Apple Fruit Physiological Disorders

A Lecture To ToT trainees

( FFS) By

Mr. Allah Dad Khan Provincial Coordinator IPM

KPK MINFAL Pakistan

Apple: Bitter PitSYMPTOMS

BITTER PIT. APPLE, GRANNY SMITH

Small brown lesions of 2-10 mm in diameter (depending on the cultivar) develop in the flesh of the fruit. The tissue below the skin becomes dark and corky. At harvest or after a period of cold storage the skin develops depressed spots on the surface. These most often start to appear as water soaked spots on the skin near the calyx. These spots generally turn darker and become more sunken than the surrounding skin and are fully developed after one to two months in storage.

Sun Scald SYMPTOMS SUNBURN. APPLE, GRANNY SMITH

Initial symptoms are white, tan or yellowed patches found on the sun exposed side of the fruit. With severe skin damage, injured areas can turn dark brown on the tree. White, tan or yellow patches often turn brown within a few weeks in cold storage (sometimes called sunburn scald but not controlled by antioxidants, such as diphenylamine, as is storage scald). During unusually hot weather following cool or moderate conditions, and especially when accompanied by water stress, injury to the skin and flesh can occur. Injured cortex tissue is brown and firm and may become spongy and sunken. Fruit exposed to the sun after removal from the tree, either on the orchard floor or in field bins, can develop severe sunburn.

Apple: Internal Browning

SYMPTOMS INTERNAL BROWNING. APPLE, GRANNY SMITH

Brown discoloration in the flesh, firm but moist, usually originating in or near the core. Brown areas have well defined margins and may include dry cavities resulting from desiccation. Symptoms can range from a small spot of brown flesh to nearly the entire flesh being affected in severe cases. When the entire apple is affected, a margin of healthy, white flesh usually remains just below the skin. Symptoms develop early in storage and may increase in severity with extended storage time.

PHYSIOLOGICAL: Superficial Scald  

SYMPTOMS SUPERFICIAL SCALD APPEARS AS BROWN ROUGH PATCHES ON THIS GRANNY SMITH APPLE

Superficial scald is a very common postharvest disorder. The appearance and severity depends on the susceptibility of the variety with Granny Smith and Red Delicious being among the worst affected. The skin of the affected fruit turns brown in patches, especially on the shaded side, and may become rough. Only the surface of the fruit is affected, with the flesh remaining firm and of eating quality. The margins between normal and affected skin are diffuse. Browning develops rapidly once the fruit is moved from cold storage to room temperature. (Compare to Senescent scald.)

PHYSIOLOGICAL: Senescent Scald  

SYMPTOMS GOLDEN DELICIOUS FRUIT SHOWING SENESCENT SCALD AFTER COLD STORAGE.

Senescent scald appears as brown patches on the skin that may become sunken and rough with distinct margins, often ribbonlike. Unlike superficial scald, senescent scald usually appears on the sun-exposed side of the fruit and on late harvested fruit. Golden Delicious and late-harvested or over-stored fruit may be susceptible to senescent scald. Also unlike superficial scald, the interior of the fruit may have brown flesh and have internal breakdown.

PHYSIOLOGICAL: Core FushSYMPTOMS

THE PINK GRADUALLY TURNS BROWN

Core flush, a form of senescent breakdown is common in Granny Smith, Braeburn, and other apple varieties. The core area turns pink, then brown. The discoloration starts near the core and extends with wedges of brownish tissue outward. The discoloration may circle the core partially or completely. The affected tissue is moist and softer than unaffected tissue. In severe cases, it may extend just below the skin. There is no exterior symptom.

PHYSIOLOGICAL: Internal Breakdown   

SYMPTOMS Overmature and large fruit are

highly susceptible to Internal Breakdown. Internal breakdown is characterized by flesh browning and breakdown. Internal symptoms may be restricted to one side of the fruit, or involve the entire fruit. Often there is a 1/4th inch ring of healthy flesh surrounding the affected tissue. The sun-exposed side or the calyx end is more often affected, with the rest of the fruit normal. The skin of affected fruits may be normal, or dull and dark, and in later stages of the disorder, it sometimes becomes cracked

PHYSIOLOGICAL: Braeburn Browning   

SYMPTOMS SLICED BRAEBURN APPLES SHOW THE PROGRESSION OF SEVERITY OF BBD

The apple variety Braeburn is susceptible to an internal disorder called Braeburn Browning Disorder (BBD). At harvest, this disorder has the appearance of light to dark brown areas similar in nature to watercore, but occurring without pattern anywhere in the flesh. Symptoms of BBD developing in storage include tissue browning resembling the internal cavities caused by CO2 injury. However, BBD is thought to be related to late harvest

PHYSIOLOGICAL: Watercore   

SYMPTOMSA GRANNY SMITH APPLE SHOWING THE CLEAR SKIN BLOTCHES ON THE SLICE, EXPOSING THE WATER-SOAKED FLESH BENEATH.

Watercore appears as water-soaked areas of the flesh first associated with vascular bundles. In severe cases, the affected tissue may spread, covering large areas of the flesh. In these instances, watercore is externally visible by the appearance of translucent skin blotches on lighter pigmented apples, or as very dark patches on darker fruit. In mild cases, watercore will disappear (sugar reabsorbed) early on during cold storage. However, if severe enough, watercore may develop into internal breakdown (watercore breakdown).