Reasons and Solutions for Yellowing Leaves of Winter Red Fruit Bonsai

Winter Red Fruit is easy to flower and has a high fruit-setting rate. Its fruits are entirely red, and the fruiting period can extend to the flowering and leafing time of the following year without dropping. It is an excellent variety for fruit-viewing bonsai and is deeply loved by the people. However, during cultivation, due to the limitation of pot capacity and other influences, the leaves often turn yellow and drop. The main reasons for the yellowing are as follows:

Yellowing Leaves Caused by Unsuitable Temperature

Winter Red Fruit likes light but cannot tolerate overly strong light. Especially in hot summer, strong direct sunlight will make the air dry and the pot soil temperature rise, causing damage to the root system, reducing enzyme activity, and causing the leaves to turn red, with dry, yellowing, and falling leaf tips. For this reason, in summer, it should be placed in a ventilated place, and water should often be sprayed around the tree body to lower the air temperature.

Yellowing Leaves Caused by Unsuitable Light

Under strong light, branches and leaves are prone to withering and yellowing, wilting, and scorched shoot tips, while under weak light, branches tend to grow leggy, fruit coloration is poor, and leaves are small and yellow and drop. Therefore, when Winter Red Fruit enters the ornamental period, its indoor placement should be close to the windowsill so that it is under bright scattered light.

Yellowing Leaves Caused by Overwatering

① Because the pot soil is watered too much, water accumulates, causing the pot 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 absorption, causing the top tender leaves to become light yellow and wilted, and the old leaves also gradually turn dark yellow. If this phenomenon is found, the plant should immediately be removed from the pot with the soil ball, placed in a cool and ventilated place, and water should often be sprayed on the leaves. Do not spray water on the roots again, so that the water evaporates as soon as possible. After the plant returns to normal, repot it.

② If the pot soil is not watered for a long time or watering does not penetrate, Winter Red Fruit will show normal color in the top center and new leaves, while the lower old leaves gradually dry and yellow upward, curl and drop, the fruit shrinks, and fruit drop is serious. When this happens, do not immediately water the pot soil thoroughly. First place it in semi-shade and spray water on the leaves first. When the leaves are no longer wilted, use the soaking method to let the pot soil slowly absorb water thoroughly. If watering is used, because the pot wall cracks are loose, water easily drains away from the gaps, resulting in watering that does not penetrate. In short, follow the principle of “do not water when dry, and water thoroughly when watering.”

③ Winter Red Fruit likes slightly acidic soil. Because northern water is on the alkaline side, long-term watering causes the pot soil to gradually become alkalized, so the plant cannot absorb iron. During cultivation, often use 1 part ferrous sulfate, 10 parts bean cake fertilizer, and 200 parts water. After decomposing, dilute it before use to change the alkalinity of the pot soil.

Yellowing Leaves Caused by Excessive Fertilization

① Too much or too concentrated fertilizer causes yellow leaves. It shows as new leaves being thick and glossy, with dark green leaf color, but the back of the leaves is wrinkled and raised, the leaves are not spread out, and the old leaves at the lower part of the plant gradually turn yellow and drop. At this time, Winter Red Fruit should be placed in shade, and the flower pot should be soaked in water to dilute the fertilizer. After two hours, remove the plant from the pot with the soil ball and dry the moisture. If necessary, remove the old leaves and remove part of the old soil to replace it with new soil.

② Winter Red Fruit grows vigorously and needs repotting once every 2 to 3 years, otherwise it is very easy to form a root pad, resulting in poor air permeability of the pot soil, difficulty for the root system to absorb water and fertilizer, thin and weak branches, long internodes, thin, tender, and yellow leaves, poor flower color, and difficulty in setting fruit. For this reason, during the dormant period, repotting and soil replacement should be carried out together with root pruning.

③ During cultivation, because undecomposed organic fertilizer is applied, the fertilizer ferments in the pot, burning or poisoning the root system. The root system turns black and rots, the leaves wilt and turn yellow, and even the whole plant dies. Therefore, organic fertilizer must be decomposed when applied. The degree of chlorosis from iron deficiency is usually relatively deep, the boundary between yellow and green is usually obvious, and brown spots generally do not appear, while the degree of chlorosis from manganese deficiency is relatively light, and brown spots or brown streaks often occur.