Reasons and Solutions for Cactus Yellowing Leaves
As a representative of desert plants, the cactus has become the first choice for新手 plant cultivation due to its strong vitality. However, when the seemingly sturdy cactus shows signs of yellowing leaves, it often indicates serious issues in the maintenance process. This article systematically analyzes the causes of yellowing leaves and provides detailed strategies with illustrations to help you quickly rescue the health of your succulent plants.
Yellowing Leaves Caused by Improper Root Maintenance
Root Rot Crisis Due to Soil Waterlogging
The cactus's native desert environment has given it drought-resistant characteristics, and long-term immersion of the roots in water can lead to respiratory obstruction. Typical symptoms include the base of the cactus becoming soft and the spacing between spines abnormally widening. You need to immediately remove the pot, trim the rotting roots, retain the main root length of 3-5cm, and replant using granular soil containing 50% vermiculite, keeping it completely dry for the first 3 days.
Yellowing Leaves as a Signal of Nutritional Imbalance
During the growing season of spring and autumn, it is necessary to supplement with slow-release fertilizer. When there is a lack of nitrogen and phosphorus elements, the cactus will show a uniform light yellow color. It is recommended to adopt the principle of "applying thin and frequent fertilization," using a mixture of bone meal and decomposed sheep manure at a ratio of 1:3 as a base fertilizer, combined with watering diluted fish protein liquid fertilizer every half month, taking special care to avoid the fertilizer from contacting the cactus's epidermis.
Environmental Factors Leading to Yellowing Leaf Lesions
Sharp Temperature Fluctuations
In the winter low temperature period (＜10℃), cold injury yellow spots can occur, while in the summer high temperature (＞35℃), it can lead to metabolic disorders. It is recommended to use the "stepwise temperature adjustment method": natural maintenance in spring and autumn, shading 60% at noon in summer, and setting up a simple insulation shed in winter to maintain a temperature of 12-15℃. When local yellow spots are found, immediately cut off the lesion tissue with a disinfected blade and apply carbendazim powder to the incision.
Simultaneous Harm from Pests and Diseases
Scales吸食汁液会造成星状黄斑，需用75%酒精棉签物理清除后，喷洒印楝素溶液。Root nematode infections require replacing all the potting soil and soaking the roots in avermectin solution for 30 minutes. For routine prevention, you can sprinkle diatomaceous earth on the surface of the potting soil every month to form a protective layer.
By scientifically diagnosing the causes of yellowing leaves and taking targeted measures, combined with the watering principle of "thoroughly wetting when dry" and the environmental control of "warm in winter and cool in summer," 90% of yellowing cacti can recover their green color within 2 months. It is recommended to save this article with its illustrations as a symptom comparison manual, regularly check the color changes at the base of the plant, and keep the desert spirit vibrant.