Brown rot of strawberry

The initial symptoms appear as small, circular, brown spots on the developing or mature strawberry fruits. These lesions expand rapidly under conducive conditions.

Affected tissues become soft and watery, eventually turning into a uniform brown mass. During high humidity, you may observe the formation of fungal sporulation structures on the surface of these spots.

The fruit often becomes deformed, shriveled, and completely inedible. In advanced stages, the entire berry may be consumed by the fungus, leaving only a withered structure.

Flower stalks can also be attacked, leading to necrotic lesions that cause the stems to bend and eventually die, preventing fruit development.

• Brown circular lesions on fruit.
• Soft and watery rot of the berries.
• Presence of light-colored spore masses.
• Withered and necrotic flower stalks.
• Premature fruit drop and deformation.

The causal agent of brown rot in strawberries is the fungus Discohainesia oen, also known as Hainesia lythri. This pathogen belongs to the Ascomycota division and is a serious threat to berry crops.

The fungus overwinters in plant debris and soil, serving as a primary inoculum source. Under favorable conditions, it produces spores that infect healthy tissues of the strawberry plant.

It predominantly infects the fruit but can also colonize stalks and leaves. The pathogen secretes cell-wall-degrading enzymes that cause tissue softening and rapid disintegration.

Dissemination occurs primarily via splashing rain and wind, which transport conidia from infected fruit to healthy ones within the planting area.

Knowledge of the Discohainesia oen lifecycle is essential for farmers, as the pathogen remains active throughout the flowering and fruiting stages of the strawberry crop.

Wet and rainy weather is the primary driver for brown rot development. High humidity levels provide the necessary environment for the pathogen to thrive and infect.

Temperatures ranging from 15°C to 22°C are ideal for the rapid germination of conidia and the subsequent colonization of the host plant tissues by Discohainesia oen.

Poor air circulation, often caused by overly dense planting or lack of pruning, keeps the foliage and fruit wet for longer periods, significantly increasing the infection risk.

Overhead irrigation is particularly risky as it ensures prolonged surface wetness on fruits, which facilitates the penetration of the fungus into the plant tissues.

Presence of organic debris, such as fallen leaves or old rotting berries, acts as a reservoir for the pathogen, sustaining the disease cycle from one season to the next.

The economic impact of brown rot is significant due to the complete loss of marketable yield. Even slightly affected berries are rejected by consumers due to rapid spoilage.

The disease can destroy entire harvests during rainy periods, leading to substantial financial losses for strawberry growers and commercial farms.

Prolonged infection weakens the strawberry plants, reducing their vitality and overall yields in subsequent growth cycles if the inoculum is not managed properly.

Post-harvest losses are also high, as berries infected in the field continue to rot during transit and storage, contaminating surrounding healthy fruit.

Managing the infection requires significant labor and financial resources, including the removal of infected material and the application of protective fungicide sprays.

Effective management begins with sanitation. Regularly removing and disposing of infected berries and plant debris is vital to decrease the pathogen load on the field.

Applying mulch, such as clean straw or plastic mulch, prevents the fruit from touching the soil, creating a physical barrier against soil-borne spores of the pathogen.

Good cultural practices, such as proper plant spacing and weed management, improve airflow and allow the plants to dry quickly after rain or irrigation.

Switching from overhead to drip irrigation is highly recommended to keep the fruit surface dry and reduce the likelihood of fungal infection.

In cases where environmental conditions favor disease outbreak, preventative fungicide applications during flowering are necessary to protect the developing fruit.