The Bartlett pear (Pyrus communis ‘Bartlett’) is a widely recognized European pear variety. It is often classified as partially self-fertile, meaning a single tree can technically produce a limited amount of fruit. However, for a reliable, abundant harvest of high-quality fruit, cross-pollination with a different compatible variety is necessary.
The Pollination Status of Bartlett Pears
Although the Bartlett pear is described as “self-fertile,” this term can be misleading for practical fruit production. A self-fertile tree sets fruit using its own pollen, but the resulting yield is light and inconsistent. This partial self-fertility often leads to parthenocarpy, where fruit develops without successful fertilization, resulting in seedless or low-seed fruit.
For a robust fruit set, pollen transfer from a genetically distinct variety is required for fertilization. Bartlett pollen is often self-incompatible, meaning it cannot effectively fertilize the ovules of the same tree. This genetic block prevents the development of a full crop, reinforcing the need for a suitable pollination partner to maximize fruit quantity and quality.
Selecting a Compatible Pollination Partner
Selecting the correct European pear variety (Pyrus communis) is essential, with the primary factor being the matching of bloom times. The flowers of both trees must be open simultaneously for successful pollen transfer. Bartlett is a mid-season bloomer with a long bloom duration, making it an excellent pollinator for many other varieties.
Suitable partners known to bloom concurrently with Bartlett include ‘Bosc,’ ‘Comice,’ and ‘Anjou.’ These varieties provide the genetic diversity needed to overcome Bartlett’s self-incompatibility. Planting a compatible partner within 200 feet is effective, but ideal cross-pollination occurs when trees are closer, preferably under 60 feet apart. Asian pears (Pyrus pyrifolia) often have different bloom schedules than European pears, making them less reliable partners unless their specific timing is confirmed to overlap.
Ensuring Successful Fruit Set
Once compatible varieties are planted, successful fruit set depends on the efficient transfer of pollen, primarily carried out by insects. Pear blossoms are less attractive to honeybees than other fruit tree flowers due to the lower sugar concentration in their nectar. This diminished appeal requires a higher density of pollinator insects near the trees than is necessary for crops like apples.
Growers encourage pollinator activity by avoiding insecticide application during the bloom period. The presence of other bee-friendly flowers nearby helps attract and sustain local bee populations. Weather during bloom is highly influential; cool, windy, or rainy conditions significantly reduce bee activity and inhibit pollen transfer. Optimal conditions include temperatures above 60°F and calm, sunny weather to ensure maximum successful pollinator visits.