Grape anthracnose

Sphaceloma necator, which represents the anamorph state of Elsinoë ampelina, is a significant fungal pathogen responsible for anthracnose of grapevines. Taxonomically, it belongs to the Ascomycota division. This fungus acts as an obligate parasite that specifically infects Vitis species, causing severe damage to vegetative and reproductive parts of the plant.

The disease affects leaves, stems, flowers, and berries. Typical symptoms include irregular brown spots with dark margins on leaves, which often drop out to create a shot-hole appearance. On shoots, the fungus creates sunken, dark-colored lesions that can girdle the stem, while berries display the characteristic 'bird's eye' spots, often leading to fruit mummification.

The biological cycle of the fungus centers on the production of conidia within acervuli. The pathogen overwinters primarily as mycelium or sclerotia within diseased vine canes or mummified berries. When temperatures rise in the spring and moisture is abundant, these structures release spores that initiate primary infections during the growing season.

Environmental conditions play a critical role in the dissemination of the disease. High humidity, frequent rainfall, and moderate temperatures between 20°C and 25°C are optimal for spore germination and infection. Conversely, dry and hot conditions can slow down the progression of the pathogen, making spring the most dangerous time for new outbreaks.

Effective management and control are essential to prevent economic loss. Key strategies include:

• Rigorous sanitation, involving the removal and destruction of infected canes.
• Improving canopy ventilation through proper pruning and trellising to reduce humidity.
• Application of protective fungicides, including copper-based products and systemic chemistry during the early stages of bud break and leaf development.