Control of Silver Leaf Disease of planting Pear trees

In recent years, silver leaf disease of pear trees occurred widely in some areas of our city. This disease is a destructive fungal disease. When it occurs seriously, it can cause pear orchard failure within a few years. The diseased pear trees are weak. The yield is reduced, and the seriously ill trees die after 2-3 years, seriously affecting pear production.

I. Symptoms of harm

Leaf forging disease not only damages pear trees, but also peach, apple, jujube and other fruit trees. The symptoms of the damaged fruit trees were mainly manifested on the leaves and branches. Under the action of the pathogen, the epidermis and mesophyll tissues of leaves are separated, and the gap is filled with air. Due to the reflection of light, the leaves are pale gray and slightly silvery white, so it is called silver leaf disease. The symptoms on branches are mainly manifested in xylem. The pathogen can spread upward to 1-2 years old branches in the xylem of the diseased tree, making the xylem of the diseased part brown, drier and smelly, but the tissue does not rot, but it can spread downward to the root. The diseased root is more rotten.

Affected fruit trees often show symptoms from one branch first, and then gradually increase until the whole plant is infected. The diseased trees germinated slowly, the leaves and fruits became smaller, and the tiled purple-gray fruiting bodies could be produced on the dead trees, but the fruiting bodies did not occur on the non-dead trees.

II. Rules of occurrence

The pathogenic bacteria of silver leaf disease belong to Basidiomycetes, Hymenomycetes, non-brown fungi, purple gum leather fungus, the optimum temperature range is 26℃. In winter, basidiospores overwintered on the xylem of diseased branches or dead branches, spread with airflow and rain, and invaded infected plants from wounds when conditions were suitable. Generally, May to June and September to October are rich in nutrients, which is the most suitable period for pathogen infection and the key period for prevention and control. It takes 1-2 years for the infected fruit trees to appear symptoms, which brings certain difficulties to the prevention and control work. Therefore, preventive measures should be taken for fruit trees in the affected areas.

III. Comprehensive platform prevention and control

1. Agricultural ecological prevention and control, strengthening orchard management

① Apply fully decomposed organic fertilizer, improve soil, enhance tree vigor and improve tree disease resistance.

② Flat and low-lying orchard, strengthen drainage facilities to prevent ponding in the garden and poor growth of fruit trees.

③ Protect the tree body; prevent and control other branch diseases and insect pests, reduce wounds, and prune lightly. It is not recommended to replace high grafting in the ward.

④ For dense orchards, transplant properly to achieve reasonable density and avoid mutual friction to cause wounds.

2. Artificial control

① For seriously ill trees and dead trees, dig out the roots, dig out the roots, take them out of the orchard and burn them in a centralized way, and disinfect the diseased holes with quicklime.

(2) Clean up orchards, eliminate residual branches, diseased leaves and diseased roots, and remove the source of disease.

(3) After soil disinfection, replanting other non-Rosaceae fruit trees and carrying out orchard transformation.

3. Chemical control

① Take branch-breaking therapy for those with few diseased branches, that is, saw off the diseased branches, pay attention to sawing off all the discolored parts of xylem, and smear the wound with Bordeaux pulp or 10 Baume stone sulfur mixture or 20% Sporing 1000 times solution to inhibit the spread of germs.

(2) The lightly infected plants should be air-dried, and then sprayed with 20% Sproling 3000 times solution and irrigated at the same time, or perforated with 18-hydroxyquinolin sulfate (this medicine needs to be imported and expensive).

Before fruit trees germinated, applying 50g Baitan or Subaoli fungicide per mu of soil had obvious control and prevention effects.