What's wrong with the black tip of the orchid?
Black tips on orchid leaves are a common problem that plagues many orchid friends. This phenomenon not only affects the ornamental value, but also is a health warning signal sent by the plants. This paper analyzes the four core causes and combines years of practical experience in horticulture to systematically elaborate on the prevention and control strategies for the black tip problem of orchids. 1. Improper light management causes black tips 1.1 Strong light burn mechanism Orchids are typical shade plants, and their mesophyll cells are sensitive to ultraviolet light. Experimental data show that when the light intensity exceeds 30000Lux, the chloroplast structure will be damaged within 2 hours. Under direct sunlight at noon in summer, leaf surface temperatures can rise sharply by 8-10 ° C, directly leading to cell dehydration and necrosis. 1.2 The scientific lighting plan recommends using the "morning and dusk supplement light method": receive scattered light before 9:00 and after 16:00 every day and use it with the sunshade net (recommended density of 75%). Winter can be extended to 5 hours per day, and 360-degree pot turning operation is used to ensure that the plants receive even light. 2. Dual effects of humidity imbalance 2.1 Air humidity control The humidity of orchids 'native environment is between 70-85% all year round. When the air humidity is less than 50% and the temperature is more than 28℃, the leaf transpiration rate is increased by x times, causing vascular bundle embolism at the leaf tip. It is recommended to use an ultrasonic humidifier in conjunction with a hygrometer for monitoring to keep the air humidity at 5 cm above the substrate stable. 2.2 Leaf water replenishing skills Use an atomizing spray can (water particle diameter ≤50μm) to spray the leaves in the morning, paying attention to avoid new leaf buds. 0.1% fish protein liquid fertilizer can be added to replenish water and nutrients. 3. Temperature stress coping strategies 3.1 Low temperature and freezing injury protection When the environmental temperature is less than 5 ° C for 48 hours, the permeability of cell membranes increases, resulting in the outflow of electrolytes. It is recommended to adopt the "gradient insulation method": the triple protective structure of outer basin + middle layer perlite + inner layer water moss can increase the rhizosphere temperature by 3-5℃. 3.2 When extreme weather plans encounter cold wave warnings, apply 0.2% potassium dihydrogen phosphate solution 72 hours in advance to enhance cell stress resistance. At the same time, PE film is used to build temporary insulation sheds, paying attention to retaining ventilation pores. 4. Root Health Management System 4.1 Scientific watering cycle adopts the "bamboo stick detection method": Insert the disinfected bamboo stick into 2/3 of the substrate, and observe the traces of humidity after 20 minutes. Keep it in a "moist but not wet" state in spring and autumn, increase ventilation in summer, and extend watering intervals in winter. 4.2 The emergency treatment of rotten roots found that black tips were stopped immediately, and the "three-level root pruning method" was used: ① Cutting off browned tissue ② soaking in 1:2000 potassium permanganate ③ applying charcoal powder to promote healing. After changing pots, the roots were irrigated with EM bacterial solution to rebuild the rhizosphere microbial community.
Through systematic environmental control and precise maintenance, it can not only effectively control black tips of orchids, but also comprehensively improve plant resistance. It is recommended that Lanyou establish a maintenance log, record temperature and humidity data, and gradually master the growth rules of the plant to keep the orchids in the best viewing state.