Occurrence and Control of Zinc deficiency in Apple

Apple is vulnerable to disease in the process of planting, especially because of the physiological disease caused by zinc deficiency, which is also called lobular disease, which will cause apple tree leaves to turn yellow or grow relatively small. Let's take a look at the occurrence and prevention of zinc deficiency in apples.

I. symptoms of zinc deficiency in apples

Zinc deficiency in apples was mainly manifested in new shoots and leaves, especially in the top shoots around the crown. The diseased branches germinated late in spring, the internodes of the new shoots became shorter, and the leaves were small and clustered in the shape of a rosette. The diseased leaves are narrow and slender, hard and brittle, the leaf edges are curled, the leaves are yellowish green or uneven, and the veins become lighter. Diseased trees have fewer flower buds, small and light flowers, low fruit setting rate or small deformities. The leaves of seriously diseased trees gradually fall off from the base of the new shoots, the crown is empty, the root system is underdeveloped, and root rot is easy to occur.

II. Prevention and treatment of Zinc deficiency in Apple

1. Control the spread of virus and reduce the harm of lobular disease caused by virus: for the lobular disease caused by virus, the spread of virus should be strictly controlled in production to prevent the spread of lobular disease. If it is confirmed that the lobular disease is caused by the virus, the plants suffering from the disease should be excavated in time, and if the harm is mild, special tools should be used during pruning to prevent the spread of the virus, and at the same time, the diseased plants should be corrected by spraying virulent and other agents.

2. Nourish the symptoms, overcome the phenomenon of element deficiency and promote the healthy growth of leaves: for the phenomenon of lobules caused by element deficiency, we should carefully study the symptoms in production, treat the symptoms and overcome the adverse effects of element deficiency. For the leaflets caused by nitrogen deficiency, we should apply more organic fertilizer and supplement nitrogen fertilizer, especially the supplement of available nitrogen fertilizer, in order to promote the leaf to return to normal, while applying nitrogen fertilizer to the root. It can be corrected by foliar spraying 0.3% 0.5% urea. For the leaflets caused by phosphorus deficiency, on the basis of increasing the application of organic fertilizer, attention should be paid to increasing the amount of phosphorus fertilizer, so as to supplement the content of phosphorus in the soil and improve the supply capacity of phosphorus. 0.3%-0.5% potassium dihydrogen phosphate can be sprayed on the leaves. For the leaflets caused by zinc deficiency, zinc sulfate of 0.5~1kg can be added to each plant according to the size of the tree. Before the tree sprouts in early spring, 0.3% zinc sulfate + 0.3% urea is sprayed on the trunk and main branches. After germination, 0.3% 0.5% zinc sulfate solution is sprayed on the leaf surface for correction. According to practice, it is more effective to spray 0.2%-0.3% urea when spraying zinc on the leaf.

3. When selecting excellent varieties to build an orchard, select varieties with strong comprehensive resistance, such as Red Fuji and Marshal, and choose places with high terrain, good drainage, sunny, ventilated and ventilated. In addition, do not build apple orchards in continuous cropping orchards or nurseries.

4. Turn the soil deeply, apply more organic fertilizer, promote the robust growth of roots and improve the absorption function of trees, so as to facilitate the healthy growth of leaves: for terraced orchards, pay attention to deep ploughing before the establishment of the orchard. If there is no deep ploughing during the construction of the orchard, a deep ploughing of the whole orchard should be carried out within 2-5 years after planting, especially after soil removal. To ensure that the depth of deep ploughing is above 60cm, if it can be combined with deep ploughing, apply a large amount of organic fertilizer. The rhizosphere growth environment can be optimized and it will have an obvious effect on correcting the occurrence of lobule phenomenon.

5. Chemical control. According to the demand characteristics of zinc in apple trees, the occurrence of apple zinc deficiency can be effectively prevented by supplementing zinc fertilizer. Combined with the application of base fertilizer in autumn, zinc sulfate 0.5~1kg was applied to each adult tree, it was effective in the second year and lasted for a long time, but it was poor in alkaline soil, so foliar zinc spraying should be carried out. Spray 3% zinc sulfate solution or 0.1% zinc sulfate solution after sprouting before the leaf buds of fruit trees begin to germinate. As nitrogen can promote zinc absorption, 0.2% zinc sulfate and 0.3% urea solution can be sprayed 20 days after apple blooming, which has a better effect on relieving symptoms.