Diseases Management in Grape Nursery

1. Diseases Management in Grape Nursery Grape seedlings are susceptible to diseases like Anthracnose, downy mildew, powdery mildew, leaf spot, leaf blight, rust which require timely care and management. Anthracnose: Small brown or grayish black lesions develop on tender shoot and young leaves. Rain and dew favor the spread of disease. These lesions develop into small holes on leaves and reduce the effective leaf area. Fungus causes cankers on the petioles and veins, and leaves become twisted and deformed.

2. Anthracnose • Control Measures • All affected plant parts showing spots, lesions and cankers should be removed and burnt or buried deep in the soil. • The disease is more problematic during October and November months, when new shoots and branches are growing, that should be protected. • Spraying of grape seedling with fungicides like Bordeaux mixture @ 0.5 % or Copper Oxychloride @ 0.15 % or Carbendazim @ 0.1 % are effective against this disease.

3. Downy Mildew • Initial symptom of disease appear as light yellow spots on the upper surface of leaves with corresponding white spots on the lower side which later turn brown. • The grape seedlings shows reduced and stunted vegetative growth & development. • Light and continuous rains, heavy dew with high humidity and low temperature favors the development of this disease. Downy Mildew on grape leaves Downy Mildew on grape leaves

4. Downy Mildew • Control : • Pruning of the vines after the second week of October helps to minimize the damage by downy mildew disease. All affected portions of the vine should be removed at the time of pruning and burn to destroyed immediately. • Bordeaux mixture (0.5%), Copper Oxychloride (0.1%), Mancozeb (0.1%), Metalaxyl (0.1%) or Fosetyl Al (0.1%) fungicides are effective against this disease. Leaves of grapes affected by downy Mildew

5. Powdery Mildew • It is the second most destructive disease in grape after downy mildew. • The disease develops under warm and dry conditions. Shade or diffused sunlight helps in the development of this disease. • The diseases is characterized by the presence of white powdery ash like coating in patches on both sides of the leaves and growing young shoots. • The affected leaves turn pale and curl up. Affected shoots remain weak and immature. Buds affected during growing season fail to sprout after pruning. Leaves Affected by Powdery Mildew Leaves Affected by Powdery Mildew

6. Powdery Mildew • Control • It can be controlled by spraying Wettable Sulphur (0.75 gm /10 litres of water) or dusting Sulphur powder (20 kg / ha) in the morning. The affected plant parts should be thoroughly coated with the dust. • Systemic fungicides like Bayleton (4 gm / 10 litre of water) or Calaxin (2 ml /10 litres of water) or Benomyl (2.5gm /10 litres of water) offer better and prolonged control of the disease. Spray should be done from November to February. Leaves Affected by Powdery Mildew

7. Bacterial Leaf Spot • The disease is more prevalent during June to August and again in February to March. Temperature range of 25-30OC and Humidity of 80-90% is favorable for the disease development. • The young growing shoots are affected initially. The symptoms appear as minute water soaked spots on the lower surface of the leaves along the main and lateral veins. Later these spots fuse to form larger patches. Leaves Affected by Leaf Spot Leaves Affected by Leaf Spot

8. Bacterial Leaf Spot • Control : • Collecting and burning infected plant parts minimizes spread of disease. • Streptocycline (500 ppm) is very effective as a prophylactic spray. Weekly sprays of copper fungicide and Bordeaux mixture given from last week of October are effective to prevent the incidence and spread of the disease. Leaves drying due to Leaf Spot Petiole Affected by Leaf Spot

9. Leaf Blight • Leaf blight disease appears in June to December months. • Small yellowish spots first appear along the leaf margins, which gradually enlarge and turn into brownish patches with concentric rings. Severe infection leads to drying and defoliation of leaves. • Control • Bordeaux mixture (0.5%), Mancozeb (0.1%),Topsin-M(0.1%),Ziram (0.25%) or Captan (0.1%) are to be sprayed alternatively at weekly intervals. Leaf Blight in Grapes Leaf Blight in Grapes

10. Rust • The weather conditions during July to December favors the development of the rust disease. • The symptoms are in the form of numerous orange colored pustules on the lower surface of the leaves. • In case of severe infection such pustules cover the entire leaf surface leading to severe defoliation. Rust in Grapes Rust in Grapes

11. Rust • Control • Rust is controlled by applying 3-4 sprays of Baycor (0.1%) or Chlorothalonil (0.1%) at fortnightly intervals during July to August and January to February. Rust in Grapes

12. Care to be Taken while Spraying • Systemic fungicides are more effective than non-systemic fungicides. However, more than 2-3 sprays of systemic fungicides should be avoided. • Continuous sprays with systemic fungicide develops resistance in pathogens and help in the resurgence of diseases like Alternaria , Botrydiplodia etc. • It is recommended to take a spray of non-systemic fungicide in between two successive sprays of systemic fungicides.