There are many stressors, which affect trees and put them under immense pressure. And even though one single issue can contribute to poor tree health, in most cases there are several causes at play, which impact its poor health and condition. 

It pays to be prepared with some knowledge on what the most common symptoms of issues on trees are. That way you can adequately take steps to ensure that the plants and trees affected are preserved and the issue is minimised. 

• Damage to the leaves – leaves are the natural diet for a variety of woodland creatures. With little damage on them, there is no immediate danger to the tree. There is hardly any single leaf without some leaf damage, which doesn’t prevent vigorous and healthy growth of the said tree. However, some pests and diseases can contribute to serious issues within the leaf or at its edges and maybe even the complete loss of leaves. One of the most widespread pests is horse chestnut leaf miner, which is a tiny insect that feeds on horse chestnut leaves. As a result, leaves acquire some brown colouring and see-through patches, which can damage the tree. Sawfly larvae also cause significant leaf damage. They are like caterpillars, which develop into flies, and not butterflies. Small trees are particularly vulnerable to them, as the insects can completely strip them. If damage occurs during the first flush, then the tree can recover. The Alder leaf beetle is another example of an insect that can affect tree leaves. It feeds on the leaves of the common alder and deciduous trees. 
  
  
• Wilting and yellow leaves – this is another sign of tree stress, the risk for which can be reduced by choosing the right tree for the site. The tree may have some sort of disease, be it a bacterial one or a fungi-based one. Paying attention to which trees are impacted is important because a lot of diseases are species-specific. For example, ash dieback impacts ash trees and Dutch elm disease is mostly present on older trees. Cherries are also prone to showing disease symptoms, with leaves looking wilted and brown. 
  
  
• Bleeding cankers – ‘bleeds’ on the trunks of trees are a sign of stress. There are many contributing factors, such as drought, pollution, freezing and waterlogging, in addition to some diseases. A common pathogen responsible for bleeds is the Phytophthora species, which is fungal-based. It blocks the water transport system of the tree, which in turn leads to bleeding cankers on the trunks. Bacteria can also be responsible for bleeding cankers. For example, Horse chestnut trees are often at risk from the bacterium Pseudomonas syringae. Small holes in the leaves often accompany the black patches of bark that appear on the trunk. A professional arborist may be the best bet for identifying the issue and providing a solution.
  
  

Sometimes, it is all about checking the location of the tree. Trees should be planted in the right space, or else they can struggle. Oak, yew, whitebeam, juniper and goat willow do well in slightly drier soil, whereas alder, willow and alder buckthorn do well in wetter conditions. If a tree is struggling, it may have to do with the moisture levels of the soil. If the soil is dry, then some watering is in order, though you need to be careful not to overwater the area. Water stress is often a cause for damage. 

© Treework Environmental Practice

Acute oak decline is a tree disease, which has impacted Europe severely several times in over 2 centuries. Currently, there is a version of this disease being observed in the UK, which has been monitored and examined for 20 years. The targets of this disease are trees over 50 years old, meaning that veteran oaks are at particular risk. 

The symptoms of acute oak decline include some of the following: 

• Crown thinning – sometimes it is a sudden occurrence, in other cases, it is gradual over 2 years. 
  
  
• Stem bleeding – the tree develops dark weeping patches. They may be less serious than they look, and can sometimes even heal if the tree recovers from that stressed state. 
  
  
• Tree stress – in such a state, a tree becomes more vulnerable to pests and diseases, which may appear on the tree. 
  
  
• Dark fluids – the dark fluids may seep through cracks in the bark, and run down the tree trunk. 
  
  

Several factors mostly determine the specifics of acute oak decline. The most important thing to remember is that the disease stresses out the trees. Things like waterlogging, pollution and sometimes drought are the environmental factors contributing to stressing the tree. Bacteria, fungi and insects can then further push an oak into decline. 

It bears mention that oak decline occurs in stressed trees. There are certain processes taking place then, such as the tree being unable to supply enough water, its crown becoming thin and it loses a certain amount of leaves. In response to drought, a tree will develop dark patches on the bark. The stress factors combine and then lead to low amounts of energy within the tree to compensate for the issue at hand. In this condition, it may be ill-prepared for cold months and not be able to manage a pest infestation as effectively. For trees pushed into decline like that, death may take place in the following years. 

Impact of acute oak decline 

Oak decline has been monitored for over 250 years. Germany has had an issue with this disease since the 1990s. In the UK, the oak decline has mostly struck in Wales and the southern shores of England. As it is an atypical disease, the spread of it is much lower. The same cannot be said for its environmental impact, however, especially in regards to the environmental conditions become more unpredictable. As a result, other tree species experience the same decline. 

The impact acute oak decline poses will increase, because environmental changes are ongoing still. Such a disease on trees will become more frequently surveyed, due to climate changes. Worse yet is the fact that the disease can cause the oak decline condition to be more severe. 

Here is what can be done about the acute oak decline 

Combating acute oak decline is not easy. One step in the right direction is to ensure more oaken trees are planted. More importantly, is planting them in an area that fosters their natural regenerative qualities. It is also important to do more research on the disease. Knowing what causes it and how it can be prevented and slow it down is very important. 

Good tree surveying is of utmost importance when it comes to acute oak decline. Having experts explore the trees in a given area and take notes of their condition can make all the difference in the world. Changing matters isn’t always possible, but it is essential to assess the situation early on. 

© Treework Environmental Practice

When it comes to dangers to UK trees, there are a lot of pests and diseases that qualify with the use of that word. It is important to monitor them and detect any issue early on so that it doesn’t lead to anything serious later on. Many pests and diseases can lead to very bad effects for trees if left rampant for too long. 

One of the best ways to control pests and diseases is to detect them early on through tree surveys. When arborists do that, they have a much better chance to deal with the condition of the tree, regardless of what it may be. There are several major pests and diseases that tree surveys can reveal: 

• Acute oak decline – this is a tree disease that affects many native oak trees. It is a condition that has been present within the UK for the past 20 years. Arborists note it mostly affects mature oaks that are over 50 years of age. Symptoms of the disease include crown thinning, vertical cracks of the bark seeping dark fluid, stem bleeding that gets more severe with time and the presence of more pests and other diseases attacking the tree, which is already weakened. Acute oak decline is mostly due to a combination of factors, like waterlogging, soil conditions, pollution and drought. These can all weaken a mature tree and then leave it more vulnerable to fungi, bacteria and pests. 
  
  
• Ash dieback – this disease, as evident from the name, targets trees of different ages. Of course, young, less mature trees are much more vulnerable, even though the symptoms are largely the same. They include dark patches of leaves, even present in the summer; early shedding; leaves and shoots die back; lesions at the areas where the trunk meets branches; epicormic growth – unusual growth under stress. The disease originates from Asia. And while Manchurian and Chinese ash trees have had more time to adapt and become less vulnerable to it, European ash trees have been way more susceptible to it. The reason is these trees did not evolve with the fungus that causes the disease and is much more vulnerable. 
  
  
• Asian and Citrus longhorn beetles – these are beetles that target broadleaf trees. There is a high risk of them being imported in the wood package. Damage from this kind of beetles is mostly present in the form of holes in the trunk. Adult specimens feed on foliage and sometimes cause this damage to the trunk. The beatles are also regarded for stripping young bark from shoots. 
  
  
• Dothistroma needle blight – this fungal disease creates opportunities for early needle drop. It is responsible for a lot of loss of yield in commercial forests and leads to the premature death of a lot of trees. It is particularly dangerous for Caledonian pine forests. The main symptoms of the disease manifest in June and July. At that time, arborists observe yellow spots on the needles of trees, which then go into the red. Needles shed a few weeks later after being infected. As a result, the branches get that ‘lion’s tail’ look with minor tufts of needle growth at the end. 
  
  
• Bronze birch borer – this is a beetle that gets its name from the metallic bronze colour that it has. It feeds on wood during the larval stages, which heavily impacts the tree capacity to intake nutrients and water. The symptoms of bronze birch borer infestation are dead leaf retention, leaf thinning and discolouration, swelling and welts of the bark. 

These diseases and pests are common enough that they need to be monitored and checked for through regular tree surveys, to minimise and prevent the damage from them. 

© Treework Environmental Practice