1 Symptoms Zinc deficiency in apple trees is mainly manifested in shoots and leaves, and the tip of the periphery of the crown is most obvious. Diseased branches often show late germination, small and slender leaves, leaf margins upward, hard and brittle, yellowish-green leaf color or shade uneven; diseased nodes shortened. Due to the stagnant growth of this disease, new shoots can be made in the lower part of the disease but still show the same symptoms. Diseased branches are not easy to flower; even if there are flowers will appear small, light, not easy to set fruit; even if the fruit set, but also showed a small fruit and deformity. The diseased leaves are sparse and the yield is very low.
2 Causes of Disease The occurrence of zinc deficiency in fruit trees is related to a variety of factors: 1 Sandy orchard soil is thin, zinc content is low; or soil water permeability is good, and soluble zinc salt is lost due to excessive irrigation; 2 too much nitrogen fertilizer is used. The demand for zinc increased; 3Salt-alkali soil zinc easily fixed, can not be absorbed by the roots of fruit trees; 4 soil viscosity, living soil shallow, fruit tree roots are not well developed; 5 replanting apple trees in orchards or nursery plants prone to zinc deficiency.
3 Prevention and control methods Adding organic fertilizers, improving soil, and reducing the alkalinity of the soil are the basic measures for preventing and treating zinc deficiency diseases. At the same time, supplementing appropriate amount of zinc fertilizer can achieve ideal control effects. Specific methods: 1 before germination spray 3% ~ 5% zinc sulfate solution, or in the early stages of germination spray 0.1% zinc sulfate solution, 3 weeks after spraying 0.2% zinc sulfate plus 0.3% urea, to reduce the symptoms have a significant effect; 2 combination Applying organic fertilizer in spring and autumn, adding 0.25-0.5kg of zinc sulfate to each mature tree, effective for the following year, the effective period can be as long as 3 to 5 years, but the effect of saline-alkali soil is poor. 3 If zinc deficiency is caused by the lack of magnesium and copper, the effect of single application of zinc sulfate is not significant, and the compound containing magnesium, copper and zinc must be applied at the same time to obtain the effect.
2 Causes of Disease The occurrence of zinc deficiency in fruit trees is related to a variety of factors: 1 Sandy orchard soil is thin, zinc content is low; or soil water permeability is good, and soluble zinc salt is lost due to excessive irrigation; 2 too much nitrogen fertilizer is used. The demand for zinc increased; 3Salt-alkali soil zinc easily fixed, can not be absorbed by the roots of fruit trees; 4 soil viscosity, living soil shallow, fruit tree roots are not well developed; 5 replanting apple trees in orchards or nursery plants prone to zinc deficiency.
3 Prevention and control methods Adding organic fertilizers, improving soil, and reducing the alkalinity of the soil are the basic measures for preventing and treating zinc deficiency diseases. At the same time, supplementing appropriate amount of zinc fertilizer can achieve ideal control effects. Specific methods: 1 before germination spray 3% ~ 5% zinc sulfate solution, or in the early stages of germination spray 0.1% zinc sulfate solution, 3 weeks after spraying 0.2% zinc sulfate plus 0.3% urea, to reduce the symptoms have a significant effect; 2 combination Applying organic fertilizer in spring and autumn, adding 0.25-0.5kg of zinc sulfate to each mature tree, effective for the following year, the effective period can be as long as 3 to 5 years, but the effect of saline-alkali soil is poor. 3 If zinc deficiency is caused by the lack of magnesium and copper, the effect of single application of zinc sulfate is not significant, and the compound containing magnesium, copper and zinc must be applied at the same time to obtain the effect.