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PHYSIOLOGICAL DISORDERS OF APPLE
BITTER PIT
—Symptoms – small brown lesions of 2-10mm in diameter. The tissue below the skin becomes dark and corky.
—Highly susceptible varieties- Granny smith, yellow Newton, Northern Spy
—Less susceptible varieties-Golden Delicious, Mc-Intosh
—Causes-due to deficiency of calcium and unbalanced nitrogen supply.

—Control –summer sprays  of  calcium chloride and calcium nitrate.
CORK SPOT
—Symptoms –a small bushed area on the skin of the fruit. Similar to bitter pit but with much deep spots in the flesh.
—Causes – both boron and calcium deficiency.
Control- combination of nitrogen and calcium spray is useful
SCALD
—Symptoms – irregular  rough brown patches of dead skin on the fruit. Symptoms develop from the previous injury which occurred during   cold storage.
—Highly susceptible varieties-  Granny Smith, Rome Beauty
—Less susceptible varieties- Gala, Fuji.
—Causes –due to hot, dry weather before harvest. High nitrogen and low calcium concentration in the fruit also causes this  disorder.
—Control –antioxidants like Ethoxyquin and Diphenylamine. Ethylene scrubbers and low oxygen storage.
WATER CORE
—Symptoms-water soaked regions in the flesh hard and glassy in appearance, water soaked areas near the core, infected fruit may smell and taste fermented.
—Susceptible varieties- Stayman, Jonathan, Suntan
—Causes- large fruit, high leaf to fruit ratio, high nitrogen and boron and low calcium, Excessive thinning.
Control- avoid delayed harvests. Matured fruit should be cut to look for water core. Donot store in CA storage for longer duration market it quickly
CORE FLUSH OR BROWN CORE
—Symptoms- slight discoloration between the seed cavities. Flesh around the core becomes rather brown.
—No sharp demarcations between healthy and affected portion of flesh.
—Causes- due to low temperature storage at 1oc to 2oc and due to increase in potassium level.
—Control- store the fruit in the storage having  1 % of oxygen.
JONATHAN SPOT
—Symptoms- depressed spots of dark brown to black colour formed on the skin.
—Causes- high level of boron. earlier maturation.
Control-spraying of 0.5 – 0.7 % of CaCl2 few weeks

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