What symptoms does fruit tree root nodule disease have? How to prevent and cure it?

The root nodule disease of fruit trees is a very common disease, which may reduce the yield or even lead to the death of fruit trees if it is not controlled in time. Therefore, fruit farmers must do a good job in prevention and treatment, so what are the symptoms of root nodule disease in fruit trees? How to prevent and cure it?

I. main symptoms of root nodule disease

Spherical or oblate spherical tumors are formed at the affected sites, with tumor sizes as small as beans and fists, and can be clustered by many small tumors into larger tumors with a diameter of tens of centimeters. The primary tumor is milky yellow and gradually changes from light brown to dark brown. The internal tissue is grayish white, soft or spongy. In the later stage, the internal tissue was lignified. The outer surface is rough and uneven. Produce some fine roots on or around its surface. The surface tissue of the mature tumor is ruptured, or rots from the surface to the center, and some tumors fall off from the base, and new cancers can be regenerated. After the occurrence of root nodule disease, the growth and development of fruit trees is seriously hindered, the tree potential is gradually weakened, the fruit is poor, and the quality is reduced. Therefore, orchard cultivation managers must pay attention to the prevention and treatment of root nodule disease of fruit trees.

2. Characteristics of root nodule disease of fruit trees.

The root nodule disease of fruit trees invades parasitic plants mainly through wounds. after invading the plants, the pathogens can propagate continuously in the parenchyma cells of the cortex and secrete irritants, which accelerate the division and proliferation of adjacent cells and form carcinomatosis. The incidence of root nodule disease of fruit trees has the following characteristics:

1. Damage can occur during the growing period every year, especially in August.

two。 Slightly alkaline soil is beneficial to the disease, but less acidic soil disease.

3. The sandy loam with high humidity is beneficial to the disease, and the clay heavy soil disease is less.

4. It is easy to cause disease when the wound is caused by seedling grafting, seedling, planting, burying the soil to prevent cold, ploughing and so on.

5. The degree of disease is different among different species. The disease of peach is more than that of apricot.

6. The degree of disease was different among different rootstocks. Sweet cherry with green skin cherry as rootstock is highly susceptible and mountain cherry as rootstock is highly resistant.

7. Disastrous weather aggravates diseases, such as frost injury, hail damage and so on.

8. Other diseases and insect pests lead to the increase of cancer, such as underground pests, nematodes and so on.

III. Prevention and control measures of root nodule disease of fruit trees

1. Disease-free rootstocks and disease-free scions were selected for self-propagating disease-free seedlings, and seedlings were raised in fields without disease history and trees. No or less chemical fertilizer should be applied to cultivate strong seedlings.

two。 The external purchase of seedlings should be guided by the principle of "five-no purchase", that is, do not buy seedlings raised in the same year and come out of the nursery in the same year, do not buy seedlings promoted by chemical fertilizer, do not buy seedlings with disease history and tumor, do not buy seedlings of susceptible rootstocks, and do not buy seedlings that suffer from hail damage, freezing injury and many underground pests.

3. Seedlings should be quarantined and quarantined. Carefully check the seedlings one by one, and burn the sick centrally (do not leave the disease later). The selected seedlings were soaked with "K84" biocontrol agent or treated with other drugs.

4. Before planting, the seedlings were treated before or during planting, the roots were dipped in copper sulfate 100 times solution for 10 minutes, washed and then dipped in Bordeaux pulp for protection, and 50% phoxim bait was used to control underground pests.

5. In order to prevent seedling injury, every effort should be made to prevent seedling injury in the links of seedling initiation, transportation, planting and management.

6. In order to prevent frost injury, special attention should be paid to cold prevention in seedling stage, and proper management measures should be taken in the adult stage to increase the ability of frost resistance.

7. After planting, check and colonize, once the diseased plant is found, it should be removed and burned immediately. To replace the original tree pit with new soil, it is best to replant it every other year.