Dutch Elm Disease (DED) is considered one of the most destructive diseases of shade trees in North America, and the cause of the most massive epidemic of tree diseases ever.
If you have even the slightest suspicion that your trees are at risk, read this material carefully. We will discuss DED basics, detection, treatment and protection from the disease.
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Dutch Elm Disease: History and Basics
All varieties of elms native to North America are susceptible to DED, but the most vulnerable is the North American elm, Ulmus americana.
Unpretentious and tolerant of all environments, the North American Elm has been one of the most widespread shade trees in the United States.
The first occurrence of DED disease was noted in 1919 in the Netherlands, in a Dutch country (this is actually why it’s so named). The disease spread rapidly in Europe and by 1934 was found in most European countries.
Dutch elm disease was first found in the United States of America in the River in 1930 and also near the port of New York in 1933. The 1st proven DED incident in Oklahoma was found in 1961. The disease is widespread in the amber mid-US State and also existed established in the sunset up to the Woodward locality.
How Can You Discover DED Treatment
The first signs that the Dutch disease has struck the elm is the condition of its leaves. They begin to curl and dry up. Then there is drying and loss of strength of the elm bark beetles of the tree’s vascular system.
The fungal disease affecting an elm can proceed rapidly or slowly. The course of the disease directly depends on how quickly the blockage of the vessels of the diseased trees occurs, a gum-like mass that is formed as a result of the vital activity of the fungus.
The rapid course of the disease causes sudden shedding of twisted leaves, damage to bark, and as a result, elm’s vascular system dies within a year. Such a tree has to be removed, and the sooner the better. Leaving post The Homeowner’s Guide to Tree Removal: Cutting Down a Tree in Sections (2023) here; it may be helpful, alas.
The slow or chronic development of the disease can last several years. During which the foliage of elms has a yellowish tint, not only the leaves, but also the branches of the Siberian elm tree with grafted roots dry in large quantities, which ultimately also leads to death.
It should be noted that this disease is very dangerous because, firstly, it is almost impossible to detect in its early stages, secondly, it quickly spreads to elm plantings over large areas, and thirdly, it is not treatable.
Trees that have been exposed to Dutch disease
Without exception, all local elm varieties are susceptible to DED. This includes:
- American Elm (Ulmus americana)
- Many species of American elm possess the most significant stability to the disease and also have every chance of being cured by infection. They are often traded as well as constant to DED.
- Red or slippery elm (U. rubra)
- Rock elm (U. thomasii)
- Asian elms have the greatest degree of stability to Dutch elm disease and also have every chance of not expressing signs of the disease in any way.
- Chinese elm (U. parvifolia) is not hardy in Minnesota. This wood is used in the maternal property in DED wood beneath stable hybrids.
- Japanese elm (U. davidiana var. japonica)
- Siberian elm (U. pumila) – Single trees are very different according to stability to Dutch elm disease. Many wither and also die when infected, others endure infection for many years.
- Scientists and breeders have bred a number of mixed elms that are stable or tolerant to Dutch elm disease. Detailed data on the types of elm, which grow well in Minnesota, can be found in the publication “Dutch elm disease-resistant elm trees“.
How Does This Incurable Disease Progress?
The fungus (ophiostoma) was identified in the early 20th century in Holland, hence the name of the disease. However, it is believed that the fungus was brought to Holland from East Asia, then spread to Europe and North America.
Graphiosis disease is one of the most dangerous diseases of elm breeds, which prevents their growth. It is widely distributed in natural and artificial plantings of steppe and forest-steppe zones. The disease affects elms of all ages, especially strongly at the age of 10-40 years.
Both in Europe and in America today, the Dutch elm disease causes mass death of elms in forested areas, and in case of failure to take urgent measures, it threatens to completely destroy the elm population.
The first signs of the disease can be seen at the very top of the tree. The tree’s upper branches wither, the leaves turn yellow and curl up. The yellow stunted branches can be seen from afar like a flag.
Initially, pruning the infected branches may help. If you fear for other healthy elms on your property, be quick and decisive.
Since the branches are quite high, it is worth turning to professionals. There are some tips here to help: How to negotiate tree removal company: Simple steps to agreement.
How can plants get infected?
But the fungal spores disease itself would not have such sad consequences if the carriers of the fungus had not been involved with beetle feeding.
This is a small insect (elm tree beeetles) 3-5 mm in size, which clings to the bark of weakened trees, especially in shaded dense plantings, where no forestry measures are carried out. Elm sapwood is a classic elm bark beetles with lay eggs of susceptible trees that feed in the axils of elm branches, and additionally reward it with a dangerous ded fungus into root graft.
Sometimes dried spores are carried by the wind or spread together with diseased wood. In this case, the infection of a new susceptible trees occurs through fresh damage.
The disease occurs in an acute or chronic form with plug like structures. If the leaves are twisted on the elm bark beetles is drying, then this is the first sign of the Dutch elm disease. There is a lesion of the conductive systems of the entire tree with infected branches, in which the vessels are clogged with a gum-like mass.
If during this period you consider a cut of a earliest stages tree with infected branches, you can see the affected vessels in the form of brown spots on the wood with valley forge, as well as continuous and intermittent rings. In addition to directly clogging the vessels, the fungus secretes toxins, which are also the cause of the withering of the brown leaves tree with dying branches or root system.
And, if the crown of the elm is withered, try to study the cut of the branch or root graft. Dutch disease is both the cause of the drying of the leaves wilt on the elm with brown streaking, and the cause of the drying of the bark on affected branches, and the cause of the death of the whole infected elms tree with root system in other trees.
ELM bark beetles
Local elm bark beetle (Hylurgopinus rufipes), the smallest pan-European native elm bark beetle (Scolytus multistriatus) as well as the striped native elm bark beetle (S. schevyrewi) have every chance to withstand the Dutch elm disease mushroom discussions together with the 1st log in the other intact bark on one or more branches.
The older females of absolutely all 3 types of elm bark beetles delay the testicles near the peel of recently killed or dying healthy elm trees or in firewood or logs together with a thoroughly fixed peel.
The larvae feed the intact bark on the inner peel and sapwood of the log, forming galleries and tunnels during the adult beetles feeding period.
If the wood is infected or Dutch elm disease was killed, the DED fungus (Dutch elm disease) will be in the wood. Sticky discussions of the DED fungus will begin to form in tunnels as well as galleries formed by elm bark beetle.
If the newest proselytes arise as well as the older individuals from infected elms, they carry the fungus into their own torsos as well as into theirs.
Not so long ago, the proselytes that have arisen rush into strong elm trees with root grafts in order to eat asiatic elms one tree.
If the proselytes gnaw through the peel, the discussions in the banded elm bark beetle body are killed in the course. These discussions stimulate the latest Dutch elm disease infections.
Small bark beetles of euro elm and bark beetles of striped elm feed at intervals among the branches of strong healthy trees. For this reason, the latest infections by inner bark can be traced in small twigs.
District elm bark beetles feed on the largest branches 2-10 inches in diameter. These infections appear in key or secondary branches in one tree.
A number of banded elm bark beetle have every chance to eat in 1 log, which leads to numerous infections spreading according to the whole crown on host tree.
In some cases, the district bark beetles of infected elm trees record Dutch elm disease in the trunk branches of the log, if they dig holes, in order to form a role for the purpose of wintering.
Movement within the ELM trees
Once in the vascular concept of elm trees with root grafts, the discussions of the fungus sweep along according to the log along with the hail of water.
The wood will form cork-like textures, called tyloses, in the cells of the venous log concept, transporting water, in an effort to stop the progress of the fungus according to the log.
Unfortunately, sensitive infected tree with elm bark beetle do not make tiloses in any way quite rapidly in order to block the fungus. Instead of this, this untimely safety response is capable of provoking drying as well as drying of the crown.
Movement an elm bark beetle through root grafts
- The DED fungus with elm bark beetle will form a filamentous layer, called mycelium, which increases downwards according to the orientation to the large-root concept.
- With the help of infected trees form root grafts, the fungus is often eager to achieve a large-root concept during the 1st season, in which someone is infected.
- The surrounding elm trees form root grafts, which make it possible here as well as nourishing preparations to flow from the 1st log to another.
- Vaccinations are usually carried out among neighboring trees of this type, after all.
- In some cases, root grafts appear among neighboring trees of various types.
- The DED fungus (Dutch elm disease) is able to move according to root grafts and also destroy the surrounding trees.
- An infectious disease that occurs through a large-root xenograft often expands very rapidly according to the log.
What Are the Ways to Treat This Disease?
Since it is impossible to cure infected tree with root grafts, then you need to try to protect them. To do this, you need:
- regularly inspect the infected tree;
- practice mixed group planting together with elms that are resistant to Dutch elm disease;
- timely remove and burn all affected and simply damaged parts of infected trees;
- treat healthy trees with fungicidal and insecticidal preparations to combat the vector of the controlling Dutch elm disease fungus;
- if the disease is detected at an early stage, you can try to save the destructive tree diseases by injecting fungicidal drugs with a syringe into the lower part of the trunk with dying branches
- invasive species.
Answering the question about, Dutch elm disease treatment, we want to note the following. In order to protect individual healthy trees in parks directly from fungal disease, as a result of which vascular blockage occurs, individual destructive shade tree diseases is injected with a systemic fungicide into the lower part of the trunk with infected wood.
In forest plantations, supervision is carried out annually in July — September, selective or continuous sanitary logging is carried out when a disease is detected, timely removal and destruction of felling residues is necessary, stumps are subjected to antiseptic treatment.
It is recommended to create mixed plantings, use healthy planting material taken from resistant species, breeding forms or individual elm specimens.