Why the leaves of crabapple trees turn yellow
As a common ornamental plant in the courtyard, crabapple trees are deeply loved for their gorgeous flowers and elegant tree shapes. However, when the leaves of crabapple were found to gradually turn yellow, it not only affected the ornamental value, but also predicted plant health problems. This paper will systematically analyze the causes of yellow leaves of crabapple trees and provide scientific maintenance plans. Deep analysis of the causes of yellow leaves of crabapple trees. Water management is unbalanced. The root system of crabapple trees is extremely sensitive to water and needs to maintain soil micro-tide during summer dormancy. When the water content of the basin soil is greater than 70%, the root system becomes browned and rotted due to hypoxia, which shows that the lower leaves are the first to turn yellow and fall off. Excessive water control during the low temperature period in winter causes soil hardening. When the root hairs cannot absorb water, the edges of new leaves will appear scorched. Nutrient deficiency symptoms can be judged by intervein yellowing, while the overall yellow-white of the new leaves indicates iron deficiency. When soil pH>7.5, iron will be fixed in an unabsorbable state. It is recommended to use iron EDTA chelate solution to irrigate roots every quarter, and apply magnesium sulfate (1 g/liter) to foliar spray. Misunderstanding in light control, crabapple is a positive tree species, but avoid direct light. In spring and autumn, light needs to be scattered for 6 hours. In summer, a sunshade net should be used to filter 30% of the light from 10:00 to 15:00. Long-term exposure to an environment of <2000lux will lead to inhibition of chlorophyll synthesis, which is manifested by uniform yellowing of the entire leaves. Reasons for yellowing of crabapple leaves: Technical points for fertilization During the growth period (March to May), the principle of "thin fertilizer and frequent application" should be followed, water-soluble fertilizer with N-P-K=15-5-10 should be used, and the concentration should be controlled at 800- 1,000 times. Missy application of nitrogen fertilizer during dormant period will cause leaf tips to turn yellow. It is recommended to apply phosphorus and potassium fertilizers in winter to enhance cold resistance. Scientific Maintenance Implementation Plan The intelligent irrigation system installs soil moisture sensors to maintain the substrate moisture content within the range of 45-60%. Use bottom infiltration irrigation to avoid sunburn caused by residual water droplets on the leaves. Water is replenished once a week during the dormant period, and every 3 days during the growing period, until water seeps out from the bottom of the basin every time. Nutritional diagnosis and supplementation The soil EC value is tested in early spring every year, and the ideal range should be maintained at 1.2-1.8mS/cm. When yellow leaves are severe, multiple trace fertilizers containing iron, magnesium, and zinc (concentration 0.2%) can be sprayed on the leaves, and applied in conjunction with the application of humic acid to improve root absorption capacity. The optimization of the lighting environment adopts an adjustable sunshade system to maintain the light intensity at 30,000 - 40,000 lux in summer and replenish the light above 20000lux in winter. Turn the flowerpot 45 degrees every half of the month to ensure that the crown receives even light. Full-spectrum plant growth lights are required for north-facing balcony maintenance.
By establishing a three-in-one maintenance system of soil moisture monitoring, nutrient element detection, and light intensity control, the yellow leaf phenomenon of crabapple trees can be effectively prevented. It is recommended to measure the SPAD value of leaves every month. When the chlorophyll content is less than 35, the maintenance plan should be adjusted in time to keep the crabapple trees in a healthy state.