Symptoms of decline of navel orange seedlings

Decline disease is a very susceptible disease of citrus fruit trees, which occurs all over the world and causes disasters in many areas. What are the symptoms of navel orange seedling decline disease?

First, what is a recession disease?

Citrus decay virus is a disease caused by citrus decay virus. The virus particles of citrus decay virus are linear and its length and width are 2000 nm × (10 ~ 12) nm. The long-distance transmission of citrus decline disease is through the transportation of poisonous seedlings and grafted materials, while the short-distance transmission in the field is caused by the tossing and turning of aphids among diseased plants, hidden disease plants and healthy plants, among which the transmission ability of orange aphid is the strongest.

After the disease, the xylem of the branch showed sunken spots and sunken grooves. When the damage was serious, the appearance of the branch was longitudinally concave and convex, the fruit became smaller and the tree potential became weaker.

Symptoms of decline of navel orange seedlings

The main results are as follows: 1. The crown is obviously short, the number of spring shoots is small and delicate, the gloss of leaves is poor, and the number of flowers is large.

2. The flower and fruit drop is serious, the fruit is less and the fruit development is rigid, the fruit is small, the navel is flat, and the fruit shape is not correct.

If the mature branchlets of one year or more are brittle and easy to break, they will make a "snapping" sound when they are broken, and the fracture surface is neat; the bark is relatively easy to peel off, and obvious pitting or grooves can be seen in the xylem.

Third, how to prevent and cure the degenerative disease?

1. Select disease-resistant rootstocks such as trifoliate orange, sour orange, red orange, orange and Goutou orange.

2. In the disease area, the seedlings are inoculated with attenuated strain first, which can avoid the infection of virulent strain.

3. Carry out quarantine to prevent the introduction of new virulent strains from abroad.

4. Timely control of vector insects and aphids

5. Collect ears from disease-free mother plants identified regularly by indicator plants as far as possible. Scions or seedlings that may be infected must be treated with 50 ℃ of humid and hot air for 7 hours and 22 hours.