Characteristics of the fruit-bearing tree

Vigor of growth

“There are significant differences in growth vigor among the various chestnut varieties—some exhibit strong, medium, or weak growth. Growth vigor also influences the shape of the tree’s crown. Strong-growing varieties tend to develop upright crowns in their youth, before entering the fruit-bearing stage. As the tree ages, the crown shape can change considerably: a young, conical crown may transform into a round or spreading mushroom shape over time.
In more intensive orchards, professional crown shaping and pruning can greatly influence the typical trunk height and crown shape of a given variety. However, pruning should always take into account the fundamental characteristics of the variety. These considerations are especially important when dealing with a variety’s natural tendency for crown density.”

Time of budbreak

Chestnut trees bud relatively late, typically between mid-April and early May, with a variation of 20–25 days between different varieties. To avoid damage from spring frosts—especially in low-lying, frost-prone areas—it is advisable to plant later-budding types.

Blooming period

Chestnut trees bloom in late June to early July, well after the period of risk from spring frosts. The timing of flowering is important in terms of when the male and female flowers open, and how well the release of pollen coincides with the tree’s own female flowering period.

Ripening period

“The ripening period of different chestnut varieties ranges from late September to early November.
Early varieties tend to be more valuable due to higher prices at the beginning of the season. Late varieties can also be valuable because of their better storability. However, very late varieties may have uncertain ripening and can be disadvantageous; therefore, it is not advisable to plant them in low-lying areas prone to late frost.”

Ripening characteristics

There are significant differences among chestnut types in their mode of ripening. Some varieties open their burrs regularly at maturity, releasing all the fully ripened nuts at once. At the other extreme, some burrs do not open at all; instead, as ripening progresses, they fall together with the nuts inside, which then must be opened manually during harvest. Every transition between these two extremes can be found. The most advantageous are the regularly opening types, as they are the easiest to harvest. Varieties that drop with closed burrs, however, can be stored in the burrs using simple methods, and their preservation is often more favorable.

Ripening process

From an economic point of view, the ripening process is also an important characteristic — that is, how long it takes for all the fruit on a tree to reach maturity. Depending on the type, this can take between 10 and 30 days. For harvest organization, those types are more advantageous whose ripening process is completed in the shortest possible time.

Type of vegetation

An important characteristic of a tree’s vegetative type is the autumn leaf coloring and leaf fall. These traits are closely related to the variety’s growing season. There are also considerable differences among types. Early-maturing varieties show yellow leaf coloring in autumn and shed their leaves early, while late-maturing types color dark brown with the onset of autumn frosts and lose their leaves only at the beginning of winter, under the influence of stronger winds. From the perspective of proper tree maturation, early-maturing varieties with regular coloring and leaf fall are the most advantageous. However, this characteristic is strongly influenced by diseases and by the varying autumn weather conditions of individual years.

Fruiting capacity

One characteristic that influences fruiting capacity is the number of nuts per burr. Depending on the type, this can vary between 1 and 7, and there is a close correlation between fruit size and this trait. In good varieties, a burr usually contains 1–3 nuts. In burrs with 3 nuts, however, the middle fruit tends to have an unfavorable shape, as it is flattened on both sides. Another important trait affecting yield capacity is the clustering of fruits—that is, how many burrs appear on a fruiting shoot and how frequently they occur.

Fruitfulness

From the perspective of fruitfulness, the most important characteristic is what percentage of the tree’s shoots set fruit. The fruiting capacity of a variety is primarily related to this trait. Fruiting capacity also changes with age. In this respect, there is a difference between grafted cultivars and trees grown from seed. A chestnut tree grown from seed reaches fruit-bearing age only after 12–20 years. By contrast, grafted varieties are already physiologically in a fruiting state from the start; they can bear fruit as early as the year after planting, and their yield increases in parallel with the growth of the crown. A seedling chestnut producing 3 kg of nuts at the age of 8–15 years does not yet indicate that the tree has fully entered its fruit-bearing stage. In mixed stands, however, some trees may show their first fruits even earlier.