Fire blight, or bacterial blight, is a dangerous disease of fruit trees. In addition to pears, it affects rowan and apple trees. Plants can be cured if the infection is detected early, at the very beginning of its spread. Otherwise, fire blight control becomes much more difficult. Within a short time, the pathogen spreads to healthy trees and completely destroys fruit crops.
Description of the disease
Bacterial infection typically affects young plants. Mature trees are more resistant to the pathogen, but are not immune. The danger of fire blight lies in the similarity of its symptoms to those of other diseases. Therefore, not all gardeners are able to diagnose it promptly, understand how to treat fire blight on pears, and take timely action.
Pathogen
American scientists were the first to discover the bacterium Erwinia amilovora, which causes fire blight. It causes the death of fruit trees. The disease is also known as "erwinia," after the bacterium's name. In previous years, the disease was widespread in Australia and America. Fruit trees showing signs of infection are now found in orchards across Russia.
A dangerous disease that causes widespread infection of fruit crops emerged in the southern regions of the country at the end of the last century. It continues to spread to other areas. The bacterium attacks all plant tissues, including those deep within the heartwood. The pathogen spreads through blood vessels. If treatment is not started promptly, the fruit tree dies within three years.
Causes of the disease
The Erwinia amilovora bacterium spreads from diseased plants to healthy ones in various ways. The primary vectors are insects and birds. Cracks, ulcers, or other mechanical damage to the bark facilitate infection. Windy weather also facilitates the spread of the disease. Trees are more susceptible to the pathogen if the soil beneath them is high in nitrogen. The disease often appears in orchards when already infected pear seedlings are planted there or when cuttings taken from infected plants are grafted.
Bacterial activity decreases during cool summers. Bacterial blight infection does not occur in winter. The following factors influence the rate of spread of the disease:
- a sudden increase in air temperature at the end of May or the beginning of June;
- prolonged rainy weather;
- distribution of bees and wasps.
Symptoms
The first signs of pear bud disease are drying and darkening of the buds. During the flowering stage, pear tree flowers darken and wither. After drying, the buds remain on the tree. The infection then spreads to the foliage and young shoots. Dark spots appear on all parts of the plant. Affected parts curl, become deformed, and dry out.
Developing fruits acquire a dark flesh color and gradually dry out. As the infection spreads to the trunk and large branches, the bark softens and becomes covered with brown streaks. When the active stage of the inflammatory process begins, droplets of a cloudy, light-colored liquid appear on the leaves and shoots. The exudate darkens and hardens when exposed to air. When the trunk becomes completely dark, the tree dies. The appearance of a pear infected with fireblight is shown in the photo below.
Methods of control
https://youtu.be/E_mxNedfTgw
Treating pears for fire blight is only possible at the initial stage of infection. The first symptoms of infection should be detected before more than 30% of the plant is affected. Fire blight is dangerous because its symptoms are similar to those of a fungal infection. Therefore, some gardeners treat pears for fire blight with fungicides, such as Skor or HOM. This treatment is ineffective, as these agents are only effective against Cytosporosis or Moniliosis.
Any treatment for fire blight is only effective for two weeks, from the start of sap flow until flowers bloom. During this period, bacteria emerge from their capsules and are most susceptible to treatment. It's important to treat the tree before sticky exudate appears on the bark. This fluid contains the majority of the bacteria. Precipitation and wind promote the spread of infection.
Chemicals
When the first signs of fire blight appear on a plant, treat it with chemicals. Copper-containing products are recommended; other products are ineffective. All affected parts of the tree are pruned and burned before treatment begins. In addition to the affected plant, nearby specimens are also treated.
Good results are achieved by using Energy, Previkur, and Skor together with antibiotics. This combination prevents microorganisms from multiplying within the wood. An additional benefit is improved immunity. Bordeaux mixture at a 1% concentration is also used to help sick plants.
Use of antibiotics
https://youtu.be/an6Fl1Sxw6k
When treating fire blight on pears, antibiotics provide one of the best results. However, for success, treatments must be regularly rotated. Treatment with antibiotic solutions begins in the spring. The first treatment is carried out before flowering, 8 to 10 days before bud break. During rainy weather, the treatment is repeated. The entire tree, including the trunk and the soil beneath the crown, is coated with the treatment solution.
Good results are achieved by treatment with the following agents:
- Streptomycin is an inexpensive but effective medication. The working solution is mixed from 5 liters of water and the contents of one bottle of the medication. Pear trees infested with fireweed are treated once every three weeks. The first treatment is carried out in May.
- Tetracycline is used only once a year. The solution is mixed with 2 tablets of the product and 3 liters of water. Treatment results are improved when combined with streptomycin. To maintain the effectiveness of the treatment, the tree crown is sprayed only in cloudy weather.
- During the growing season, pear trees are sprayed with gentamicin three times. A 5-day interval is maintained between treatments. The working solution is prepared by mixing 1 liter of water with the contents of a 2 ml ampoule of antibiotic.
- Ofloxacin is the most effective at killing the causative agent of fireweed. A solution is prepared by mixing one bucket of water and two tablets of the product. Spraying is performed in May or June.
- Ampicillin also produces good results. A solution is prepared from 5 liters of water and one 2 ml ampoule of the drug. The procedure is repeated every 15-20 days.
Application of Fitolavin
This preparation is intended for treatment of plants from various diseasesIt is used during the active growth, flowering, and fruit set stages. The solution is prepared by diluting 20 ml of Fitolavin in a bucket of water. It is most effective when applied at the end of flowering, along with Skor. During active growth, mix it with Acrobat, HOM, or Zineb. Fitolavin remains effective in all weather conditions.
Biological methods
Biological products contain substances that are lethal to the pathogen but safe for humans and pets. Gamair is one such product. It is diluted at a dose of 2 tablets per 1 liter of water. The tree is first sprayed in the spring at the bud break stage. Three more sprays are then performed at 7-day intervals.
As part of a comprehensive treatment for large numbers of affected areas, Fitosporin, a product containing Bacillus subtilis, is used. A solution is prepared by mixing 1 liter of water and 1.5 g of the product. To prevent disease, a lower concentration solution is used. For the same amount of powder, use 2 liters of water. The prepared solution is left for 2 hours before spraying the tree. The product poses no danger to humans, but bees may be poisoned by it. Therefore, Fitosporin is not used during the flowering period of fruit trees. A single treatment is sufficient for treating plants, but in rainy weather, repeat the treatment after 7 days.
Radical measures
When an infection appears in a large orchard with young fruit trees, drastic measures are taken. Trees with trunks blackened by fire blight are uprooted and burned. The area beneath them is cleared of weeds and sprayed with a copper sulfate solution for disinfection. The remaining trees are sprayed with antibiotic solutions, repeating the treatment every seven days. To prevent resistance, the treatments are changed each time.
On trees showing signs of fire blight, all infected parts are pruned and burned. Sharp, disinfected tools are used for this procedure. Shoots are cut back to capture a small portion of healthy tissue. The remaining pruning wounds are treated with an antibiotic solution. The area is then sealed with garden pitch.
Prevention
To reduce the risk of fire blight, preventative measures are used. First and foremost, choose the right seedlings. They are often infected even before planting. Therefore, avoid purchasing them from untrusted sources. Inspect the plants carefully before purchasing. Preference should be given to those that are free of external damage and have healthy, evenly colored bark.
It's best to buy pear varieties that are resistant to fire blight. This immunity applies to:
- Williams;
- Carmen;
- Maria;
- November.
In spring, a mandatory preventative measure is sanitary pruning of the tree crowns and spraying them with copper-containing solutions, such as Bordeaux mixture. All wounds are sealed with garden pitch. The bark of pear trees is also carefully inspected for the appearance of white droplets of exudate, the main sign of fire blight.
Another essential preventative measure is protection against insect pests. They weaken the plant's defenses. Parasites carry particles of exudate containing dangerous bacteria on their bodies. The crown of the tree is sprayed with insecticides or homemade folk remedies. The tree trunk area is also a must-have for insect control. To achieve this, weeds are removed promptly and the soil is irrigated with insecticide solutions in the fall.
Modern medications are used to treat fire blight. They increase the likelihood of eradicating the infection. The disease is dangerous for many fruit crops. Therefore, it is important to detect symptoms of infection early. For greater reliability, all preventative measures aimed at preventing infection are regularly performed.
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