Causes of blackening of Ping An tree trunk
As a common leaf-viewing plant in the home, Ping 'an tree is deeply loved for its tall and straight tree shape and auspicious meaning. However, blackening of the trunk often occurs during maintenance, which not only affects the appearance, but also may endanger the life of the plant. This paper will systematically analyze the causes and countermeasures of blackening of Pingan Tree trunk through pathological analysis combined with practical maintenance experience. 1. Analysis of pathogenic blackening diseases 1.1 Infection characteristics of brown spot disease When the environmental humidity continues to exceed 70% and ventilation is poor, the brown spot disease will invade through stomata. At the beginning, pin-tip-shaped black spots appeared on the trunk, and as the disease progressed, a round spot with a diameter of 3-5mm formed with a radial brown halo on the edge. The bark at places where the disease spots are concentrated will crack lengthwise and brown juice will flow out. 1.2 The comprehensive prevention and treatment plan immediately isolates the plants when the disease is discovered, uses alcohol-disinfected scissors when pruning, and applies thiophanate-methyl ointment to the incision. Alternate spraying of 25% azoxystrobin suspension at 1000 times and 50% carbendazim wettable powder at 800 times every week, and significant improvement was seen after 4 weeks of continuous treatment. 2. Blackening caused by pests 2.1 Hazard identification of scale insects Scale insects absorb tree sap through piercing and sucking mouthparts, and the honey dew they secrete will induce coal pollution disease. Black mold can be seen where the insects gather, and black spots appear on the surface of the trunk. When the pest is severe, white waxy shells can be seen covering the branches 'junctions. 2.2 When the number of insects per plant in the hierarchical management strategy is less than 20, a cotton swab can be dipped in 75% alcohol and killed. For moderate insect pests, use 22% Thiacanthong·HCF SC to spray the entire plant with 2000 times solution. Root irrigation is recommended for severe infections: use 40% chlorpyrifos EC to irrigate roots at a ratio of 1:1500, once every 15 days for three consecutive times. 3. Improper maintenance leads to black trunks 3.1 Water management points: Ping An tree root systems must be kept in a "moist but not wet" state. Keep the water content of basin soil at 40-50% in spring and autumn, and no more than 60% in summer. It can be judged by the "knocking on the basin and listening to the sound method": water needs to be replenished if the sound is crisp, and water is suspended if the sound is dull. When water accumulation occurs, immediately remove the pots and dry the roots, and replace the substrate containing 30% perlite. 3.2 Environmental regulation guidelines keep the temperature difference between day and night between 5 and 8℃, and no lower than 10℃ in winter. The light intensity is controlled at 15,000 - 25,000 Lux, and 40% of the sun needs to be shaded in summer. Use an EC value detector to monitor soil salinity every month. Leaching treatment should be carried out when the EC value is greater than 1.5mS/cm.
Through scientific diagnosis and precise prevention and control, the problem of blackening of Pingan Tree trunk can be effectively controlled. It is recommended to conduct a systematic inspection every month: look at the color of the bark, touch the humidity of the substrate, and smell the smell of the soil three times. Combined with the regular use of EM bacterial solution to irrigate roots, it can enhance plant stress resistance and fundamentally prevent the recurrence of black stem phenomenon.