PHYSIOLOGICAL
DISORDERS OF APPLE
BITTER PIT
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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