There are many factors that cause yellow leaves of apple trees in summer, the more common ones are iron deficiency yellow leaf disease, apple mosaic disease, improper girdling methods, canopy closure, damage to leaf miners, orchard damage or excessive soil drought, etc. According to the symptoms of the yellow leaves of apple trees, the cause of the disease should be analyzed and targeted methods should be determined to correct and prevent it.
Iron deficiency yellow leaf disease
The occurrence of iron deficiency yellow leaf disease in apple trees generally began in late May. After entering the rainy season, the incidence of iron deficiency yellow leaf disease is more common, especially in the 1 and 2 year old saplings planted on the partially alkaline soil. Yellow leaf disease in apple trees mainly manifests on the young leaves of new shoots, and the symptoms of the new shoots are most pronounced during the vigorous growth period. The prevention and control method is: Spraying 0.1% to 0.2% ferrous sulfate or 0.3% urea plus 0.3% ferrous sulfate mixed solution (urea iron) or 200 to 300 times of ferrous fulvic acid to the branches with yellow leaves. Organic iron fertilizer.
Yellow leaves caused by mosaic disease
Apple tree mosaic disease also often causes yellow leaves of the fruit. The disease is caused by viruses and is difficult to eradicate. Strengthen management and strengthen tree vigor are the most important measures to prevent and treat the disease. For example, mosaic virus can be sprayed with drugs such as Trane and Virus. From the summer solstice to the equinox, generally before and after mid-July, 300 to 450-fold dilutions of "virus II" (or 15 kg of water per 40 g of "Virus 1") may be used. 0.5 kg of pure milk per barrel of water is added for spraying to effectively prevent and control fruit tree virus disease.
Yellow leaves caused by girdling
Generally adopts the standardized method to carry on apple tree girdling, after 10-15 days of girdling, there is a short blade slightly yellow leaf period. If the yellow leaves of the leaf after the girdling aggravate, it is necessary to pay close attention to wringing with plastic film. ), can also be mud coated after wrapping the plastic film to promote the healing of the ripping mouth. At the same time, the tree is sprayed with urea 300 times for 1 or 2 times (sprayed once every 7 days), or it can be sprayed 1000 times for Green Fenway No. 2 and watered and fertilized underground to prevent excessive drought and aggravate defoliation. happened.
Yellow leaves caused by canopy closure
Due to the large number of branches, the yellow leaves and deciduous leaves of the inner and lower branches of the tree branches are often created. The summer pruning to ensure the ventilation and light transmission in the canopy is the best way to prevent this phenomenon.
Yellow leaf caused by the damage of leaf miner
Generally, there are 2 or 3 leaves of the leafhopper moth on a leaf blade, which will cause yellow leaf defoliation. Spraying 2 to 3 times of diflubenzuron 3 from the end of May to the beginning of July can effectively control this pest.
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