Detailed Explanation of the Causes and Control Measures of Replant Disease in Orchards

In orchard cultivation, pest and disease control is one of the most critical aspects, and a common disease in orchards is replant disease, which refers to the phenomenon where the same piece of land is planted with fruit trees and then continuously planted with the same type of fruit trees, causing the growth of replanted fruit trees to be inhibited or pests and diseases to recur. So how should replant disease in orchards be controlled? Let's take a look together.

I. Disease Symptoms

Replant disease mainly manifests as weak growth of transplanted young trees, poor root development and root rot, slow new shoot growth, shortened internodes, leaf chlorosis, difficulty in fruit trees producing shoots, poor fruit quality, and the replanted trees becoming stunted small old trees; in severe cases, they gradually wither and die before reaching maturity, causing the orchard to decline prematurely and resulting in serious economic losses.

II. Causes

There are many reasons for the occurrence of replant disease in replanted orchards. First, the root system of old trees secretes toxic substances that inhibit the respiration of the root system of newly planted fruit trees, causing disease and death of the newly planted fruit trees. Second, there are relatively many nematodes and pathogenic microorganisms in the orchard soil, which cause relatively great damage to the root system of newly planted fruit trees, resulting in weak growth and poor development of the newly planted fruit trees. Third, the orchard lacks certain nutrient elements or has excessive nutrients, causing an imbalance in nutrient supply and thus slow plant growth.

III. Control Measures

1. Renewal and crop rotation

When renovating an orchard, it is necessary to persist in rotation rather than replanting. For example, if the previous crop was apple trees, then grapes, citrus, apricots, walnuts, persimmons and other fruit trees can be planted directly; however, if the previous crop was pear trees, then it is not suitable to plant stone fruit trees such as peaches, plums, apricots and cherries, and pome fruit trees should be planted instead.

2. Clearing the orchard and improving the soil

After old trees are dug out or nursery stock is removed from the field, the orchard should be thoroughly cleared, and residual roots, fallen leaves and weeds around the orchard should be gathered and burned. When planting fruit trees in the same place, the soil should be deeply turned and improved, residual roots should be removed, and at the same time the original fruit tree planting holes should be avoided and new holes should be opened for planting. After opening the holes, they can be disinfected, and then covered with plastic film, which can kill most nematodes, pathogens and microorganisms remaining in the soil. For acidic soil, lime can be spread to improve it.

3. Increasing application of organic fertilizer

Apply 100-150 kg of decomposed organic fertilizer into newly dug planting holes. Without biased application of nitrogen fertilizer, increase the application of phosphorus and potassium fertilizer, and during the growing season spray amino acid compound micro-fertilizer at a concentration of 300 times once every 15-20 days.

4. Disinfection and sterilization of nursery stock

Before planting, spray or soak the seedlings for 10-20 minutes with 3-5 degrees Baume lime sulfur mixture, or 800-fold Tuzet solution, or 1000-fold carbendazim solution, then rinse the roots with clean water, which can kill the pathogens carried by the roots.

5. Supplementing nutrients

Before replanting, it is best to sample and analyze the soil to understand the depletion or accumulation of nutrient elements in the orchard soil, and then determine the fertilization plan. According to the type and variety of the newly planted fruit trees, reasonably supplement and adjust the nutrient elements in the soil, with particular attention to the application of trace elements and organic fertilizer, to ensure the needs of fruit tree growth.

The above is an introduction to the causes and control measures of replant disease in orchards. We hope it can help you. For more related knowledge, please stay tuned to us.