Scab

Scab
Scab :
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C. O.: Venturia inaqulis

Symptoms:

• Olive colored irregular spots appear on sepals and young leaves of the flower buds.
• Upper surface of older leaves lesions become olive green to grey with a velvety surface. Later lesions become metallic black in colour.
• Small scab spots appear on twigs and blossoms.
• Infected fruit develop circular scab lesions; margin of the lesion becomes cracked, premature drop of the fruit.

Favourable conditions:

• Cool, wet periods of spring, early summer favours the development of the disease.
• Ascospores germinate at a temperature of 6 to 260C.

Management:

• Collection and destruction of infected fallen leaves.
• Spray 5 % urea is recommended for hastening the decomposition of the leaf.
• Give post symptom spray with Carbendazim 0.025% 0r mancozeb 0.20% or captan 0.20% or benlate 0.10%which have eradicant and antisporulant activity.
• Resistant varieties: Prima, Priscilla, Sir Prize


Fire blight
Fire blight.:
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C. O.: Erwinia amylovora
First Report plant diseases caused Bacteria by T. J. Burrill in 1878.

Symptoms :

• Symptoms developed on leaf, twigs, flowers and fruits becomes brownish black.
• Blackening progress leaves curl and shrivels.
• Terminal twigs are infected directly and wilt from tip downward.
• Infected small immature fruit became water soaked, turn brown, shrivel and turn black.

Favorable condition :

• Warm and humid weather
• Insects, honey bees

Management:

• Pruning of infected branches should be done 30 cm below from the point of infection during summer reduce the inoculum.
• Spraying with copper oxychloride 0.20% or Bordeaux mixture (0.6%) in combination with streptomycin sulphate (250ppm) is effective.


Powdery mildew
Powdery mildew:
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C.O.: Podosphaera leucotricha

Symptoms :

• Disease appears after the buds develop into new leaves and shoots.
• Early symptoms on leaves consists of small white patches and grey powdery masses on the under surface which will later spread to both surfaces.
• Margin is curled, leaves turn brown from tip to down ward.
• Partial defoliations.
• Fruit buds suffer more damage than vegetative buds.
• Infected fruits remain small, deformed and trend to develop a roughened surface.
• In nursery plants, disease prevents formulation of wood in the stem

Management :

• Pruning of infected twigs with leaf and burning it.
• Sprays of dinocap (0•025 %) or carbendazim 0.05% or hexaconazole 0.005%.
• Maharaja chanth and Golden Chinese found resistant to it.