Gilbertella rot

As a facultative parasite, the fungus thrives on decaying organic matter but can easily switch to infecting healthy plant tissues if an entry point is available, such as a wound or a bruise.

The biological cycle of the fungus includes the production of sporangia, which release countless airborne spores. These spores possess high dispersal efficiency, enabling the fungus to spread rapidly throughout storage facilities.

Genetic recombination occurs when compatible mating types meet, leading to the formation of zygospores. These thick-walled structures ensure the survival of the fungus in soil and debris during off-seasons.

The fungus secretes pectinolytic enzymes that quickly break down the middle lamella of plant cells, leading to a rapid collapse of tissue structure, which is a hallmark of this rot.

The first signs of infection include the appearance of small, water-soaked spots on the surface of the fruit. These spots expand rapidly, causing the affected tissue to become soft and mushy.

Under conditions of high humidity, a white, fluffy mycelium develops on the surface of the lesions. Over time, this mat becomes speckled with dark, pinhead-sized sporangia, giving it a gray or brownish appearance.

A distinct, sharp, acidic odor often accompanies the decay, as the fungus promotes active fermentation within the tissues of the affected host.

Internally, the fruit tissue undergoes a total loss of structural integrity, effectively liquefying. Despite this internal liquefaction, the outer skin may remain intact for some time, masking the severity of the rot.

Symptoms often originate from mechanical injuries, such as stem scars, punctures, or insect feeding sites, where the fungal spores successfully colonize the exposed plant cells.

High relative humidity, typically exceeding 85-90%, is the most critical factor for the rapid development of Gilbertella rot. Moist surfaces provide the necessary environment for spore germination.

The pathogen thrives in temperatures ranging from +20°C to +30°C. Warm conditions significantly accelerate the rate of mycelial growth, turning small infections into total fruit decay in a matter of days.

Temperature fluctuations that cause condensation or «sweating» on stored fruits provide the ideal moisture layer for the pathogen to establish itself.

Poor aeration in storage rooms allows for the buildup of stagnant, humid air, which promotes the spread of spores and the development of new infection centers among healthy produce.

Mechanical damage during harvest or transport is a major predisposing factor, as the fungus is primarily an opportunistic invader that cannot penetrate healthy, intact cuticles.

Gilbertella rot causes substantial economic losses, particularly in the post-harvest sector. It is a highly aggressive disease that can destroy large inventories of fruits during transit or storage.

The disease effectively renders the entire batch of produce unmarketable. Even a low percentage of infected fruits can result in the loss of an entire container due to the fast-spreading nature of the spores.

The necessity for labor-intensive sorting and disposal of contaminated produce adds significantly to operational costs, impacting the profitability of the entire agricultural enterprise.

Beyond the direct loss of fruit, the foul odor and physical degradation caused by the rot often contaminate surrounding healthy produce, leading to further quality degradation and market rejection.

The disease also poses a challenge to export-import logistics, as fruits that appear healthy at the point of origin may develop visible rot during transit if storage conditions are not strictly controlled.

Effective control starts with careful handling during harvest to minimize wounds, abrasions, and bruising, as healthy skin is the fruit's most effective natural defense.

Sanitation is paramount. Regularly cleaning and disinfecting storage rooms, containers, and harvesting equipment is essential to reduce the inoculum level of the fungus.

Temperature and humidity management are crucial. Maintaining optimal cool temperatures and ensuring consistent airflow helps prevent condensation and creates an unfavorable environment for fungal growth.

• Strict sorting of harvested produce to remove any symptomatic or damaged fruit.
• Implementing integrated pest management to reduce insect-related skin damage.
• Using appropriate fungicide treatments pre-harvest, if legally approved and necessary.

Biological control agents, such as specific bacterial antagonists, can be applied to the fruit surface to create a competitive barrier that prevents the fungus from colonizing the tissues.