Fusarium rot (Fusarium nelsonii)

Pathogen and disease type. The pathogen Fusarium nelsonii is a soil-borne fungus belonging to the Ascomycota division. It causes severe vascular and root diseases in plants, often referred to as Fusarium rot or Fusarium wilt. This fungus is known for its ability to produce various mycotoxins, which can contaminate agricultural products, making them unsuitable for animal or human consumption and leading to economic losses.

Host crops. Fusarium nelsonii has a wide host range, infecting various vital crops. It is frequently isolated from cereals, including wheat and barley, as well as corn (maize) and sorghum. Vegetable crops and certain ornamental plants can also act as hosts. The pathogen often acts as an opportunistic parasite, attacking plants that have been stressed by poor environmental conditions or pest damage.

Symptoms and signs. The disease manifests as stunted growth, chlorosis, and gradual wilting of the plant starting from the lower leaves. If the stem is cross-sectioned, brown discoloration of the vascular tissues is often visible, indicating internal colonization by the fungus. Under humid conditions, a visible mycelial mat, often white or pinkish in color, may develop on the roots or at the base of the stem.

Development and spread. Optimal conditions for the growth of Fusarium nelsonii include high soil moisture levels and moderate temperatures (approximately 20–28°C). The fungus survives in the soil, on crop debris, and can be seed-borne. Spread occurs through contaminated irrigation water, movement of soil by farm machinery, wind-dispersed spores, and the sowing of infected seeds, which is a primary pathway for long-distance transport.

Harmfulness and protection measures. The disease significantly reduces yield potential by decreasing seedling emergence and causing premature death of adult plants. Integrated control strategies include:

• Sourcing clean, pathogen-free seeds for planting.
• Using systemic fungicide seed treatments to prevent early infection.
• Practicing crop rotation to break the pathogen's life cycle.
• Implementing good soil drainage and tillage to minimize fungal reservoirs.
• Balancing fertilization to avoid excessive nitrogen, which can make plants more susceptible.