fruit tree mulch in winter - propagating disease?

Hi everybody,
Over the summer I had mulch around the tree, at a distance of 10 inches from the trunk, in a circle. It is made up of hay, and partly of bark wood.
Now, I wanted to keep it over the winter too, to let it decompose in place. However, a friend of mine told me that the lots of fungi and bacteria from the fruit tree leaves will be able to overwinter in the mulch.
If I will remove the mulch, the cold will kill most of them.
But, in all permaculture tutorials that I read, it says that the mulch does lots of good to the tree, keeps it warm in winter and so on.
Should I remove the summer mulch and add a new mulch? and if so, when exactly? I don't want to add too early so that the disease attaches to my new mulch, but also not too late.
Can you give me some advice?

While we want all soil covered all the time, it is judicious to remove and replace things that simply lay on top of the soil, such as mulches around trees.
We keep a 3 foot wide mulch ring around all our fruit trees but it is changed out once leaf fall is over and then it is replaced just as the first buds begin to open.
By doing this we are disrupting the life cycle of any pathogen or insects that might have found "safe harbor" in the mulch rings.

The old mulch is recycled by going through the hot compost heap, this heating helps kill the pathogens/ insects and at the same time gives us great finished compost.

If we have a tree contract some disease that could be catastrophic, we trim it up and burn all the removed material far from where the trees are located.
When you do this you also need to be aware of wind direction since you don't want to end up accidently spreading the affliction to other trees.

Redhawk

Thank you for your response,
It seems logical to remove the summer mulch and replace it with a new one, indeed.
Here are a few issues that I see, though:
- I have living comfrey nearby the tree, too (inside the mulch ring), as part of the fruit tree guild, along with other plants. They are dead, or will be dead soon. Do I remove them too? They are nearest to the tree, so, actually, here will be the most pathogen preparing to overwinter. On all channels, when they say comfrey is good, they specify that when it dies, it gets incorporated into the soil, and helps the tree. Removing it, at the end of autumn, voids this argument.
- In lots of youtube videos, the chop&drop method is praised, saying you just chop something [black locust young branches in my case] and drop them near the fruit tree, then forget about them. It will be a great addition to the soil near your tree. Taking it away seems that it is not something those people do. They seem to imply that the branches would decompose there.
- During the summer, lots of good insects like spiders, but also other wild life, made a home inside the mulch. They also made preparations to winter in there. Taking it away to the compost bin seems a bit harsh on them and not the permaculture way.
EDIT: my mulch consists of hay.

In that case I would chop and drop the comfrey. The insects will flee the mulch as you are removing it. I take ours off in small clumps and all the good critters take their leave from the old straw and hay mulch.
I have also noticed that once I have the nice fresh straw and hay laid in place, they come back to the tree.
One thing to watch out for when you mulch trees is voles and moles, they can really harm your trees if they decide to make their homes in the mulch or use it as part of their tunnel system.

IN nature, most of the nutrients come to the soil via blow-downs or leaf fall/ branch fall. this woody material begins to decay and so nourishes the soil and thus the trees still standing.
The same should happen for your trees.

Chop and drop is the same as crimp rolling or pressing down, except you are severing the stalk from the root. It all becomes "mulch" for a while as it decomposes.

The thing to always remember is that nature works, always has and always will, but it can be harsh to plants at the same time.
If you are wanting a crop from a tree, you may need to alter the flow of nature at times, this is called disruption and is also a tool of nature.

Permaculture is supposed to be Observation of how nature works and then imitate the workings of nature With the idea of making a living from your crop(s) at the same time.  
It makes no sense to let diseases take over the trees you should be getting that crop from that is supposed to furnish you a living.

Lots of people forget that the whole purpose of Permanent Agriculture is to make a living by following the working methods of nature.
They get too caught up in "ideals" and end up not carrying the methodology to the intended end. Which is to make a living from the farm.

What we are doing on our farm is to follow the workings of nature so that we can harvest crops and make a living from our farm while doing as little "work" as possible.
The concept is Complete and Utter Neglect, but to do this you need to control water flow to allow the soil to hold as much as possible, create disruptions when needed to change the flow of progression so that our intended crop plants, bushes and trees become the dominant species.
It is a process, it takes time, and it allows natural soil building to occur once all the infrastructure is in place from following the natural progression.
This means that on a property you first handle the water, from there you start with what takes the longest time to mature to production age. This is usually trees.

Redhawk

This means that on a property you first handle the water

As Sepp Holzer stated: everything you grow is 70% water.  Once you have the water done, you're 70% finished.

Have you had issues with fungal disease?  If not, why the concern?  In nature, nobody rakes up the "mulch" and carefully carts it away.  It decomposes in place and the tree is all the better for it.  I'd say leave it in place and let it continue to do it's magic.

Below ground fungi is your friend.  If you are seeing mushrooms popping up around your trees after a hard rain, you should be very happy.  That's a sign of healthy soil and a healthy tree.

As for bacteria in your mulch, that's what you want.  Your trees will form symbiotic relationships with the microbes that they like, and will block those they don't.  That's why permaculture people love compost: it's the microbial injection that is most significant -- not the nutrients (although those are certainly welcome).  

I wouldn't pile mulch up against the trunk of the tree, but short of that, I would mulch right up to a couple of inches of the tree, and leave it there to decompose as it naturally does in winter.  To rake up and cart away good mulch that has spent the season breaking down is not just needless work, but it will be taking away carbon that has broken down and is feeding your soil fungal network.

My question was a general one, what to do with the summer mulch when winter approaches.
However, in my particular case, I do indeed have a fungal problem on my young cherry trees.
I identified it as "Coryneum blight" [Shot Hole]. see my pictures attached. [EDIT: A friend said it could also be bacterial: Xanthomonas pruni]
I also have attached a picture of my hay mulch around the tree, and what I have inside the mulch ring - near the base of the trunk [I see 4 white mushrooms, exactly as @Marco said that I should be happy about].
In the mulch picture, the cherry tree has no leaves, they all have fallen in august due to the disease, the leaves you see in the other photo are from another cherry tree.
The mulch idea was that if I pump up lots of micro life and nutrients from this mulch, the cherry tree would heal itself.

I live in orchard country , okanagan bc, there is an agricultural research station in town that sometimes does interesting work. they experimented with a papermache mulch and found that the tree roots grew closer to the surface under the mulch which caused some winter root damage in the winter. we also have a lot of rodent damage to fruit trees,girdling at the soil level. they live in the grass mulch that grows around the tree and thrown there when mowed. some times the orchardist does a kind of grafting called inarching to save the tree. that is to graft a small branch from the root to an area of cambium on the trunk this bypasses the girdeled area. to avoid this problem most orchardists in this area have gone to herbicides to kill the grass around the trunk area. this unfortunately poisons the soil the tree and the fruit. a win/lose.

Apparently this is dealing with small young trees. There fore removing all fallen leaves from the area and destroying them is not that labor intensive. Some of the spores may be harbored around the buds or crotches of the branches so a soap spray to wash them off and an oil spray to smother them might help. I would think of a wood chip mulch on top of the summer hay mulch would hold it down around the trunk so that it is not creating a fluffy habitat for rodents as it appears in the picture. Also a dense mulch will suppress any spores from getting back up to new leaves.
My pattern is to cut the comfrey when it is in bloom and therefore at maximum moisture and nutrients then cover that with the grass mowed with the scythe.  The comfrey then is then quickly incorporated into the soil by the organisms protected by the grass stems.