What´s happening with birches?

In the last 10 years, there are lot of problems with birches (Betula pendula), what's happening?

Thin canopy of Betula pendula. Photo: Ravel Reiljan

Who/what? 
It may be the fault of the fungal pathogen Neonectria sp. or oomycete Phytophthora sp. - rather in combination.
May be easily confused with Taphrina betulina, but the symptoms are much more widespread and the consequences are more serious.

Deformations in the trunk. Photo: Ravel Reiljan

Symptoms?
Hollows, bumps, cracks and other anomalies, thinned crown, smaller leaves than normal, dried tree branches, "bellies", lot of dead shoots, fractures of larger branches, "bumps" in the root collar area (up to 1,5 meters), leakings and often "life belts" in the same area, plus the round (not eccentric) shape of the wind roots - besides, I have also seen the presence of hydrotropy on sick trees.

Deformed Betula pendula. Photo: Ravel Reiljan

Why/how?
Hypothesis - In 2005, Pärnu (a small town in Estonia) was hit by a strong January storm, resulting flooding a part of town with a seawater.
Saltwatered dense soil could be the reason why the pathogens started to act.

Most of Phytophthora species are attacking a root systems and the root collar area - so it is logical that the primary symptoms appeared in the crowns of trees about 5-6 years after the flood, ie in 2010/11.

Bleeding area above the root collar. Photo: Ravel Reiljan

Is it wise to cut the bad branches out of the crown?
I have noticed that cutting off the still living branches deepens/accelerates the degeneration, so it would be advisable to cut off only dead branches.

The biggest problem is raising the crown - this should not be done if possible - because of H/D factor, inhibition of diameter growth, water and nutrient transport.
 

Broken Betula branch. Photo: Ravel Reiljan

What to do?
Trees try to deal with their own problems itself - by reducing their crown in the case of extensive root damage, and also by drying out branches.

The development of the pathogens is individual for each tree, which is why they need to be reviewed regularly and act accordingly.

In the urban environment, there is a serious risk of breaking/rupturing larger branches.
In case of Betula pendula - the biggest risk of breaking branches is in the late autumn after the plant has drained the crown of juice - it is that we lose the elasticity - which is replaced by brittleness.

So, unfortunately, it is so that in the next 15 years, many-many birches will have to be cut and replaced with more appropriate species in area.



Source: Urbandendro
http://ravelreiljan.blogspot.com/

Why do elms dry and die?

On June 16, 1940, there were published an article in the Estonian newspaper "Postimees" titled "Why do our elms dry?".
This article described the invasive fungal disease - Duch elm disease (DED), (Ophiostoma ulmi - with slower development or more aggressive form Ophiostoma novo-ulmi) - and then it was written: "The disease occurs massively, spreads rapidly, and a large part of our elms is already caught or even destroyed".

History seems to be repeated and Estonia has been hit again by a large variety of outbreaks.
Over the country, you can often encounter sick trees at different stages - in parks, green spaces, gardens, and so on.


What are the symptoms of this fungal disease?

Typically, the disease begins with one or more twigs on the tree, with sharp wilting and drying - whereby the dried and kinky leaves remain on the tree.

The first sign of danger - dried branches in the crown. Photo: Ravel Reiljan

Then, the whole crown will dry out, which can take younger trees only a few weeks and older trees from a couple of months to several years.

Dying elm tree. Photo: Ravel Reiljan

Finally the whole tree dries and dies.

Dead elm tree. Photo: Ravel Reiljan

Relatively firmly, you can determine the disease by cutting off the sick branch and looking at its diagonal section when the first signs of the disease appear - if there is a dark streak near that outer edge, you can be quite convinced that this is Dutch elm disease (DED).
Trunk has often open bark (although not at the beginning of the infection), as if the tree were covered with a open coat.
However, no open bark is present on all sick trees, but a dark streak is always present.

Dark streak is easily visible. Photo: Ravel Reiljan

How to prevent?
Do not know yet.

What to do?
Basically, we can't do anything for the sick tree.
What can be done is to prevent the spread of the disease.
To do this, it is necessary to constantly monitor the state of the tree, and if it is seen that the signs are spreading fast and the drying of the tree seems to be certain, the tree should be cut.

Is this enough?
No.
The following is important:

1. The tools used for cutting (generally saws) should be disinfected (with antiseptic) after finishing work.

2. Cutting residues - should be burned immediately or -

3. When storing - if you want to make firewood for yourself - the logs should be peeled off and the bark should be burnt immediately (the bark must be peeled because of the bark beetles that spreads the fungal infection).


If you follow these steps, you have already done a lot for other elms.


Source: author's personal notes and observations.
Also consulted by Liina Jürisoo, an Estonian University of Life Sciences doctoral student.
http://ravelreiljan.blogspot.com/ 

Few details for the spruce hedge owners

Spruce hedges (Picea abies) are quite widespread in Estonia, and although they are mainly grown in non-urban areas, they are fortunately also used in settlements.
These hedges are a relatively sensible and low-maintenance solution in our conditions, but there are still some important details to pay attention to for hedge owners.

Common spruce (Picea abies) hedge in Estonia. Photo: Ravel Reiljan

1. When you start a planting, the plants would be worth buying from a nursery where the seeds were selected from high-quality trees and grown under the same conditions. By collecting plants from forest, we can usually get specimens with quite different growth conditions and it may happen that instead of a uniform hedge we have a hedge where some plants grow faster than others and some plants have a narrower needles than others. In addition, the plant color and dimension may also vary in some places.
    

2. After planting, it should be observed that grass will not grow under the crown of young plants.
   Instead of mowing (there is threat to damage the cambium) or plucking (always risking damage to delicate roots), it would be best to use protector rings or plastic discs with a hole in the middle. Such disks are usually sold in forestry businesses, but can also be produced by yourself. 
   They should be used for at least a couple of years until the plants are tall enough.
   
   
3. Many places where a young spruce hedge grows are often easily accessible to a variety of animals that are threatening plants during the winter time. To avoid this problem, it is perhaps the easiest and most reliable way to use a repellent - such as Cervacol (in Estonia) - in this situation, you should treat plants every late autumn (shoots and tops) for some years.
   
   
4. After a couple of years, however, it is not advisable to let the grass grow under the spruce trees - under the young trees it grows easily and the lower branches may die - so, whenever possible, the crowns area should always be kept clean.
   But mowing must be done very carefully in such places - the main damage that I have noticed to young spruce hedges is related to mowing damage. When approaching trees with a trimmer, you should always make sure that the trimmer's head protector is always towards to tree trunk, in which case there is no risk that the cambium will be damaged.
    
5. Usually alien species tend to grow in young spruce hedges - they should be picked out in the first or second year if possible - later problems may arise.
   
   
6. Trimming is actually a separate topic because everything depends on the growth stage and the type of hedge you want. 
   But - three basic things to remember: 
   a) In Estonia, it is not reasonable to perform trimming in the winter season.
   b) Topping before the growth you need, is not a reasonable.
   c) When you trimming the hedge from top, the hedge must be cleaned from cutting residues.
   
   
7. Occasionally it happens that the top of some spruces can be damaged or is shorter then side shoots. In such situation, a competitors should be removed or shorten.

   
   
8. There is common problem - where one or more plants have started to dry out in hedge.
   If something like that happens, you should react quickly because it may be a fungus called Heterobasidion parviporum (the rate of spread can be up to 2 meters per year through the infected root system).
   
   How do you understand if this is Heterobasidion? 
   When all the plants have been bought in one place and only one or a few of them have started to dry, it can be assumed that the small seedlings have not been infected in the nursery. In this case, you should definitely look at the dried plants for more details - are there any signs of mechanical damage in the root collar area? Or is it easy to see a resin or cracks on the strain?
   
   If any of these things occur on the plant, there is reason to be worried. In this case, when it is seen that the plant dies - it should be gently pulled out and burn it with the root system, if possible. In the case of a young hedge, it's easy, the older plants case you should consult with specialist, there are some different possibilities.
   
   In such a place, the new plant should not be planted before a minimum of two years.

Heterobasidion parviporum is acting. Photo: Ravel Reiljan

Heterobasidion parviporum fungal body in stump. Photo: Ravel Reiljan

Source: Urbandendro
http://ravelreiljan.blogspot.com/

About dendrological evaluations and maintenance plans in Estonia

Most local governments in Estonia occasionally orders a dendrological assessment, maintenance plan, or expert assessment from a some company for evaluation some parks or other green areas.

Unfortunately, we can say that some of these "evaluations" are almost or absolutely useless for a later field works.  

For example, let's look at the following situation: let's say that a local government has ordered a maintenance plan for some parks - so - a procurement is organized, a winner is selected and a job is commissioned.
Work starts - a professional or a professionals army will be coming and investigating - and finally the completed work will be sent to the local government.  

The job is serious, its volume is tens of pages for one park - there is a lot of accurate information about the condition of the trees and also the maintenance - we can think, but, unfortunately, browsing the finished work, we have to be surprised to find that most of the dozens of pages are just background information - the history of the park, a lot of beautiful pictures, general talk, all kinds of descriptions and everything else - the only thing that is not there - is the exact description of the health conditions of the trees and the exact description of the work to be done.

Let's take a couple of examples - I have found the following keywords in the sections of health status and maintenance descriptions, for example, when I have flipped through different expert works:
"low tree", "young, beautiful tree", "lesion", "fungal body", "take away some branches", "shell damage", "strain damage", "thickener", "hollow", "strain hole", "dry branches", etc.

What does this information gives to the worker who need to work according to this plan? How company performs the necessary actions based on this information?
And then - the job goes again to the archive, and the company that works on the site has to figure it out and decide how and what to do...

For such work, it could be said that it is a waste of tax money - the local government should not accept such works and pay for it.
There is no need for a specialist to carry out such work, such descriptions may be given by a person who does not particularly know a lot about the evaluation or the mechanics of trees.

In reality, it is not difficult to describe the condition of the tree and the risk factor (to some extent) with simple visible things - you just need to know the way of life of trees and a some of tree mechanics.

For example, there is a widespread perception (in Estonia) that a tree with hollow is dangerous and needs to be cut - this is rarely the case - we can say quite firmly that certain hollow trees are no less dangerous than any healthy tree.
In addition - fungal fruiting bodies in tree trunk - what does this knowledge gives us?
Nothing, if we do not know the type of fungi, the type of rot is caused, and how large is the hollow or decay it has already made.
Also - is a leaning tree dangerous? Many think it is - but there are some rules that can make a leaned tree more stable than an adjacent straight-growing tree.
Etc, etc.


So - what to do and how to improve the situation?
   
First of all, local government officials who decide on the maintenance, also over life and death of trees, but feel at some point uncertainty, should get to know their area better - so they can demand more precise work.
To do this, they can always turn to the local arborist, the Estonian Arboriculture Society or the Arborist Chamber - if necessary, all of these are believed to be ready to organize the relevant training sessions, study days, or just consult if needed.
Don't be afraid to ask - asking never shows stupidity or inexperience - it shows a person's interest and caring - it shows that the official is worried and wants to get the best deal for our environment.
And the questioning officer is one thing which makes the arborist proud.

Secondly, the arboriculture organizations, federations and schools should think - maybe we can be able to create a simple training center for local governments - the environment is, however, our common concern and every specialist should give a share to their social contribution.

Thirdly, companies that estimates parks or green areas, could involve an external specialist (e.g. arborist) to assess the health status of trees and describe maintenance activities. I believe that the situation will improve considerably.

Fourth, an official who prepares a procurement contract could set out specific things that are not recommended for the job (history, background descriptions - if it is already done sooner - and usually it has, several times, etc.) at the start of the procurement and which are desired (health assessment of the trees, precise care instructions, perspectives, problematic places - real solutions).

Source: Urbandendro
http://ravelreiljan.blogspot.com/

Blackcurrant gall mite is attacking - what to do?

Sometimes in the summertime happens that the blackcurrant shrubs suddenly do not seem as healthy as they should be, also in the harvest time there are less berries as sooner years.

It can be caused by different pests or diseases, but it is most likely the result of black currant gall mite action.
In the Estonian environment, the black currant gall mite is mainly damaging black- and lesser red- or white currant, also very rarely gooseberry shrubs.

How do I know that it is gall mite? 

During the summer period, the damaged shrubs tends to be sickly and partially wretched. At the time of harvesting, the amount of berries is usually much smaller than in the previous harvest years. There are also some branches with old buds from the previous year.

The most convenient and secure is to determine the existence of pests in the spring (in Estonia the first half of March). Then look carefully at your shrubs - if there are two varieties of buds - one type rounded and the other with a sharp tip - the thing is, to put it mildly, dubious.

Buds where mites are in action. Photo: Ravel Reiljan

In this case, take a few round buds, look for a hard base and cut the buds with a thin piece of steel. Then use modern technology - (with naked eye you can't see nothing, because the size of the mites is only about 0,2mm) for example, a magnification glass or a mobile/camera macro.

There is no need to look for those characters very hard, because there may be a whole group, ie mite(s), eggs, larvae etc, in one bud. Moreover, the population of a single bud can be very large, reaching thousands of individuals - so if you have a handy tool with sufficient magnification, you will see them immediately (they have fun in bud and they fuss around).

Inside the bud - eating. Photo: Ravel Reiljan

What to do?
 

What if the diagnosis is confirmed?

Then you have to act - if the shrub is too tight, it has overgrown or drooping branches, then first thin your shrub to a reasonable extent, then start to pin out the round buds. Collect them and burn them immediately (not suitable for composting) with expelled branches - if you don't, the shrubs will soon be destroyed because the source of infection remains.

 

If about half of all buds remain in the shrub, the shrub can usually cope with the situation itself and begin to recover quietly next season (this activity must be repeated every year until the problem is off the agenda).

But if the bush has practically all buds inhabited, the story is more complicated - in this case, the situation should always be based on - how long have the symptoms lasted? Are there few or many shrubs damaged? Is there a risk of major financial damage

In this case, the use of a systemic poison or destruction of shrubs may be considered. You should now consult a professional.

When it is best time for pinning buds or thinning shrubs?

The most convenient time for this is actually the first half of March (in Estonia), because you can then easily make the difference of the good and bad buds, and this time is also well suited for thinning shrubs.

What more to notice?

A very important aspect - always disinfect the cutting tools before going to a new shrub and after cutting the last shrub.
Use antiseptics for this purpose (vodka is not suitable).

Why do they come to my plant?

If we are dealing with a shrub grown from good material that has been properly nursed in a nursery and then properly planted in a growing site/soil and has been properly maintained in the garden (agrotechnics), then this question is really justified.

However, if any link in this sequence is so weak that the plant cannot handle it quickly, it is not good - the stressed plant is susceptible to various malignancies and diseases, and then the serious problems are no longer far away.

So - the presence of mites in your plant is usually (in the case of mites, often the question is bad reproductive material) is a plant emergency call for you as a caregiver - something is wrong with the plant and it needs your urgent help.

How to help?

In this article I wouldn't better deal with it because the subject is more sizable and requires a separate approach - however, some of the risk factors I have noticed are: untreated (too tight, aged) shrubs, autumn leaf and placing apples under the shrub, ash throwing under the shrub and excess soil acidity. If you are attentive to these things, there is already a high probability that your shrubs will be healthier and stronger.

Source: Urbandendro
http://ravelreiljan.blogspot.com/