To prevent the sudden death of grapefruit trees, it is essential to take preventive measures from the very beginning of winter, as waiting until other diseases appear is too late. Pomelo root rot primarily occurs during the summer and autumn rainy season. The disease typically affects the cortex and main roots near the girdling area, where the epidermis turns black and emits a foul odor. Microscopic examination of affected roots reveals pathogens such as "scytheid, filamentous mycelium fungi, and spores." Soil pH levels are usually between 5 and 6, indicating strong acidity, which contributes to the problem. Infected trees show symptoms such as weak growth, dying branches, and leaves that fall off, eventually leading to the tree's death, requiring excavation and replanting.
The causes of the disease include: 1) a virus-infested soil layer at a depth of 35 cm with acidic conditions. 2) Poor drainage in low-lying orchards increases the risk of infection. 3) Spraying paclobutrazol and using girdling methods can disrupt normal plant growth, preventing chlorophyll from being transported to the roots. 4) Improper use of chemical fertilizers like urea can lead to root rot and death. 5) Girdling young trees too low, near the grafting site, can cause saplings to die. 6) Lack of decomposed organic fertilizer weakens the tree's health. 7) Long-term girdling due to heavy fruit load and unstable winter temperatures can result in unhealed wounds, increasing mortality rates in spring.
To maintain healthy grapefruit trees, the following technical measures are recommended:
First, cultivate weeds during winter, apply lime for sterilization, avoid deep digging during fruiting, and only plow and weed around the canopy's edges to keep the tree vigorous.
Second, apply 0.5 to 1 jin of grapefruit lime per tree, avoiding overuse, which may cause boron deficiency.
Third, use 5–6 kg of calcium magnesium phosphate fertilizer per tree, and if possible, add wood ash to neutralize soil acidity.
Fourth, when dead trees are found, remove them and replant. Excavate diseased plants and contaminated soil, and disinfect seedling roots with Sie Lisan or treat the soil accordingly.
Fifth, apply Fomefia 500 times diluted for irrigation, or use 800 times diluted enemy pine powder, or a 1:1:10 Bordeaux mixture. Apply a 70% thiophanate solution after scraping off rotted and decayed bark.
Sixth, apply urea as top dressing after rain, and water it in on dry days. Avoid deep application, as it can cause root ulcers and lead to tree death.
Seventh, each year in early spring and early summer, treat the roots and stems with pesticides such as Fumei double at 500 times dilution or 1:100 Bordeaux mixture, applying enough liquid to cover 10–12 trees per 100 kg of solution.
Eighth, for long-term fruit-bearing trees with weak growth, delay girdling until after the winter solstice. Girdle branches but leave a sprig untouched. Increase the girdling area on saplings and avoid close proximity to the grafting site to prevent sudden death.
Ninth, limit the use of paclobutrazol to avoid excessive growth inhibition and maintain tree vitality.
Electronic Chemicals Series
Also known as electronic chemical materials. Generally refers to the electronics industry uses specialized chemicals and chemical materials, that is, electronic components, printed circuit boards, industrial and consumer production and packaging of various chemicals and materials. It can be divided into substrates, photoresists, electroplating chemicals, packaging materials, high purity reagents, specialty gases, solvents, pre-cleaning dopants, flux masks, acids and etchants, electronic adhesives and auxiliary materials Other categories. Electronic chemicals with many varieties, high quality requirements, small dosage, demanding on the cleanliness of the environment, product replacement fast, large capital investment, higher value-added products, etc., these characteristics with the development of micro-processing technology more and more obvious.
Electronic chemicals, also referred to as electronic chemical materials, refer to the fine chemical materials that are used in the electronics industry. The electronic chemicals are a kind of special chemicals. As far as the properties of the production process are concerned, they belong to the fine chemical industry. In terms of product use, Belongs to the electronic material industry. According to the classification standard of China's national economy, the electronic chemicals industry belongs to "Specialized Chemical Products Manufacturing Industry" (2662); according to the "Guidelines for Industry Classification of Listed Companies" promulgated by China Securities Regulatory Commission in April 2001, it belongs to "Specialized Chemical Products Manufacturing Industry" C4360 ). They include integrated circuits and discrete device chemistries, such as chip production photoresist, ultra-clean high-purity reagents, ultra-clean high purity gas, plastic packaging materials; color TV with chemical materials, such as color phosphor, CPT Supporting the water-soluble resist, high-purity inorganic salts, organic films, etc .; chemical materials used in printed circuit boards, such as dry film resist, ink, chemical and electroplating copper plating solution and its additives, surface mount process conductive paste , Cleaning agents, liquid solder resist photoresist, adhesive patch, conductive adhesive, solder paste, pre-coated flux, clean and water-based process flux; liquid crystal display devices with chemical materials, such as liquid crystal, photoresist , Oriented films, adhesives, slurries, electrolytes, films and encapsulants, polarizers, etc .; polishing materials, ect.
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