Beet phoma leaf spot

The first symptoms of the disease appear on the lower leaves as light brown, circular spots surrounded by a dark margin.

As the infection progresses, small black fruiting bodies called pycnidia develop in the center of these spots, which are typical signs of the fungus.

The infection can spread to the root, causing a condition known as heart rot, where the internal tissue turns black and dry.

In seedlings, the pathogen causes damping-off, which typically manifests as shriveling of the hypocotyl and often leads to plant death.

In mature beet plants or seed crops, the pathogen can cause blighting of stems and flower clusters, severely reducing seed yields.

The disease is caused by the fungus Neocamarosporium betae (formerly Phoma betae), a significant pathogen in beet cultivation.

This fungus persists in the soil on crop debris and is also commonly seed-borne, making it difficult to eradicate completely.

The pathogen can survive in various environmental conditions and remains viable on infected plant parts for several years.

Transmission occurs through rain splashes, wind currents, and mechanical activities such as tillage and cultivation practices.

It affects several crops in the Amaranthaceae family, with sugar beet and fodder beet being the primary economic targets.

High humidity and moderate temperatures between +18 and +22 degrees Celsius are the most favorable conditions for fungal growth.

Boron deficiency in the soil significantly weakens the beet's defense mechanism, making the plant highly susceptible to infection.

Short crop rotation cycles allow the accumulation of the pathogen in the soil, leading to increased disease pressure in subsequent years.

Excessive nitrogen fertilization promotes succulent leaf growth, which provides an easy entry point for the fungal spores.

Physical injuries caused by farm machinery or insect feeding facilitate the rapid spread of the mycelium throughout the root tissue.

Beet phoma leaf spot leads to significant yield losses, potentially reducing the final harvest by up to 30 percent in severe cases.

Root rot caused by this pathogen decreases sugar content and processing quality, making the beets less valuable for industrial use.

Infected roots are highly prone to secondary storage rots, which can lead to the total loss of stored batches in warehouses.

Poor seedling emergence caused by the pathogen results in thin crop stands, requiring expensive reseeding of affected fields.

The infection reduces the overall vigor of seed crops, leading to lower seed germination rates and poor initial growth.

Implementing a proper crop rotation plan with a gap of at least 3–4 years between beet crops is the most effective cultural practice.

Using certified, fungicide-treated seeds is crucial to prevent the initial introduction of the fungus into the field.

Soil testing and the application of boron-based fertilizers help maintain plant health and improve natural resistance to the fungus.

Post-harvest deep tillage helps bury crop residues, accelerating their decomposition and reducing the survival rate of the pathogen.

• Choosing disease-resistant beet varieties.
• Controlling weeds that act as alternative hosts.
• Ensuring dry and well-ventilated storage conditions for harvested crops.