Pear Maturity and Harvest
Asian pears can be harvested near ripe and sold immediately for the fresh market. However, most European pears grown in the Pacific Northwest are stored and marketed over a period of time extending their availability for 6 to 8 months or longer. Long-term storage of pears can be challenging. Pears must be harvested at the right level of maturity to retain quality during storage.
Like previously noted for apples, fruit color, shape, size, soluble solids concentration (SSC), titratable acidity (TA) and firmness can be used to estimate maturity and harvest suitability. However, pear maturity indices are not as reliable or consistent as those for apples. The most consistently reliable measure is firmness which is measured with a penetrometer – the same as for apples (see apple section above).
Days after full bloom (DAFB) is a useful guide to give growers a “ball park estimate” for an approximate harvest date but this can vary from year to year. D’Anjou pears can range from 120 to 150 days; Bartletts can range from 110 to 133 days; Bosc can range from 130 to 145 days; and Asian varieties can vary from 122 to 150 days.
DA Meter: A new instrument developed by scientists at the University of Bologna, Italy, called the DA meter is used to measure the chlorophyll content in the flesh. For each variety of pear, a characteristic DA index can be developed which includes a range of values related to the maturity of the fruit. As fruit mature, the DA value decreases. DA values are related to fruit maturity and this instrument may be used for nondestructive fruit maturity determination. It can be used while fruit are still attached to the tree or also on a commercial packing line. For more information on the DA meter read the Good Fruit Grower article An easy way to test maturity.
Harvest maturity and the selection of storage regimes affect both the ripening and quality of pears during cold storage. Each variety has its own specific requirements. Note the following information regarding harvest maturity and storage regimes for common pears grown in the Pacific Northwest according to Meheriuk et al. (1988)
Bartlett pears destined for long-term controlled atmosphere (CA) storage are judged ready for harvest when their firmness reaches an average of 19.5 pounds pressure. Once this level of firmness is determined, the harvest window lasts from 4 to 7 days, depending on the weather. D’Anjou pears destined for long-term CA storage must be harvested when firmness reaches 15 pounds. Unlike Bartletts, background color, soluble solids and starch must also be taken into consideration for D’Anjous. And although variable between years, the harvest window for D’Anjous is usually around 7 to 10 days if they are to go into CA. D’Anjous are susceptible to storage scald, and friction burns to the skin. The use of plastic liners, especially in wooden bins, can reduce abrasion injury. Their quality is also affected by growing temperatures with best quality resulting when the average daily temperature is between 13.9C and 17.2C. Bosc pears for long-term CA storage are harvested when the firmness reaches 15 pounds and the appearance and finish are desirable. The harvest window for Bosc is about 7 days if they are to go into CA.
Like apples, most pears produce ethylene when mature and they also have a climacteric stage. Pears are harvested during the pre-climacteric stage when maturing has begun but the pear is not yet fully ripe. The D’Anjou pear produces very little ethylene, and is very sensitive to it, while Bartlett and Bosc varieties produce much higher levels of ethylene, in comparison to other pears. Fruit that is not conditioned this way will ripen slowly and not uniformly. The texture and flavor of nonconditioned fruit will be poor.
Pears are unique in the sense that in order to ripen, they require a pre-cooling or “conditioning” stage followed by exposure to room temperature. This is an essential part of pear maturity, as it jump-starts the internal production of ethylene, which then leads to the ripening process. Once fruits are conditioned and they are returned to room temperature, they will ripen normally. However, they can continue to be held in cold storage until a suitable marketing opportunity occurs.
For fruit harvested at the earliest maturity, Bartlett and Bosc will typically need cold storage for approximately 14 days, Comice 30 days, and D’Anjou at least 60 days. Actual times can vary somewhat from year to year. However, the traditional pre-cooling conditioning may be dramatically reduced by exposing pears to 100 parts per million of an external ethylene gas atmosphere in a sealed room at 68F for 24-48 h. For more information on harvest maturity and conditioning, read the Good Fruit Grower article Rethinking the chill requirement for pear ripening.
Asian pears are different from their European cousins. They do not require cooling to ripen and are harvested near-ripe. Generally they are not cold stored very long, but instead marketed quickly.
There are particular standards (both federal and for Washington State) required to market pears. Links for the WA state and U.S. pear standards webpages can be found below:
- Standards for summer and fall pears marketed within the state of Washington (Accessed: 1/19/17).
- United States standards for grades of summer and fall pears. (Accessed: 1/19/17).
Careful fruit handling during harvest is essential in maintaining fruit quality for the customer. Rough handling can cause bruising or skin punctures that lead to pathogen rots that can show up in storage or later in the market. This can be avoided by proper management in the field and the packing house. Dr. David Sugar, Oregon State University, discusses postharvest diseases in the 2015 video, Integrated management of postharvest diseases of pome fruits.
- Pear maturity indices used to time harvest date, P. Tvergyak, WSU Postharvest Pomology Newsletter 3(3), 1985.
- Harvest maturity and storage regimes for pears, M. Meheriuk, C. Evans, E. Talley, E. Kupferman, WSU Postharvest Pomology Newsletter 6(3): 11-15, 1988.
- Rethinking the chill requirement for pear ripening, D. Sugar, E. Mitcham, E. Kupferman Good Fruit Grower, Oct. 2009.
- Picking and storing apples and pears, Stebbins et al. Oregon State University, FS 147, 1998.
- Integrated management of postharvest diseases of pome fruits, D. Sugar, Oregon State University, 2015. (video)
- Recommendation for harvest and storage of pears, J. DeEll and K. Slingerland, Fact Sheet, Ontario Ministry of Agriculture, Food and Rural Affairs, 2012. (Accessed: 1/19/17).
- Pear production and handling manual, E. J. Mitcham and R. B. Elkins, UC-ANR Pub. 3483, 2007, (for purchase).