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Diseases & Disorders of Pear

Postharvest diseases in Pears are generally caused by fungal pathogens that can infect fruit before, during, and after harvest.  Understanding when infection occurs is an essential step for developing and implementing control measures to reduce storage losses due to decay. Fruit that are infected in the orchard will not show symptoms until later in storage.  Dead bark, twigs, and cankers on trees may contain fungal pathogens like Potebniamyces pyri, which causes Phacidiopycnis rot. Growers must begin disease control procedures in the orchard for postharvest diseases of pears that cause decay in storage.  Orchard sanitation and pre-harvest fungicide treatments are important steps in disease control.  Some decay causing organisms infect wounds that occur during the harvest and postharvest handling processes.  Limb rubs, stem punctures and bruises are entryways for fungal spores such as Blue mold, caused by Penicillium spp., mainly P. expansum, and Gray Mold caused by Botrytis cinerea.  Accurate identification of postharvest diseases is the first step in applying appropriate actions for control. See the Postharvest diseases of apples and pears guide here, and the apple postharvest quick identification guide for more information on these diseases.

Harvest maturity is a critical variable in helping prevent storage decay.  Pears harvested on the immature side will scrape easily on the packing line, introducing wounds, which are sites for infection, and fruit harvested late in the maturity range has reduced storage life, and is more susceptible to postharvest diseases. Careful handling of pears at harvest, and preventing wounds is crucial. Packinghouse sanitation is also imperative in the disease control process.  Winter pears such as d’Anjou, are usually packed shortly after harvest in cardboard boxes, and can be stored in CA storage for up to 9 months in Washington State. Decay on packed fruits in the boxes is a major concern for growers and warehouse managers.

Scientists at WSU are working with growers and packinghouse personnel to find better ways to control decay in postharvest fruit.  For information on pears, and postharvest diseases, visit WSU’s postharvest information network.

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