The Bartlett pear (Pyrus communis), known globally as the Williams pear, is one of the most popular and widely cultivated pear varieties. Its classic flavor and versatility for both fresh eating and canning have made it a staple in orchards. Successful fruit production relies on understanding the tree’s specific reproductive needs, particularly whether it can rely on its own pollen for a reliable harvest.
The Pollination Status of Bartlett Pears
The Bartlett pear is often described as “partially self-fruitful,” a term misleading for growers seeking a substantial crop. While the tree’s own pollen can technically fertilize a small percentage of flowers, allowing for a light yield, the tree is functionally considered self-unfruitful for a heavy harvest.
This limitation is due to self-incompatibility, a biological mechanism where the tree’s stigma recognizes its own pollen as genetically identical. This prevents the pollen tube from growing down to the ovary. Without successful fertilization, most flowers will drop off the tree—a process known as “June drop”—leading to a sparse yield. Relying on this partial self-fertility is highly unreliable for a dependable fruit set.
Understanding Cross-Pollination Requirements
To overcome self-incompatibility, the Bartlett pear requires cross-pollination from a genetically distinct pear cultivar. This exchange introduces the necessary genetic diversity, allowing fertilization to proceed successfully and leading to fruit formation. Pollen transfer is primarily performed by insects, with honeybees being the most common vector.
For successful cross-pollination, two primary conditions must be met. The first is overlapping bloom times, ensuring the Bartlett flowers are receptive when the compatible partner is shedding its pollen. The second is proximity; the pollinator tree should ideally be planted within 50 to 100 feet of the Bartlett, as bees generally forage efficiently within a relatively small area.
If trees are too far apart, or if cold and wet weather limits insect activity during the bloom period, the necessary pollen transfer may not happen. This biological requirement for a genetically different partner ensures the continuation of a diverse population of pears. The result of a successful cross-pollination is a significantly higher rate of fruit retention and a much heavier crop.
Selecting Effective Pollination Partners
Home gardeners must choose a suitable pollination partner that blooms concurrently with the Bartlett tree to maximize their harvest. Since the Bartlett is a European pear (Pyrus communis), it pairs best with another European pear variety.
Compatible Varieties
Excellent pollination partners for the Bartlett include:
- The ‘Bosc’ pear
- The ‘D’Anjou’ pear
- The ‘Comice’ pear
These varieties share a similar bloom window. European pears are the most reliable option for consistent cross-pollination, though some Asian varieties may work if bloom times overlap. Growers should avoid incompatible varieties, such as the ‘Seckel’ pear.
Grafting for Limited Space
For growers with limited space, planting a second full-sized tree may not be feasible. A highly effective solution is to graft a small branch (scion) from a compatible variety, like ‘Bosc,’ directly onto the existing Bartlett tree. This method introduces the necessary genetic material onto a single root system, ensuring the required proximity and overlapping bloom without needing to plant a separate tree.