonize the surface and interior of produce.

The primary symptom of a Mucor plumbeus infection is the rapid appearance of a fluffy, lead-gray or dark-brown mold growth. As the mycelium spreads, the infected tissue loses its structural integrity and becomes soft and watery. A distinct, musty odor is often associated with the breakdown of the plant tissue, signaling that the produce is no longer suitable for consumption or commercial use.

The development and spread of this mold are heavily favored by high moisture levels, typically exceeding 85%, and moderate temperatures ranging between 20°C and 25°C. The spores of the fungus are highly resilient and easily dispersed via air currents, contaminated irrigation water, and handling equipment. Poor ventilation in storage facilities is often the primary driver of rapid infection spread among stored goods.

Management strategies focus on prevention rather than cure, as the mold is difficult to eliminate once established. Key practices include: maintaining proper air circulation in storage units, keeping humidity levels low, and avoiding mechanical damage to fruits and roots during harvesting. Pre-harvest treatment with fungicides and rigorous sanitation of farming tools are essential for mitigating the risk of Mucor plumbeus outbreaks.