What to do when the leaves of a winter red fruit bonsai turn yellow? Causes and solutions

The winter red fruit flowers easily and has a high fruit-setting rate, with fruit that is entirely red; the fruiting period can extend to the next year when it flowers and grows leaves without the fruit dropping, making it an excellent variety for fruit-viewing bonsai, deeply loved by the people. However, during cultivation, due to the restriction of pot capacity and other influences, the leaves often become chlorotic and drop. The main causes of this yellowing are as follows:

Leaf yellowing caused by unsuitable temperature

The winter red fruit likes light but cannot tolerate excessive intensity; especially in the hot summer, strong direct sunlight will dry the air and raise the temperature of the potting soil, damaging the root system, reducing enzyme activity, causing the leaves to turn red, and the leaf tips to dry up, become chlorotic and fall. Therefore, in summer, it should be placed in a ventilated spot, and water should frequently be sprayed around the tree to lower the air temperature.

Leaf yellowing caused by unsuitable light

Strong light exposure easily causes branches and leaves to wither and yellow, wilt, and shoot tips to scorch, while weak light easily leads to leggy branches, poor fruit coloring, and small leaves that turn yellow and drop. Therefore, when the winter red fruit enters its ornamental period, its indoor placement should be near a windowsill, so that it is under bright scattered light.

Leaf yellowing caused by overwatering

① When the potting soil is watered too much, water accumulates, causing the potting soil to lack oxygen; some fibrous roots suffocate and rot, losing the ability to absorb water and nutrients. At the same time, respiration increases bicarbonate ions, which in turn affects iron uptake, causing the top tender leaves to become pale yellow and wilt, while the old leaves also gradually turn dull yellow. If this phenomenon is found, the plant should immediately be removed from the pot with its soil ball, placed in a cool, ventilated spot, and water sprayed frequently on the leaves; do not spray water on the roots again, so that the moisture evaporates as quickly as possible. Once the plant returns to normal, repot it.

② If the potting soil is not watered for a long time or watering does not penetrate, the winter red fruit will show normal color in the terminal buds and new leaves, while the lower old leaves gradually dry and yellow upward, curl and drop, and the fruit shrivels, with severe fruit drop. When this happens, do not immediately water the potting soil thoroughly; first place it in a semi-shaded spot, spray water on the leaves first, and once the leaves are no longer wilted, use the soaking method to let the potting soil slowly become thoroughly moistened. If watering is used, because the pot wall cracks are loose, water easily drains out through the gaps, resulting in incomplete watering. In short, follow the principle of “do not water if dry, water thoroughly when watering”.

③ The winter red fruit likes slightly acidic soil. Because water in the north tends to be alkaline, long-term watering causes the potting soil to gradually become alkaline, so the plant cannot absorb iron. During cultivation, often use 1 part ferrous sulfate, 10 parts soybean cake fertilizer, and add 200 parts water; after decomposing, dilute and use it to change the alkalinity of the potting soil.

Leaf yellowing caused by excessive fertilization

① Yellow leaves caused by too much or too concentrated fertilizer. It shows as new leaves that are thick and glossy, with dark green color, but the underside of the leaves is wrinkled and raised, the leaves do not spread out, and the lower old leaves of the plant gradually turn yellow and drop. At this point, place the winter red fruit in a shaded spot, soak the flowerpot in water to dilute the fertilizer, and after two hours, remove the plant from the pot with its soil ball and let the moisture dry. If necessary, remove the old leaves and pick out part of the old soil to replace it with new soil.

② The winter red fruit grows vigorously and needs repotting once every 2 to 3 years; otherwise, it easily forms a root mat, causing poor air permeability in the potting soil, difficulty for the roots to absorb water and fertilizer, thin and weak branches, long internodes, thin, tender, yellow leaves, poor flower color, and difficulty setting fruit. Therefore, during the dormant period, repot and change the soil while trimming the roots.

③ During cultivation, because undecomposed organic fertilizer is applied, the fertilizer ferments inside the pot, burning or poisoning the root system; the roots turn black and rot, the leaves wilt and turn yellow, and even the whole plant dies. Therefore, organic fertilizer must be fully decomposed when applied. The degree of chlorosis from iron deficiency is usually deeper, with the boundary between yellow and green often obvious, and generally no brown spots appear, while the degree of chlorosis from manganese deficiency is lighter, and brown spots or brown streaks often occur.