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Apple: Physiological disorders

Physiological disorders in apple

P(caps)physiological disorders are abnormal conditions of fruits caused by non pathological factors. The microorganisms are never involved in physiological disorders.

Cork spot in Apple

The deficiency of calcium causes the cork spot that affects fruit quality and visual appeal. The small green dimples or depressions appear on the outer portion of the fruit flesh which turns into corky, brown and dry discoloured latter on. Mixing of calcium or limestone into soil effectively controls the cork spot.

Bitter Pit in Apple

The young bearing trees and immature fruits are more susceptible to bitter pits in which small brown lesions of 2-10 mm diameter develop in the flesh of the fruits. The tissue below the peel becomes dark and corky. The spots develop fully after 1-2 months in storage and become darker and more sunken. The spraying of calcium 45 days before harvesting and calcium dips before storage of fruits control the problem of bitter pit.

Brown Heart in Apple

The large and over mature fruits are susceptible to brown heart which increases when Co2 concentration increases above 1% in the storage. The browning of flesh near the core takes place and the symptoms develop early in storage that increases with storage period. To control the brown heart incident, the fruits should be harvested at proper maturity and stored below 1% Co2 concentration.

Scald in Apple

The inadequate ventilation in storage or in packaging boxes promotes this physiological disorder. In scald irregular brown patches of dead peel develop within 3-7 days after removal of fruits from cold storage and exposure to warm temperature but warm temperature does not cause the scald instead allow symptoms to develop from previous injury occurred during storage. The hot dry weather before harvesting, storage of immature fruits, high nitrogen and low calcium content in the fruits favour the scald development. The problem can be reduced by harvesting the fruits at proper maturity and maintaining ventilation in the cold storage. Application of antioxidant Diphenylamine (DPA) just after harvesting controls the scald problem. 

Apple: Diseases (link)

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