Acremonium neck rot

The primary symptom is the appearance of dark, sometimes oily-looking lesions localized at the stem end or the "neck" of the fruit. As the infection progresses, the lesion expands in size and darkens.

Under high humidity, a characteristic white to cream-colored mold or mycelial growth may develop on the surface of the affected area, indicating active sporulation of the fungus.

The internal tissue beneath the rot becomes soft, watery, and disorganized. The pulp may develop an unpleasant odor as the fungus breaks down the cellular structure of the fruit.

In crops like mangoes and bananas, the rot spreads from the pedicel down towards the main body of the fruit. This makes the fruit commercially unviable and prone to secondary infections.

As the disease advances, the entire fruit may lose its structural integrity, turning into a decaying mass, even if the exterior skin appears relatively intact during the initial stages of the infection.

The causative agent of this disease is a fungus from the Acremonium genus (most commonly Acremonium strictum). It acts as a facultative parasite that primarily attacks fruits after harvest during the storage or transport stage.

The disease is classified as a postharvest fruit rot. The fungus typically invades plant tissues through natural openings or mechanical wounds caused by handling, shipping, or harvesting activities.

This pathogen produces enzymes that degrade plant cell walls, leading to tissue softening and decay. Its ability to thrive on sugar-rich environments makes it particularly hazardous for tropical fruits.

Microscopic analysis reveals thin, septate hyphae and characteristic phialides. The fungus is capable of surviving in the soil and on crop debris, spreading easily via wind or water splashes before reaching the fruit.

Acremonium rot often appears in association with other fungi, such as Colletotrichum species (anthracnose), making field diagnosis complex and often requiring specialized laboratory identification.

High relative humidity (above 85%) is the most critical environmental factor promoting the rapid growth and sporulation of Acremonium fungi on fruit surfaces.

The disease develops most aggressively within an optimal temperature range of +22°C to +28°C. These temperatures are standard for the postharvest ripening process of tropical produce.

Mechanical injuries such as cuts, bruises, or stem breakage during harvest provide entry points for fungal spores, allowing the pathogen to penetrate deep into the fruit flesh quickly.

Poor ventilation during storage and transport creates microclimates with stagnant, humid air, which significantly accelerates the spread of infection between individual fruits in a container.

Agrotechnical management, including excessive nitrogen application before harvest, can increase tissue susceptibility, making the fruits more prone to rapid decay post-harvest.

The major impact of Acremonium neck rot is significant postharvest loss during shipment, leading to high economic consequences for international fruit trade and local markets.

Infected fruits lose their market value entirely due to unsightly lesions and accelerated spoilage, often leading to the rejection of entire shipments upon arrival.

The pathogen is highly contagious within storage environments. A single infected fruit can quickly trigger a chain reaction, spreading the fungus to healthy neighboring fruits.

Contaminated produce cannot be used for food processing due to potential metabolic byproducts produced by the fungus, which may negatively affect safety and flavor profiles.

Logistics companies and retailers face increased labor costs associated with sorting and disposing of infected produce to prevent the further spread of the disease.

Strict sanitation protocols in packing houses and storage facilities are essential. Regularly cleaning and disinfecting surfaces can significantly reduce the initial inoculum.

Postharvest treatment with approved fungicides can protect the fruit surface from initial fungal penetration. It is crucial to follow regulatory guidelines for chemical residue levels.

Maintaining a controlled cold chain, including precise temperature and humidity monitoring, is vital to inhibit fungal growth during the transportation of tropical fruits.

Careful grading and sorting of fruit allow for the removal of bruised or damaged items before they are packed, minimizing the risk of spreading the infection.

• Implementing proper cooling after harvesting.
• Using biocontrol agents to suppress fungal growth.
• Ensuring adequate ventilation in transit containers.
• Staff training on careful fruit handling techniques.