(1) Excessive watering leads to high soil moisture for a long time, which leads to lack of oxygen in the soil, which prevents some roots from breathing normally and absorbing water and nutrients, leading to yellowing and falling off of leaves. After injury, the young leaves first turn pale yellow, and then the old leaves gradually turn yellow. Water should be controlled immediately, fertilization should be suspended, and soil should be loosened frequently to make the soil well ventilated.

(2) Drought dehydration. It affects the absorption of nutrients and easily leads to dull drooping of leaves. First, the lower old leaves are aging and gradually wither and fall off from bottom to top. At this time, it is necessary to water a little, spray some water, let it gradually recover, and then turn to normal watering.

(3) Long-term fertilization. Long-term non-application of ammonia fertilizer or changing pots and soil, the soil lacks nutrients such as nitrogen, which leads to sparse branches and leaves, thinning and yellowing. It is necessary to pour pots in time, replace them with new loose and fertile culture soil, and gradually increase the application of dilute decomposed liquid fertilizer or Ribelli bird's nest microbial inoculum.

(4) Overfertilization. Excessive fertilization will result in uneven thickness of new leaves and brown loss of old leaves.

(5) hot and high temperature. Direct sunlight at high temperature is likely to cause the tips and edges of young leaves to scorch, or the leaves will fall off and turn yellow.