JOURNAL OF MEDICINE CARE AND HEALTH REVIEW

• Fusarium oxysporum is a soil-borne fungus with a broad host range that includes many economically important and ornamental plants.
• In tomatoes, specific strains (e.g., F. oxysporum f. sp. lycopersici) cause vascular wilt, leading to symptoms such as yellowing, drooping, and plant death.
• In bananas, Fusarium oxysporum f. sp. cubense is responsible for Panama disease, a devastating vascular wilt that historically impacted the Gros Michel cultivar and now threatens Cavendish bananas.
• In chickpeas, F. oxysporum f. sp. ciceris causes Fusarium wilt, which significantly limits production in many chickpea-growing regions.
• Other leguminous crops, cotton, cucurbits, and sweet potatoes are also susceptible to various host-specific strains of Fusarium oxysporum.
• A number of ornamental plants, including tulips, carnations, and orchids, can be affected by different formae speciales of Fusarium oxysporum.
• Additional specialized forms of the pathogen target other hosts such as sugar beet (F. oxysporum f. sp. betae) and date palms, illustrating its extensive host specificity within the species complex.

Symptoms of Fusarium Wilt

• Older leaves typically begin to yellow (chlorosis) before wilting starts
• Wilting usually initiates in older foliage while younger leaves remain green until later stages
• Affected plants often become stunted with a general decline in vigor and eventual collapse
• Cross-sections of infected stems reveal vascular discoloration, showing brown or reddish streaks in the xylem
• Progressive blockage of the xylem by fungal mycelium and spores leads to impaired water and nutrient transport, intensifying the wilting symptoms
• As the disease advances, leaves may become necrotic and drop prematurely, and the overall plant development is significantly disrupted
• Etiology of Fusarium wilt
• Fusarium wilt is a vascular disease caused by soil‐borne fungi in the Fusarium oxysporum species complex, which includes both pathogenic and non‐pathogenic strains. The disease results from host-specific strains (formae speciales) that have evolved to overcome the defense mechanisms of particular plant species.
• Infection begins when fungal spores or mycelia in the soil enter plant roots through wounds or natural openings, then colonize the root cortex and invade the xylem vessels.
• Once inside the xylem, the pathogen multiplies and produces enzymes—such as cellulases and pectinases—that degrade cell walls, leading to the clogging of water and nutrient transport. Fusarium oxysporum forms different asexual spores (microconidia, macroconidia, and chlamydospores), with chlamydospores serving as durable survival structures that enable long-term persistence in soil.
• Environmental factors—including warm temperatures (typically 24°–30°C), high soil moisture, and poor drainage—are critical in enhancing the pathogen’s growth and infection efficiency. Soil properties such as pH and nutrient levels directly influence both the survival of the pathogen and the severity of disease symptoms in the host.
• The genetic variability among Fusarium isolates, often maintained by clonal reproduction and occasional horizontal gene transfer, results in a range of virulence factors that complicate disease management.
• Effective management of Fusarium wilt relies on integrated strategies such as the use of resistant cultivars, crop rotation, soil amendments, and strict sanitation to reduce pathogen inoculum in the field.

Fusarium Isolation Method

Fusarium species can be isolated on Potato Dextrose Agar (PDA) by using several techniques, including plating tissue samples, dilution, and direct isolation. Once isolated, Fusarium colonies are often characterized by their macroscopic features and color, and molecular identification may be employed for further confirmation.

Potato dextrose agar is a versatile growing medium for bacteria and fungi (yeasts and molds). This agar is used for a broad range of fungi, but there are other agars that are more selective for specific types of fungi. These agars include, but are not limited to, malt extract agar and Sabouraud agar (Figure 3)

Figure 3: Fusarium Species can be isolated on Potato Dextrose Agar

Conidiophores are short, single, lateral monophialides in the aerial mycelium, later arranged in densely branched clusters. Macroconidia are fusiform, slightly curved, pointed at the tip, mostly three-septate, basal cells pedicellate, 23-54 x 3-4.5 µm (figure 4).