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Grape anthracnose bird's-eye spot Photo: Yulia Ilina · Pexels License · source ↗

Grape anthracnose / bird's-eye spot (Elsinoe ampelina)

Grape anthracnose, also called "bird's-eye spot", is caused by the ascomycete Elsinoe ampelina (anamorph Sphaceloma ampelinum). It is a serious early-monsoon disease in Indian grape belts, particularly damaging on the seeded Anab-e-Shahi (Grapes Anab E Shahi) cultivar of the Telangana/Andhra plateau and on neglected Thompson Seedless plots in north Karnataka and Maharashtra.

Identification and symptoms

Symptoms appear on all young green parts. On leaves, small reddish-brown spots enlarge into circular to irregular lesions with grey-white centres and dark purple-brown margins. The dead tissue at the centre often falls out, producing the diagnostic "shot-hole" or "bird's-eye" appearance. On shoots and tendrils, oval sunken cankers form with dark margins; severe infection causes shoot tip die-back and breakage. On berries, dark sunken circular lesions with a black border and pale centre - the classical "bird's-eye spot" - render fruit unmarketable; severe infection causes premature fruit drop.

Hosts and lifecycle

E. ampelina survives the dry season as sclerotia and acervuli in infected canes, mummified berries and fallen leaves. With the onset of warm humid weather and the first rains, primary infection occurs through conidia dispersed by rain-splash. Optimum temperature is 24-28 deg C with leaf wetness above 12 hours. The latent period is short (4-6 days) and repeated secondary cycles occur through the south-west monsoon.

Damage and economic impact

Anthracnose is particularly damaging when it strikes young shoots in April-June, immediately after back-pruning. Shoot dieback at this stage compromises foundation cane development and reduces the next forward-pruning yield by 20-50%. On Anab-e-Shahi the disease can produce direct fruit losses of 30% in epidemic years.

Management

ICAR-NRCG recommends an integrated programme:

  • Cultural: prune out and burn all infected canes during dormant pruning; remove mummified berries; collect and destroy fallen leaves; train the canopy for ventilation; use tolerant or resistant varieties (for example, Arka Neelamani is more tolerant than Thompson Seedless).
  • Dormant-spray: Bordeaux paste on pruning cuts and Bordeaux mixture 1% as a dormant spray after back-pruning.
  • Protectants: mancozeb 0.25% or copper oxychloride 0.3% or chlorothalonil 0.2% at 10-14 day intervals during the high-risk April-July period.
  • Systemic curatives: carbendazim 0.1%, propiconazole 0.1%, hexaconazole 0.1%, difenoconazole 0.05% - rotate to avoid resistance.
  • Sanitation: deep ploughing of orchard floor in summer to bury infected debris.

See also: Grapes Anab E Shahi, Grapes Downy Mildew Plasmopara, Grapes Powdery Mildew Uncinula, Grapes Thompson Seedless.

Sources

  1. ICAR-NRC Grapes Pune institutional portal.
  2. Anthracnose of grapevine. CABI Plantwise Knowledge Bank.