Lambertella fruit rot of cornelian cherry

As the disease progresses, these lesions expand rapidly, eventually covering the entire surface of the fruit and causing it to soften significantly.

The texture of the infected fruit changes, becoming watery and mushy. In advanced stages, the surface of the fruit may develop a distinctive fungal mycelium or spore-bearing layer.

Eventually, the fruits undergo mummification, turning dark brown or black and becoming hard and leathery. These mummified fruits often remain attached to the branches throughout the winter.

When sliced open, the internal tissues of the infected fruit show advanced signs of decay, often accompanied by a bitter odor and a lack of firmness typical of healthy berries.

The causal agent of this disease is the fungus Lambertella corni-maris, a member of the order Helotiales, known for attacking fruits of the Cornus genus.

The fungus typically invades the fruit tissue through small wounds or natural openings in the skin, often facilitated by insect activity on the fruit surface.

Once inside, the mycelium secretes enzymes that break down the plant cell walls, allowing the fungus to colonize the interior of the drupe effectively.

The pathogen overwinters primarily within mummified fruits either on the tree or on the orchard floor, where it remains dormant until the following spring.

With the arrival of warmer, wet weather, the fungus produces apothecia on the mummified remains, which release ascospores that are dispersed by wind and rain to infect the new season's crop.

The development and spread of Lambertella fruit rot are highly dependent on prolonged periods of high humidity and moderate temperatures during the summer months.

Frequent rainfall, especially as the fruits begin to ripen, creates the ideal environmental conditions for spore germination and infection of the developing berries.

Poor orchard sanitation and overcrowding of tree canopies prevent proper air circulation, leading to moisture retention on the fruit surfaces, which promotes fungal growth.

Trees with dense, unpruned canopies are significantly more susceptible to outbreaks because they do not dry out quickly after morning dew or heavy rains.

The presence of insect pests that feed on the fruit provides the necessary entry points for the fungus, exacerbating the disease spread throughout the orchard.

The primary economic impact of this disease is substantial crop loss, as infected fruits are rendered unmarketable and unsuitable for any form of consumption or processing.

If left unmanaged, the fungus can spread rapidly throughout the orchard, causing severe localized outbreaks that can decimate the total harvest of susceptible varieties.

Infected fruits are prone to premature drop, further reducing the yield and complicating the harvesting process for the grower.

The carryover of the pathogen from year to year in mummified fruit creates a recurring cycle of infection that requires persistent effort to break.

Overall, the disease forces growers to invest more resources in disease monitoring, sanitation, and protective treatments to maintain orchard viability.

Strict orchard sanitation is the most critical management strategy, involving the thorough collection and destruction of all mummified fruits to reduce inoculum levels.

Regular pruning of the canopy is essential to improve airflow and increase sunlight penetration, which helps keep the foliage and fruits dry and less susceptible to infection.

Applying preventative fungicide treatments during the bloom and fruit-set stages can effectively protect the young drupes from initial spore infections.

Integrated pest management to control fruit-feeding insects is vital, as it prevents the physical damage that often precedes the onset of the fungal infection.

• Remove and destroy all mummified fruits.
• Prune trees to ensure good air circulation.
• Apply fungicides during critical growth stages.
• Monitor and control fruit-damaging insects.