WSU Tree Fruit Research & Extension Center

Tree Fruit Market Diseases

Sunday, November 19, 2017

WSU-TFREC/Postharvest Information Network/Tree Fruit Market Diseases/pearpithy



Pithy brown core, also known as brown core, is a disorder affecting Anjou, Bartlett, and Bosc pears stored in sealed polyethylene box liners. It is characterized by pithy, brown discolored areas in the core region of the fruits. It may be restricted to brown flecks between the carpels, but it may also encompass the entire core and extend into the surrounding flesh (see photos). In some instances the tissues collapse to produce cavities. Affected tissues are dry and pithy, in contrast to the soft, watery texture found in core breakdown.

The disorder is associated with high concentrations of carbon dioxide in the atmospheres within sealed box liners, and is considered to be a form of carbon dioxide injury. It is aggravated by a combination of low oxygen and high carbon dioxide levels in the liner. Advanced maturity at harvest, delayed cold storage, and slow cooling of the fruits in storage also contribute to the severity of the disorder. Susceptibility to carbon dioxide injury varies from year to year and is influenced by weather conditions. Fruits grown during seasons with relatively low mean temperatures are more susceptible to pithy brown core than fruits grown during relatively warm seasons.

Commercial control of the disease has been attained by using perforated polyethylene box liners that maintain desired levels of oxygen and carbon dioxide during the storage period. Experimentally, pads containing hydrated lime have kept the concentration of carbon dioxide below the injurious level in sealed liners.

Pear pithy brown core (carbon dioxide injury)
Pear pithy brown core (carbon dioxide injury)

Pear pithy brown core (carbon dioxide injury)
Pear pithy brown core (carbon dioxide injury)

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