What is the ELM tree?

Elm tree is a majestic tree that once lined the streets of many American and European cities. He suffered from a debilitating disease that killed most of the trees on these continents. Durable varieties are now kept and hope that these majestic trees will again be merciful streets, as it was before. From the 17th century to the beginning of the 20th century, the ELM trees were very popular along the streets in Europe and North America. They could tolerate air pollution and their leaves decompose rapidly. The trees were also useful for farmers as a shadow for livestock and protection from winds and storms. The branches were used to feed animals.

In the 20th century, the trees came under the attack of the fungal disease ELM known as Dutch disease ELM , which is carried by a bark of beetles. There were two waves of this disease. The first, lasting until the age of 40. The 20th century was not very serious. At the end of 1960s, however, a tribe appeared, which was three times more fatal. Has fired most Elms in most areas in which the fifters wereTuned, with the exception of China and Australia.

Breed programs

Resistance programs have been taking place for decades. In the 1970s it was shown that the trees that were supposed to be resistant to the disease were not. Subsequent efforts for breeding have made a new harvest of resistant lines, but previous failures have sour some people in planting these contemporary durable trees. So far, however, these new lines seem to be held.

The most common ELM tree in North America was American Elm or u. American. It grows rapidly, is resistant to wind damage, requires small pruning and is adapted to a wide range of soils and climate. Elm Street is the most common name of the street in the United States due to its one -off prevalence. Trees that are isolated, such as Zafarma, are more likely to survive without closing the Dutch ELM disease.

This deciduous tree can grow to 100 ft (30.5 m) with widthIt can be even bigger. Trunks usually reach up to seven ft (2.1 m) wide. Before the leaves appear, the trees bloom with inconspicuous small flowers, followed by seedpods, which are eaten by wild animals and birds. The leaves of the ELM tree have a rough surface and are 3 to 6 inches (7.6 to 15.2 cm), with serrated edges. The bark of the tree is gray -brown and as the tree matures, it rotates to the ashes.

In the United States, the American tree ELM is resistant to 2 to 9 planting. This tree is still planted by people who are willing to be vigilant about the monitoring of the Dutch ELM disease. The cultivars with the greatest resistance to this disease are the Forge valley and new varieties of harmony. Some people left when they tried to grow American elm and instead grown Chinese or lace, u. Parvifolia . The Chinese elm, although it is resistant to the ELM disease, is not a good tree of shadow.

The

control of the Dutch ELM disease relies strongly on hygiene measures. Weakened or dead trees and protocols wouldLy to be removed and destroyed. Sometimes the disease can be eliminated by pruning infected branches and twigs. Healthy trees can be sprayed with insecticide in winter and spring to kill beetles that spread the sponge. However, these measures were only partially effective.

the roots of nearby trees can sometimes connect. Killing these grafts with chemicals can limit the sponge to a specific tree. A promising new treatment is to help a suitcase or roots with a systemic fungicide that directly attacks the sponge. This technique was used to treat the patients' trees, but is not always reliable. There is currently research into the use of viruses that attack the sponge to control the Dutch ELM disease.

Elm trees should be planted 40 to 50 ft (12.2 to 15.3 m) from other trees and at least 15 to 20 ft (4.6 t (4.6 to 6.1 m) far from the houses. They prefer full sun and regular watering in the soil with good drainage.They spread out, should dig deeper around the edges of the holes. Young trees can be transplanted early in spring or autumn when they are between 4 and 7 ft (1.2 and 2.1 m) high.

There are some disadvantages for planting ELM trees. The roots grow near the surface and can disrupt mowing or lift sidewalks. Trees require pruning and producing quite a little litter. Many people feel beauty and shadow produced by these trees, but more than replace any negative attributes. Hopefully ELM trees will again be part of the city landscape in Europe and North America.