Diseases of apple

a) Apple scab:

• Scab is caused by a fungus that infects both leaves and fruit.
• Scabby fruit are often unfit for eating.
• Infected leaves have olive green to brown spots.
• Leaves with many leaf spots turn yellow and fall off early.
• Leaf loss weakens the tree when it occurs many years in a row.
• Planting disease resistant varieties is the best way to manage scab.
• Fungicides can be used to manage apple scab. Proper timing of sprays is needed for fungicides to control disease.

b) Pink disease:

• At first round, pink lesions will appear on the bark which progressively grows bigger and cause crack.
• Later on, thin sheets of bark will become dry and peel off and killing the whole branch.
• Apply Bordeaux paste in the lesions, prune affected parts and burn it to control the disease.

c) Powdery Mildew:

• On infection, whitish powdery patches on twigs and both sides of leaves are seen.
• Infected fruits show signs of rusetting.
• Spraying with Wettable sulphur powder @300 gm/100 liter of water or carbendazim @50 gm/ 100 liters of water thrice during flowering , at bud formation and petal fall stage can control this disease.

d) Collar rot:

• Phytophthora cactorum causes seedling damping off, a reduced root system and black discolouration of the roots.
• On the foot, dark brown lesions with sharp borders occur.
• Above the graft and on leaves, dark brown, irregular lesions occur.
• Disease can be controlled by removing the bark and applying Copper oxychloride paint.
• Drenching 30 cm radius area around the trunk with mancozeb (0.3-0.4%), or copper oxychloride (0.5%) or Metalaxyl (0.3%) can control this disease.