2024 Author: Gavin MacAdam | [email protected]. Last modified: 2023-12-16 13:38
The most dangerous disease on a pear is cancerous lesions. The fight against them is difficult due to the deep penetration of the pathogen into the soft tissues of the plant. To determine the harmful factor, it is necessary to know the signs of the disease in order to immediately begin treatment
Types of cancerous lesions
There are 4 types of cancer on the pear:
• black;
• ordinary (European);
• root;
• bacterial.
Let us consider in more detail the signs of diseases.
Black cancer
The "culprit" is an imperfect mushroom that infects the bark of the trunk, main branches, flowers, leaves, and fruits. Reddish spots that turn brown over time appear on the leaf plates. Green mass, fruits fall prematurely.
On a sick pear, areas of the bark, branches die off, cracks and wounds form. If severely damaged, the entire tree dies. The fungus enters tissues through sunburn damage, frostbite, causing infection.
A distinctive feature of the disease is brownish-purple depressed spots with concentric zones. Black dots, clearly visible on them, are receptacles (pycnidia) of the fungus. Diseased branches resemble burnt shoots during a fire.
European (common) cancer
The causative agent of the disease is a marsupial mushroom. A sure sign is the formation of an influx, deep cracks, sometimes reaching the middle of the trunk.
Penetrates into the plant through mechanical damage on branch cuts, forks of branches. Causes the death of internal wood, bark. The rest of the tree is not affected.
Hibernates on the bark with spores, mycelium. Spreads through the garden by insects and wind. An open form of cancer is found on the pear. In this case, deep, non-healing wounds are formed. The edges become wrinkled over time.
Measures to combat black, common cancer:
1. Strengthening pear immunity:
• selection of hardy varieties;
• timely filling of cracks, damage with garden varnish or RanNet preparation;
• correct pruning of knots using putty;
• fight against pests damaging bark, wood;
• treatment of diseases causing cracks;
• whitewashing the trunk, the main branches with slaked lime with the addition of copper sulphate as a prevention of sunburn and frost.
2. Cleaning the bark to healthy tissue, disinfection with copper sulfate or boric acid.
3. Putting the cleaned wound up with nigrol ointment or a mixture of mullein and clay.
Root cancer
The causative agent of the disease is a rod-shaped bacterium. It develops on the roots, the basal neck of the pear, getting through the wounds, it causes the proliferation of cells. At first, the growths are small, soft, gradually increase in size, and grow stiff.
The disease is highly prevalent on slightly alkaline, neutral heavy clay soils. Pear seedlings sick with root cancer do not take root well, they often dry out. New plants are infected through the soil in which the pathogens hibernate.
Bacterial cancer
The culprit is a rod-shaped bacterium. It affects flowers, leaves that turn brown dry out. The diseased parts of the plant do not fall off; they hang on the pear until autumn.
Through the vessels, the infection from the leaves passes into the petioles, shoots, and main branches. When the shoots are cut, vascular necrosis is clearly visible in the form of a solid ring. When infestation is low, small, isolated dots appear.
On the branches, the trunk of the tree, oval depressed spots of a brownish-pinkish shade with a cherry-purple border around the edges appear. The wood softens, becomes moist, brown. Bacteria multiply rapidly in rainy weather and are carried by insects.
Measures to combat root, bacterial cancer:
1. Timely pruning of diseased branches with little capture of healthy tissue.
2. Disinfection of a wound with carbolic acid or copper sulfate.
3. Acquisition of healthy planting material.
4. Disinfection of roots for 5 minutes in copper sulphate, followed by rinsing with water.
5. Spraying with Bordeaux liquid.
Cytosporosis (infectious desiccation)
The cause of the disease is an imperfect mushroom. It manifests itself on boles, branches, young shoots. Individual affected areas dry out. Black dots are clearly visible on them - mushroom containers.
The bark remains brownish red. When separated from a branch, it becomes wet. Spores, mycelium overwinter on the branches. Weakened plants are affected by cytosporosis. From the bark, the fungus passes into the wood, leading to the drying out of the entire branch.
Control measures:
1. Increasing the pear's resistance to unfavorable factors.
2. Pruning, burning diseased branches.
3. Treatment. Disinfection of sections with copper sulphate, putty with garden varnish or RanNet preparation.
We will consider pear spots in the next article.
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