Causes and treatment methods for yellow leaves in four seasons
As a common aromatic plant in the courtyard, fragrant leaves should be its distinctive feature. When abnormal yellowing of leaves is found, it often indicates that the plant is in a sub-healthy state. This article will systematically analyze the five key incentives and provide highly operable solutions to help you recreate the vitality of the Four Seasons Gui. 1. Soil environment imbalance 1.1 Causes of pH imbalance The root system of Sijimei is extremely sensitive to soil pH. When the medium is alkalized (pH>6.5), the availability of iron is reduced, resulting in inhibition of chlorophyll synthesis. Daily watering hard water containing calcium and magnesium ions will intensify the soil alkalization process. 1.2 The soil improvement plan uses 0.2% ferrous sulfate solution to irrigate roots every month and uses pine needle soil to cover topsoil. It is recommended to change the pots every two years in spring, using a ratio of peat soil: humus soil: perlite =5:3:2. 2. Misunderstandings in light management 2.1 Analysis of light intensity requirements for the four-season cinnamon positive shrubs require more than 4 hours of direct light per day. Long-term placement in the shade environment will lead to insufficient photosynthetics, which is manifested by thin and yellowing new leaves. 2.2 Scientific lighting skills for full sunshine maintenance in spring and autumn, and 30% of the sun is required from 11 to 15 o'clock in summer. Use the retraction pruning method to remove the inner chamber branches so that the light transmittance of the crown reaches more than 40%. 3. Precise control of water and fertilizer 3.1 The golden rule of watering implements the principle of "seeing dry, seeing wet", and waits until 2cm of topsoil is dry before pouring thoroughly. Standing water for more than 24 hours can cause root rot, which is manifested by yellowing and curling of leaf tips. 3.2 Fertilizer ratio plan Apply special fertilizer for osmanthus fragrans (N-P-K=18-6-12) every 15 days during the growth period, and add potassium dihydrogen phosphate (1000 times solution) during the flower bud differentiation period. Stop fertilizer and protect roots in winter. 4. Comprehensive disease control 4.1 Identification of yellowing disease Fungal yellowing disease is characterized by irregular yellow spots on leaves, gradually expanding and accompanied by falling leaves. High humidity (RH>75%) can easily induce the disease. 4.2 Three-step prevention and control method ① Remove and destroy the diseased leaves in time ② Spray difenoconazole (1500 times solution) ③ Improve ventilation conditions and keep the plant spacing above 80cm. 5. Physiological yellow leaf treatment 5.1 Metabolism rules Natural yellowing of old leaves over two years old is a normal phenomenon. It is usually concentrated at the base of branches, and the monthly replacement rate should be less than 5%. 5.2 Trim specifications Use alcohol-disinfected pruning shears and cut obliquely 45° along the base of the petiole. Spray mancozeb after pruning to prevent wound infections.
By systematically diagnosing the causes of the yellow leaves of Siji osmanthus, we found that 80% of the problems stem from improper regulation of the cultivation environment. It is recommended to establish a maintenance log to record data such as water and fertilizer management, pest and disease occurrence, and adjust maintenance strategies in a timely manner based on plant response. When the proportion of yellow leaves exceeds 30%, an emergency treatment plan needs to be activated, and root washing and soil replacement operations should be carried out if necessary.