Black foot of grapevine

The most distinct symptoms include reduced vegetative growth, shortened internodes, and yellowing (chlorosis) of the leaves during the active growing season.

Affected roots exhibit dark to black necrotic lesions that can girdle the rootstock and lead to total root system degradation over time.

Cross-sectioning of the trunk base or roots reveals dark brown to black staining in the wood, indicating the obstruction of the vascular system by fungal mycelium.

Young plants often show signs of overall stunted development, appearing brittle and weak compared to healthy vines in the same block.

In severe cases, the entire root system may rot away, causing the plant to collapse or be easily uprooted from the soil.

The causative agent of black foot disease is the soil-borne pathogenic fungus Campylocarpon fasciculare (teleomorph Cylindrocladiella parva), which is a major component of the Young Vine Decline complex.

This microscopic pathogen is capable of surviving in the soil for extended periods by forming dormant structures, making it highly resistant to harsh environmental conditions.

The fungus primarily attacks the root system, entering through natural openings, mechanical wounds, or grafting points, and gradually colonizes the plant's vascular tissues.

Infection often initiates in commercial nurseries where propagation conditions, if not strictly managed, can promote the spread of the fungus among young vines.

The disease is a major concern for viticulturists worldwide as it leads to progressive decline and poor establishment of newly planted vineyards.

The development of Campylocarpon fasciculare is heavily favored by waterlogged or poorly drained soils which reduce root oxygen levels and weaken the vine.

High moisture levels in nurseries, particularly in potting media, significantly increase the risk of fungal spread during the propagation process.

Moderate temperatures allow the pathogen to grow actively and infect new root tissue, making early spring and late autumn critical periods for infection.

Poor soil structure and compacted soils prevent proper root aeration, which is essential for the vine to resist the encroachment of root-rotting fungi.

The movement of infected nursery stock is the primary pathway for introducing the pathogen into new, previously clean vineyard sites.

Black foot disease causes significant economic loss by leading to the death of young vines within the first few years of establishment.

The disease creates uneven vineyards with large gaps, which interferes with mechanized maintenance and reduces the overall yield potential of the plot.

Replacement of dead vines is a costly and time-consuming process that requires re-preparation of the soil and further expenditure on new plant material.

Once established in the soil, the pathogen is extremely difficult to eradicate, potentially excluding the site from replanting for several years.

Secondary infections by other root pathogens are common, as the weakened root system of a black foot-affected vine becomes highly susceptible to further decay.

Management begins with the use of high-quality, pathogen-free nursery stock, which should be sourced from reliable suppliers and vetted for infection.

Vineyard site selection and preparation are critical, ensuring excellent soil drainage to prevent the anaerobic conditions that favor fungal development.

Cultural practices such as deep ripping, proper irrigation management, and using resistant rootstocks can mitigate the impact of the disease.

• Rigorous inspection of nursery vines before planting.
• Improving soil drainage through tiling or raised beds.
• Removal and destruction of infected vines with their surrounding soil.
• Application of bio-control agents to enhance root health.

Sanitation is paramount; equipment used in infested areas should be disinfected before moving to clean blocks to prevent the spread of soil-borne inoculum.