1. Why Pear Growers Apply Pollen by Hand: Shelf-Trained Flowers Are Hard to Pollinate Naturally
Pears are generally grown with branches spread out like a shelf, known as "shelf training." Because the flowers bloom above the worker's head, picking buds to collect pollen is heavy labor performed while looking up [1].
Even so, pollen is necessary because pears cannot set fruit with their own pollen. To gather enough pollen for pollination, many buds must be picked. Due to a shortage of labor, the use of imported pollen is reportedly increasing [1].
The National Agriculture and Food Research Organization (NARO) lists several methods to lighten this work. In "low-tree-height joint training," where branches are arranged horizontally at a lower height, the time spent picking buds was reduced by about 40–60% compared to standard shelf training. Hand-held bud collectors have cut the time for pear bud picking by about 80%. In tests of pollination machines that use static electricity to help pollen stick to the pistil, the amount of pear pollen used was reduced by about 80%. The reduction was in the amount of pollen, not the number of fruits [1].
Just collecting and applying pollen requires this much effort. But does the weather on the day of blooming also affect the pollen?
2. How Cold Weather and Pear Variety Differences Affect Pollen Germination
After pollen lands on the pistil, it must germinate and grow a tube for pollination to proceed. A study by Tottori University (testing 130 pear varieties on agar) found that the germination rate of many varieties dropped to less than 10% at temperatures below 10°C [1].
However, three varieties—"Nara Yoshino Old Tree," "Tosa Pear," and "Imamura Natsu"—showed germination rates of over 30% even at the same low temperature. This indicates that some varieties have pollen that is strong against cold.
In recent years, it is said that blooming has been happening earlier. If flowers bloom early, they are more likely to encounter cold days, which can result in poor fruit set or growth even if pollination occurs [1].
So far, we have discussed the flowers that have bloomed. But when were these flowers prepared? It is said that preparation actually begins in the summer of the year before they bloom.
3. How Flower Buds Form in the Summer of the Year Before
In a research report from Chiba Prefecture studying the Japanese pear variety "Akizuki," it is said that flower buds begin to differentiate around late June. For this variety, the basis for the flowers that bloom in spring is created during the summer of the previous year [2]. The same report shows an example where training branches in late June to early July increased the rate of flower bud differentiation.
In Ishikawa Prefecture’s cultivation calendar (for root-zone restricted cultivation), "training" is described as pulling new shoots down at about 45 degrees from the shelf plane between mid-June and late July. The purpose is to make it easier for flower buds to form [3].
The timing of flower bud formation overlaps with the timing of training. Human intervention is not limited to applying pollen in spring. In this cultivation case, summer training was related to how flower buds formed the following spring.
Flowers are ready. Next is growing fruit from those flowers. But not all flowers are allowed to become fruit.
4. Thinning Flowers and Fruits in Stages by Hand
In Ishikawa Prefecture’s cultivation calendar, artificial pollination is done on about 2 flowers per flower cluster using tools such as bon-ten pollination wands. By limiting the number of flowers pollinated, the labor for thinning fruit later is saved [3].
The number of fruits is also adjusted in stages. In this example, preliminary thinning leaves 1 fruit per cluster by 20 days after full bloom, and final thinning leaves 5 fruits per meter of side branch by 60 days after full bloom. These numbers are an example of one cultivation method, not a rule for all pear orchards.
Chiba Prefecture’s pear growth information (July 2019) predicted that "Yosui" pears would continue to grow vigorously until around July 20, and "Hosui" until around July 30. The prefecture called for final thinning only after confirming that this peak had passed [4].
The weight of harvestable fruit is also predicted based on the diameter of fruits 80 days after full bloom. For "Yosui" in that year, the prediction was 305 g (about 10.7 oz), which was 96% of the average year, indicating smaller-than-average fruit. Working backward, the average is approximately 318 g (about 11.2 oz). This number is a prediction for that specific year and location, not a general value for pears [4].
After deciding the number of fruits and watching their size, there is something that must be protected: the bag that guards the fruit from disease.
5. Why Growers Put Bags on Young Pears to Protect Them from Disease
In Tottori Prefecture’s explanation, small bags are placed on young fruits left after thinning in May. In June, large bags are placed over them. Pruning, removing buds, pollination, thinning, bagging, and harvesting are all done by hand [5].
The purpose of the bags is to maintain the appearance of the fruit and prevent black spot disease. Black spot disease is considered the natural enemy of the "Nijusseiki" (20th Century) pear [5].
The Nijusseiki pear was introduced to Tottori Prefecture in 1904 by Kitawaki Eiji with 10 saplings [5]. However, black spot disease broke out severely, and it is said that some orchards had no harvest at all. According to local town materials, the only countermeasure at the time was Bordeaux mixture (a pesticide), and bags were made of newspaper, which did not provide sufficient protection [6].
Some people gave up, but their efforts helped make it a representative fruit of Tottori. Bagging is manual labor accumulated in the face of disease.
By the way, there was another path to fighting disease: finding pears that are resistant to it.
6. How a Disease-Free Branch Found in a Field Led to the Black Spot–Resistant Gold Nijusseiki
"Gold Nijusseiki," which is strong against black spot disease, was born from a branch found in the Gamma Field at the Ministry of Agriculture, Forestry and Fisheries’ radiation breeding station. The Gamma Field is a place where plants are grown with radiation to find branches or stocks with changed properties [7].
It is said that one branch with no disease symptoms was found in a field where pesticide spraying had been stopped. It was grafted, its resistance to disease was confirmed, and it was registered as a new variety [7].
The decades-long battle against disease expanded beyond bags and pesticides to searching for resistant branches. Human hands are involved not only in pollination, training, thinning, and bagging, but also in the variety itself.
7. What Stone Cells Tell You About a Pear's Gritty Texture
The gritty texture of pears is explained as being caused by hard cells called stone cells. A report from Yamagata University’s class shows an example of observing these cells under a microscope [8]. Since the report is about Western pears, this material alone cannot confirm if Japanese pears are the same. Still, it is a good prompt to pay attention to the fine grains that touch your tongue when eating.
Like Chiba Prefecture’s pear growth information, prefectural materials list fruit size and thinning times year by year. The figure of 305 g was the prediction for that year. How would it change if compared with other years or regions?
The numbers in this article were mostly examples from one cultivation method or one year. That leaves room for you to make your own comparisons.