Persimmon trees offer sweet fruit and striking autumn foliage. Originating in China, these fruits are now grown widely in temperate and subtropical climates. Growers often encounter confusion regarding when to harvest their fruit and what the yellowing of leaves or fruit signifies. Understanding the distinct characteristics of the two main persimmon types and the common causes of tree stress helps ensure a successful harvest and a healthy tree.
Decoding Persimmon Ripeness
The yellow color of a persimmon relates directly to its type, as there are two primary classifications: astringent and non-astringent. Both varieties transition from green to a rich yellow or orange as they mature, indicating they are ready to be picked, but not necessarily ready to eat. The key difference lies in the presence of soluble tannins, which cause the characteristic mouth-puckering sensation of an unripe fruit.
Astringent varieties, such as ‘Hachiya,’ contain high levels of these tannins and must be completely soft, almost jelly-like, before they are palatable. If picked while still firm, even if fully colored, the fruit will be intensely bitter. Astringent fruit is ready for harvest once the color has fully developed and it separates easily from the branch. However, it is not ready for consumption until it yields completely to a gentle squeeze, signaling the breakdown of the tannins.
Non-astringent varieties, like ‘Fuyu,’ are the exception, as they can be eaten while still firm and crisp, similar to an apple. These types have a low soluble tannin content, making the fruit sweet and ready to enjoy once it has developed its full yellow-orange color. This allows the fruit to be harvested when firm, which makes it easier to ship and store without damage.
Post-Harvest Ripening and Storage
For astringent persimmons harvested while still firm, the tannins must be removed before consumption. This is achieved by exposing the fruit to ethylene gas, a natural plant hormone that accelerates ripening and softening. A common home method involves placing the persimmons in a sealed paper bag with a high-ethylene-producing fruit, such as a ripe apple or banana, for two to three days. The enclosed space traps the gas, speeding up the chemical change that makes the tannins insoluble and undetectable.
Another method for eliminating astringency is to freeze the fruit until it is solid, which structurally alters the tannins. This method often results in a mushy texture upon thawing. Once ripened and softened, astringent persimmons have a very short shelf life due to their delicate, jam-like texture.
To maximize the storage time of firm, non-astringent fruit, keep it at temperatures near 0°C (32°F) and a high relative humidity of 90–95%. Under these conditions, non-astringent persimmons can maintain quality for up to three months. Avoid storing them alongside other ripening fruits, as persimmons are highly sensitive to ethylene, which causes excessive softening and premature spoilage. When storing, avoid a completely airtight container, as slight ventilation is needed to prevent moisture accumulation and mold growth.
Diagnosing Leaf and Tree Health Issues
When a persimmon tree’s leaves begin to yellow prematurely, the cause is often related to environmental stress or a nutritional imbalance. Improper watering is a common issue, as both drought stress and overwatering can lead to leaf discoloration and drop. Drought causes leaves to brown and drop as the tree conserves water, while excessive moisture can lead to root problems, inhibiting nutrient absorption.
Nutrient deficiencies, collectively known as chlorosis, frequently manifest as yellowing leaves in specific patterns. A lack of nitrogen often causes an overall yellowing of older leaves first, as the tree moves the limited supply to newer growth. Iron or zinc deficiency causes interveinal chlorosis, where the tissue between the leaf veins turns yellow while the veins themselves remain green. This pattern indicates a micronutrient is not being adequately transported within the plant.
Potassium deficiency often begins with yellowing and browning along the leaf margins that spreads inward. Magnesium deficiency also causes yellowing that progresses from the leaf margins toward the main veins, leaving a recognizable band of green along the veins. Addressing these issues requires a soil test to determine the exact imbalance, followed by adjusting fertilizer application or modifying the soil pH.
In addition to environmental and nutritional factors, fungal diseases can cause premature yellowing and leaf drop. Fungal leaf spot, often caused by the pathogen Pseudocercospora diospyricola, initially appears as small, dark dots on the foliage. These spots grow into irregular lesions, causing the entire leaf to turn yellow and drop from the tree. Pruning to improve air circulation and promptly removing fallen, infected leaves manage the spread of fungal issues.