Fusarium rot

Initial signs include stunted growth of the plant and yellowing of the lower leaves. Subsequently, rapid wilting of the above-ground parts is observed, which does not recover after irrigation.

Upon inspection of the root collar, characteristic dark necrotic spots are revealed. Tissues in the affected zone become soft, often turning brown or dark brown.

Cross-sections of roots and the base of the stem show clear browning of the vascular bundles. This is a direct result of vessel clogging by fungal hyphae and metabolic products.

In high humidity conditions, a loose bloom may appear on the affected areas. Its color ranges from white to pink or cream, which is typical for Fusarium infections.

If the infection affects fruits or tubers, sunken rot spots appear on them. Inside the affected tissue, dry rot often forms, leading to the mummification of the organ.

The causal agent of this disease is the microscopic fungus Fusarium nelsonii, a member of the diverse Fusarium genus. It is a soil-borne pathogen capable of surviving in plant debris and soil for long periods as chlamydospores.

The biology of this species is characterized by high adaptability to various environmental conditions. The fungal mycelium actively penetrates the vascular system of the host plant, blocking the transport of water and nutrients.

The pathogen produces various specific mycotoxins. These metabolites suppress the plant's immune system, facilitating colonization of plant tissues by the parasite.

This pathogen species is found in various agro-climatic zones. It shows high aggressiveness when attacking the root systems of both agricultural and wild plants.

The fungus is classified as a mycotoxin-producing organism, which makes it a significant risk not only for agronomy but also for food safety. Its spread is often linked to the use of contaminated seeds.

The development of the disease is closely linked to high soil moisture. The optimal temperature range for the growth of Fusarium nelsonii is between 20°C and 28°C.

Heavy, poorly aerated soils promote more rapid spread of the infection. In such soils, the root system experiences oxygen deprivation, which weakens the plant's natural defense.

Sharp temperature fluctuations and frequent stress factors trigger mass outbreaks in crops. Weakened plants become easy targets for soil-borne pathogens.

High planting density also plays a negative role. Dense plantings create a microclimate with stagnant moisture, which is ideal for spore germination.

Root damage by pests, such as nematodes or soil larvae, provides a direct entry point for the fungus. Thus, the phytosanitary condition of the soil directly influences disease incidence.

The main damage consists of mass seedling death or premature wilting of mature plants. This leads to a significant reduction in plant density in the field.

The productivity of affected plants drops sharply. The weight of fruits, seeds, or tubers decreases significantly, and their market value is lost due to poor quality.

Produce from affected areas is potentially dangerous for consumption. The presence of mycotoxins produced by the pathogen makes grain or vegetables unsuitable for use.

The accumulation of inoculum in the soil leads to the inability to grow susceptible crops in the same area for many years, necessitating costly crop rotations.

Economic losses consist of costs for fungicide applications and crop yield reduction. In years favorable for the fungus, losses can reach 30–50% of the field's potential.

The most important control method is strict adherence to crop rotation. It is not recommended to plant susceptible crops in the same field for at least 4–5 years.

The use of healthy, certified seeds is the foundation of prevention. Seed treatment with systemic fungicides helps protect seedlings during the early stages of growth.

Regular application of organic fertilizers balanced with micronutrients increases the natural resistance of plants. Special attention should be paid to phosphorus and potassium availability.

Timely destruction of plant debris after harvesting reduces the infection pool in the soil. Deep plowing facilitates faster decomposition of infected tissues.

During the growing season, if first symptoms appear, systemic fungicides should be applied. Treatments should be performed early to prevent the spread of the infection.