Control methods of yellow leaf disease of peach trees with yellowing, white blight, death and shedding

Peach yellow leaf disease, also known as chlorosis, iron deficiency, is a physiological disease. In recent years, the disease has a tendency to aggravate and spread, some individual plants are yellowing, some occur in pieces, or even the whole garden, which is not conducive to the normal growth and development of peach trees, which should be paid attention to.

Peach yellow leaf disease

1 symptoms: most peach trees begin to develop from the top leaves of new shoots, and gradually develop to the base, showing symptoms before the leaves grow. In the early stage of the disease, the mesophyll is yellow first, but the leaf vein and its two sides are still green, resulting in a green network on the leaf surface. In the later stage, with the development of the disease, the chlorosis aggravated, the whole leaf became white, the leaf edge became scorched, the leaf edge and leaf tip appeared rust-brown necrotic spots or patches, the lateral veins of leaves also turned yellow, the tip of new shoots withered, and the middle and upper leaves fell early. When the occurrence is serious, the tree is weak, which affects the quality of flower bud, the yield and quality of peach, and leads to the death of the whole tree.

2 regularity and causes of the disease: the occurrence of the disease is related to factors such as lack of iron or obstruction of iron absorption.

(1) malnutrition: no organic fertilizer for many years, a large number of chemical fertilizers, too much magnesium and manganese in the soil, resulting in the lack of iron, causing yellow leaves, we should pay attention to formula fertilization.

(2) soil salinization: in salinized soil, soluble divalent iron is converted into trivalent iron, which is not easily absorbed by trees, resulting in iron deficiency in peach trees, such as calcareous soil, soil alkali, water quality, dry weather, water evaporation, salt rising to the soil surface, low-lying land, high groundwater level, salt accumulation on the surface, etc., all factors that aggravate the degree of soil salinization can lead to the occurrence of the disease.

(3) soil hypoxia: such as soil viscosity and weight, poor drainage, high soil moisture, low amount of organic fertilizer, etc., all the factors affecting soil permeability may aggravate the occurrence of the disease.

(4) improper fertilization: peach roots are sensitive to external factors, such as the application of unmature human feces and urine, partial application of nitrogen fertilizer, chlorine-containing fertilizer or urban garbage fertilizer, etc., can cause damage to the roots, affect the root absorption of nutrient elements, and cause yellow leaves.

(5) improper pruning: for young and prosperous trees, do not pay attention to summer pruning and regulation, resulting in closed orchards, poor ventilation, resulting in yellow leaves. On the other hand, excessive retraction will also make the leaves yellowing.

(6) ineffective pest control: the lack of timely pest control can weaken the tree potential and aggravate the development of the disease, especially root rot, root cancer, gum disease, peach red neck longicorn beetle and other diseases and insect pests will affect the growth and development of peach trees and cause yellow leaves.

(7) other reasons: planting peach varieties susceptible to yellow leaf disease; planting peach seedlings with diseases and insects; not avoiding the original garden and cultivating in situ.

3Prevention and control measures:

(1) improve the soil. In saline-alkali soil, planting green manure, intercropping legumes, increasing organic fertilizer, digging trenches and draining alkali, mixing sand to change stickiness and so on.

(2) supplement iron. Before germination, the distance from the trunk is about 1m, and the radial groove of 15cm is dug deep along the main branch. Each peach tree is dissolved with 0.5kg Guoguang 20kg water, then poured into the ditch and filled with water, or mixed with organic fertilizer in autumn, 20ml 30kg per mu. During the growing period, the foliar spray of ferrous sulfate solution was 300 times, once every 15 times every 20 days, a total of 3 times. Or spray 0.1%-0.2% chelated iron solution once every 7 days for a total of 3 times.

(3) increase the application of organic fertilizer. Rotten farm manure was applied to increase soil permeability, improve soil physical and chemical properties and increase the content of organic matter. Farm manure is mostly acidic, which can improve alkaline soil. From September to October, 5000 kg per mu. It is forbidden to apply chlorine fertilizer and garbage fertilizer, after which it should be watered. After flowering to the hard core stage, watering is not too frequent, if it is not very dry, it can not be watered, and the trees will not be watered after flowering.

Peach trees loosen the soil

(4) do a good job of ploughing and loosening the soil. In order to increase soil permeability and do a good job of ploughing and loosening the soil, the soil should be loosened after each watering. Especially in the rainy season or waterlogging, drainage should be done in time, and the method of ramming the soil should be adopted to increase the soil permeability.

(5) Open the light path and increase the tree permeability. Especially young and prosperous trees, timely do a good job in summer pruning and regulation, open the light path, avoid canopy closure, and do a good job in ventilation and light transmission.

(6) do a good job in disease and pest control. Give priority to prevention, combined with prevention and control, timely control of diseases and insect pests, especially red-necked longicorn beetles, once eaten into the tree trunk, dichlorvos or aluminum phosphide can be fumigated with dichlorvos or aluminum phosphide. Specific methods: wrap the tablets with cloth, put them into the wormhole, then add water, bury them with soil, or add water with pyrethroids, then insert them into the hole with syringes and apply mud to the mouth.

(7) selecting disease-resistant varieties. Such as Honggang Mountain, Tianwang Peach, August Crispy, Chinese Peach King, etc.; avoid continuous cropping cultivation and keep a good quarantine pass.