There were no bacterial burns of pears on the territory of our country before the beginning of the second decade of the 21st century. Until 2009, many gardeners were often confused at the sight of such a disease of pear. They did not know how to heal a tree, and what affects it. But now we will deal with this problem in more detail.
Disease description
Bacterial burn - a disease of fruit trees, which is widespread in Australia, USA, Canada, Japan and some European countries. 
In recent years, the disease has appeared in western Ukraine. Bacterial burn in most cases affects plants of the Rosaceae family. Stamps, shoots, leaves, roots, fruits are affected.
Important! If in the old garden almost all plants are infected with a bacterial burn, then planting a seedling in this place with almost 100% accuracy will lead to its infection.This disease affects the flowers in early spring. After that they wither, and then they dry up and remain on the tree until late autumn. Bacteria pass from the affected flowers to shoots and leaves. Thus, the whole pear is affected.
The disease is caused by bacteria from the genus Ervini "Erwinia amylovora". The birthplace of this disease is considered to be North America, from where bacteria have spread throughout the world. 
The greatest losses of fruit trees that were hit by a bacterial burn were recorded in Australia and New Zealand.
Soon the bacteria spread to Japan, where they began to actively damage pear trees. Japanese agronomists for a long time could not understand the cause of the disease of fruit trees, and only a few years later a certain scientist identified the cause of the disease - gram negative aerobic.
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The first signs of illness
Most often, this disease is detected during the flowering of pears. The flowers on the tree first wither, and then suddenly dry and turn black, and they do not fall off the branches for a long time. 
When the flowers are already affected, the bacteria begin to multiply throughout the tree, affecting the leaves, branches, bark, roots, etc. After this, the bark may become watery and acquire a greenish tint.
Leaves that are infected, dry out and turn dark brown. And the most interesting thing is that they remain on the branches throughout the growing season.
Did you know? For the first time, a bacterial burn was discovered in the USA at the end of the 18th century.As a rule, at first leaves turn black only on one shoot (they are twisted into a tube). Then the whole shoot is amazed, which dries out and dies very quickly. Soon the bacteria begin to infect other parts of the pear. In some cases, this leads to the complete destruction of the young tree.
Bacterial pear burn can be accurately determined in the laboratory. To do this, you need a dried shoot or a couple of dried leaves.The shoots are given to the quarantine services, which confirm or refute the presence of bacteria of the genus Ervini. For this are used such methods: Clement reaction, Gram stain or molecular methods.
The causes of bacterial burn
The main cause of bacterial burn is considered to be wasps. During the growing season, these insects feed on exudate (mucous fluid).
This fluid is excreted by a pear tree in places that are affected by bacteria. As a result, wasps spread millions of bacterial sticks to other trees. This is especially dangerous when a large number of young pear seedlings grow in the garden.
This disease can also spread in the root zone (in cases where the trees in the garden grow close to each other). Gardeners often think that the roots affect ordinary root rot, so they ignore a dangerous disease. 
Sometimes droplets of amber or milky color can be observed on the affected leaves and pear flowers. These droplets contain several million bacterial sticks that spread to other trees through flies and other insects.
The cause of infection with a bacterial burn can be a strong wind, rain or fog. Bad weather conditions are capable of spreading droplets filled with bacteria to the flowers and leaves of other plants.
Disease treatment
If you notice signs of a bacterial burn on your pear, then, first of all, you need to remove the blackened shoots and leaves, and then burn them. The affected branches are burned in order to completely destroy all the bacteria on it (they die at a temperature above 43.7º C).
Important! If you are engaged in beekeeping, then the hive should be placed away from pear seedlings.The affected area must be disinfected with copper oxide or copper sulphate. If the seedling was completely killed by a bacterial burn, then in its place it is impossible to plant new trees for the next two years.
Bacterial pear burn can be treated with antibiotics. Gardeners from Western European countries have been using antibiotics for a long time, since they do not see much of the effect of copper-based products. Among antibiotics, terramycin and streptomycin are very popular.Do not be afraid to use these drugs. For example, streptomycin has not been used by doctors for a long time. Human pathological bacteria have long since developed immunity to this drug, therefore, it is harmless to the body.
But for bacteria that infect trees, in particular for Erwinia amylovoraThis antibiotic is a deadly weapon. Apply it like this: one ampoule per 5 liters of water; such a solution is enough to sprinkle ten pear seedlings. 
But it is not necessary to use streptomycin for more than 2 years in a row. After some time, the bacteria may develop immunity to it, and they will cease to die from the action of the antibiotic. In this case, tetracycline can be used. It should be diluted as streptomycin.
Did you know? Bacteria that cause pear burn begin to develop rapidly at temperatures above 18º C.Bacterial pear burn requires proper treatment in the very initial stages. Otherwise, the disease can affect nearby trees.
Prevention
If a pear bacterial burn is detected in a timely manner, the tree can be cured without critical consequences. Prevention in this case plays a very important role.
Competent selection of seedlings
When choosing pear seedlings, you need to pay attention to the branches, leaves, trunks and roots. The trunks should be smooth, and the twigs are healthy (without spots, wounds, flows and juice).
If there are blackened leaves on the tree, then this is the first sign of seedling disease. Roots must be healthy (half-lignified, without rot). 
It is best to buy grafted seedlings. They are characterized by good drought tolerance and good immunity to some diseases.
Garden Pest Control
When a pear blooms, it must be treated with an antibacterial agent. To do this, use Bordeaux liquid, which has a characteristic bluish color. 
To prepare this mixture you will need: 10 liters of water, 100 g of copper sulphate, a little fresh lime and two five-liter vessels (glass, clay or wood). In one of the vessels, you need to mix 5 liters of water and vitriol, and in the other, lime and the rest of the water.
Use the following insecticides against pests in the garden: Spark Double Effect, Decis, Nemabact, Nurell D, Actofit, Kinmiks, Omayt, Calypso, Bitoxibacillin, Actellic , "Malathion", "Inta-vir".Next, the liquid with vitriol should be very thin stream poured into the solution of lime. It was vitriol into liquid, and not vice versa! The result should be a light blue liquid.
Important! Bordeaux liquid can be replaced by fungicides. Copper is also present in their composition.The main point in the preparation of Bordeaux liquid: do not overdo it with copper sulphate, otherwise there is a risk of burning flowers.
To check the mixture you need a regular nail. It must be dipped in liquid. If you see red bloom on it, it means that there is a lot of vitriol in solution, then you need to adjust the concentration of the mixture by adding lime.When the mixture is properly prepared, you can begin to spray pear flowers. On average, 10 liters of solution is enough for 10 seedlings.
It is necessary to take into account the fact that with the frequent processing of a pear with chemicals, bacteria develop immunity. They begin to mutate and subsequently cease to die upon contact with these substances. 
Rodent control in the garden also reduces the risk of bacterial burns on the pear. Mice and rats that eat the roots of a tree can tolerate harmful bacteria.
For pear seedlings you can use immunity stimulants: immunocytophyte and zirconSimulators provoke defensive reactions of the tree and help in the fight against pathological bacteria.
Disinfection of garden tools
Many gardeners use common medical alcohol to disinfect garden tools. For example, if you took a spade from a neighbor and rubbed it with alcohol, you can be sure that the bacteria that cause the pear burn have completely died.
In the USSR, substances that contained chlorine or kerosene were used to disinfect garden tools. It is possible to disinfect a shovel, glanders or saw with potassium permanganate, as well as with copper or iron vitriol. To do this, the tool is dipped into the solution for some time, and then wiped with a clean cloth.
Saw or hacksaw can be processed with fire. Then the teeth of the cutting element are completely cleaned of all pathological microorganisms.
Did you know? Bordeaux liquid is named after the French city of Bordeaux. The French botanist Pierre Marie Alexis Millyard invented this mixture.Today, many gardeners use domestic disinfectant pharmaceutical. The active substance of this drug is a water-soluble iodine complex.
This tool can disinfect any tool, and even the soil or greenhouses.
Finally I would like to say: if you saw the blackened leaves on your pear, then immediately cut and burn them, and disinfect the instrument by any method listed above.
A timely fight against a bacterial burn will prevent your plant from dying.
