What should I do if the azalea leaves are black?
As one of the top ten famous flowers in China, rhododendrons are very popular among gardening enthusiasts for their colorful flowers. However, many flower lovers have recently reported that rhododendrons have blackened leaves, which not only affects the ornamental value, but also serves as a distress signal from the plants. Through analysis, it was found that the three main reasons for blackening rhododendron leaves are closely related to daily maintenance. 1. Improper water management triggers black leaves 1.1 Hazards of excessive watering Rhododendron is a shallow root plant. Excessive watering will cause the roots to fail to breathe. When the soil moisture exceeds 70%, the root system will gradually rot, manifested by blackening the edges of the leaves and spreading to the center. Through observation of leaf stomata, it was found that mesophyll cells were browned due to hypoxia. 1.2 The scientific water replenishment plan adopts the "see dry" method: watering every 3-4 days in spring and autumn, spraying in the morning and evening to increase humidity in winter, control the water to soil micro-tide. 2. Technical points for root restoration 2.1 Application of plant growth regulators When root damage occurs, it is recommended to use a compound preparation of IBA (indole butyric acid) and NAA (naphthylacetic acid): hormone type concentration ratio, frequency of use, rooting agent 1:1000, once a week, cytokinin 1:1500, once a day, 2.2 Microbial inoculants are used in conjunction with the use of beneficial bacteria such as Bacillus subtilis, which can improve the root restoration efficiency by more than 40%. 3. Disease leaf treatment and prevention system 3.1 Standardize the pruning of damaged leaves. Use disinfectant scissors to cut obliquely at 45° along the base of the petiole. After treatment, use 800 times carbendazim to apply the wound. Note that the amount of single pruning does not exceed 30% of the total leaf weight. 3.2 Four elements of environmental control: Maintain air circulation (wind speed ≤0.5m/s), maintain 60-70% environmental humidity, avoid direct light (light intensity 3000-5000LUX), control the soil PH value at 4.5-5.5 Through systematic maintenance measures, the blackening problem of rhododendron leaves can be significantly improved within 2-3 growth cycles. It is recommended to establish a maintenance log to record the plant changes after each treatment, and gradually understand the personalized maintenance needs of different rhododendrons.