Introduction to Grape Cultivation
- Grapes (Vitis vinifera) are a major fruit crop grown globally for fresh consumption, raisins, and wine.
- Optimal growth requires balanced nutrition, pest and disease management, and proper cultural practices.
- Understanding disorders and their management is crucial for high yield and quality.
Nutrient Disorders in Grapes
- Common deficiencies: Nitrogen, Potassium, Magnesium, Zinc, Boron, Iron.
- Symptoms include chlorosis, poor fruit set, stunted growth, and leaf necrosis.
- Soil and leaf analysis help diagnose nutrient disorders.
Corrective Measures for Nutrient Disorders
- Apply recommended fertilizers based on soil and tissue analysis.
- Use foliar sprays for micronutrient deficiencies (e.g., ZnSO4 for zinc, Fe-EDTA for iron).
- Incorporate organic manures and green manures to improve soil health.
- Maintain proper irrigation to aid nutrient uptake.
Growth Regulators in Grapes
- Gibberellic acid (GA3) used to increase berry size and improve cluster looseness.
- Apply 25 ppm GA3 at calyptra fall and pepper stages for seedless varieties.
- Potassium chloride (0.2%) sprayed at 20 and 40 days after berry set for uniform ripening.
Physiological Disorders in Grapes
- Berry cracking: Caused by irregular watering or boron deficiency.
- Uneven ripening: Linked to potassium deficiency or hormonal imbalance.
- Poor fruit set: Often due to zinc or boron deficiency.
Major Pests of Grapes and Management
Nematodes- Apply carbofuran 60 g/vine one week before pruning; irrigate well.
- Use neem cake 200 g/vine and Pseudomonas fluorescens for biocontrol.
Flea Beetles- Spray phosalone 2 ml/l after pruning; repeat 2–3 times as needed.
Thrips- Spray dimethoate 2 ml/l for control.
Mealy Bug- Spray monocrotophos 2 ml/l; use sticky bands and natural predators for IPM.
Major Diseases of Grapes and Management
Powdery Mildew- Caused by Uncinula necator.
- Symptoms: White powdery growth on leaves, shoots, and berries.
- Management: Sulphur dusting @ 6–12 kg/ha; use resistant varieties.
Downy Mildew- Caused by Plasmopara viticola.
- Symptoms: Yellowish oil spots on leaves, white downy growth on lower surface.
- Management: Spray 1% Bordeaux mixture; ensure good air circulation.
Harvesting, Yield, and Storage of Grapes
- Harvest only after full ripening for best quality.
- Heat requirement: 2900–3600 degree days for most varieties.
- Average yields: Seedless – 15 t/ha/yr; Muscat – 30 t/ha/yr; Pachadraksha – 40 t/ha/yr; Anab-e-Shahi/Arka hybrids – 20 t/ha/yr.
- Room temperature storage: Up to 7 days; cold storage (-2 to -1.5°C): 40–45 days.
Raisin Production from Grapes
- Raisins are a major by-product in grape-growing regions.
- Grapes with 17° Brix and above are suitable; 20–23° Brix is standard for high-quality raisins.
- Proper drying and storage are essential to prevent spoilage.