📈 Diseases of Grape — Downy Mildew, Powdery Mildew, Anthracnose

Grape (Vitis vinifera) is a commercially valuable fruit crop grown across Maharashtra, Karnataka, and other Indian states. The three most destructive fungal diseases of grapevine are downy mildew, powdery mildew, and anthracnose.

---

Downy Mildew

Causal Organism: Plasmopara viticola (Berk. & Curt.) Berl. & de Toni — an Oomycete

Symptoms

• "Oil spot" lesions — circular, yellowish, translucent patches on the upper leaf surface
• White, cottony, downy fungal growth appears on the lower surface of affected leaves
• Infected inflorescences turn brown and dry up
• Berries become soft, brown, and shrivel (known as "brown rot" of berries)

Favourable Conditions

High humidity (above 90%), moderate temperatures (20-25 degrees C), and frequent rainfall promote the disease. Sprinkler irrigation increases infection risk.

Management

• Spray Mancozeb (0.25%) or Metalaxyl + Mancozeb (Ridomil MZ, 0.2%) as a preventive measure
• Begin spraying at bud break and continue at 10-15 day intervals during the rainy season
• Ensure good canopy management with proper training and pruning to improve air circulation
• Remove and destroy fallen leaves and infected plant parts

---

Powdery Mildew

Causal Organism: Uncinula necator (Schwein.) Burrill (anamorph: Oidium tuckeri)

Symptoms

• White, powdery fungal growth on both surfaces of leaves, shoots, and berries
• Affected leaves curl upward and may turn brown at the edges
• Berries develop a greyish-white coating and crack upon enlargement
• Cracked berries are prone to secondary infections by Botrytis and other fungi

Disease Cycle

The fungus overwinters as cleistothecia on bark or as mycelium in dormant buds. Dry weather with moderate temperatures (20-27 degrees C) and shaded, humid canopy conditions favour the disease.

Management

Treatment	Dosage	Application Timing
Wettable Sulphur	0.2%	Pre-bloom through veraison
Dinocap (Karathane)	0.1%	At disease onset
Triadimefon (Bayleton)	0.1%	Alternate with contact fungicides
Hexaconazole	0.05%	During berry development

• Avoid excessive nitrogen fertilisation that promotes dense canopy growth
• Pruning and training to Y-trellis or T-trellis improves ventilation

---

Anthracnose (Bird's Eye Spot)

Causal Organism: Elsinoe ampelina (de Bary) Shear (anamorph: Sphaceloma ampelinum)

Symptoms

• Small, circular, sunken spots with dark brown to black margins and grey centres on berries — the characteristic "bird's eye" appearance
• On leaves, brown spots with irregular margins that may cause shot-hole effect
• On young shoots and tendrils, elongated dark lesions that may girdle the tissue
• Severe infection leads to defoliation and poor berry quality

Management

• Apply dormant spray of Bordeaux mixture (1%) before bud break
• Spray Carbendazim (0.1%) or Thiophanate-methyl during the growing season
• Remove and destroy infected canes during winter pruning
• Use resistant varieties where available

---

Summary Cheat Sheet

Disease	Causal Organism	Hallmark Symptom	Core Management
Downy mildew	Plasmopara viticola	Oil spots and downy growth on lower leaf surface	Metalaxyl/Mancozeb + canopy sanitation
Powdery mildew	Uncinula necator	White powdery growth on leaves and berries	Sulphur/triazoles + canopy ventilation
Anthracnose	Elsinoe ampelina	Bird's-eye sunken berry lesions	Bordeaux + systemic fungicide + pruning hygiene

References

2 sources • [1] [2]

[1]

Indian Council of Agricultural Research (ICAR)

Official

[2]

CABI Crop Protection Compendium

Website