Causes and preventive measures of defoliation of banyan bonsai in the north

Banyan (FicusmicrocarpaL.) is an evergreen ornamental plant of Moraceae, which is generally cultivated in bonsai in the north. The banyan tree has bright green leaves, vigorous branches and various postures, especially the spiral air roots, giving people a simple, desolate and generous feeling, is a good bonsai plant. However, the banyan bonsai is always defoliated in the north, which seriously affects the ornamental effect. The author has explored this for many years, analyzed the reasons, and summed up the prevention methods.

1 the cause of falling leaves

The leaves of banyan bonsai in the north can be divided into two situations.

1.1 the fallen leaves of the healthy banyan trees just purchased are mainly caused by sudden changes in the growth environment. The rapid changes of temperature, humidity and light, especially the environmental humidity, will directly lead to a large number of leaves of banyan trees shedding in a short time.

1.2 factors such as gradual weakening of tree potential, lack of nutrition, lack of soil fertilizer, alkalization or diseases and insect pests should be considered when bonsai leaves are cultivated for a long time.

2 measures to prevent falling leaves

2.1 to buy healthy plants with outstretched leaves, bright green color, and free from diseases and insect pests, and preferably long-term pots. This can be judged from whether there are new excavations on the surface of the basin soil. The cultivated soil should be loose, fertile and breathable.

2.2 to strengthen the management after repurchase, attention should be paid to imitating the previous growth environment, especially at the beginning, attention should be paid to improving the air humidity around the banyan plant so that it can gradually adapt to the new environment.

2.3 Daily management should be placed in a brighter room, no less than 5 ℃ in winter and no more than 35 ℃ in summer, and pay attention to ventilation and often spray water to the leaves. After Grain Rain, a period of time before Cold Dew can also be placed outdoors, summer should be slightly shaded. Be careful to stay away from heat sources in dry rooms, especially at low temperatures.

2.4 Fertilizer pay attention to the frequent application of thin fertilizer, more thin fermented cake fertilizer or alum fertilizer water. 0.2% urea water or 0.2% potassium dihydrogen phosphate solution can also be sprayed irregularly, but thick fertilizer and raw fertilizer must be avoided.

2.5 active control of leaf diseases and insect pests can lead to defoliation, but root diseases and insect pests can also cause defoliation. Attention should be paid to careful observation, analysis of causes, early and timely prevention and treatment.

2.6 Application of plant growth regulators proper application of plant growth regulators to regulate growth can prevent leaves from falling. Adequate fertilizer and water, spring and autumn vigorous growth period, can be sprayed paclobutrazol, dwarf and other retarders to control growth and enhance tree potential. Once the banyan tree has fallen leaves, it can be sprayed with anti-falling hormone, cytokinin and so on. The specific type and concentration of application should depend on the specific situation. At the same time, the disease should be treated comprehensively from the aspects of soil, fertilizer, water, management and so on.