Question about much, maybe not pc

[oldugly]

I got a question about the values of mulching. I agree with everyone here in the values of regulating temperature, helping to hold in moisture, and many other benefits about mulching. (Including nutrient recycling,) but something still nags me.

Most mulch is wood chips, a veritable endless supply source, and readily available to arborists, or even just plain old tree trimmers. But if my reasoning is right, (which is often not), most mulch comes from ground up wood, or brush, that was trimmed away for various reasons. One of these reasons is removing dead wood, or even dead trees, most notably trees that have died from various fungal infections...(ie, dutch elm, verticillium wilt, or oak wilt).

Taking this to another step, we are taking disease infected material, and placing around the root structure of healthy trees. I am not a scientist, but the equation does not really sit well with me.

There is the commercially available mulch from nurseries, and landscape yards, but I question where these wood chips come from also. Then there is the dye. I have never heard of this being phytotoxic, yet I have never been given a chemical breakdown of this material either. I do know that this dye does run on some occasions, usually in a combination of hot sun, and irrigation. And where does the parent material for these commercially available chips come from?

I would really like to see if there is a connection between the increase in wood chips recycled as mulch, and the spread of vascular fungal infections. Maybe this is not pc, because mulching seems to be an answer for almost all ailments, and recycling wood chips is a viable goal.

Just because a practice is highly recommended, (and even proven sucessful in many cases) I do not believe we should ever quit questioning ourselves, and our colleagues about even the simplest and most trusted practices.

Just a thought put out there to the rest of you. I am not against mulching by any means, but just asking a question.

It seems whatever we are doing to control diseases on a large scale is having limited, at best, sucess.

Just trying to see if anyone else has investigated this end at all, or maybe I just missed the answer somewhere.

 

[ATH]

Those are all great questions, and very legitimate concerns.

In fact a lot of nurseries continue to spread Phytophthora by re-using uncomposted grindings from previously infected plant material.

Not to over-simplify the answer...but there is a difference between mulch and wood chips. It does not go much deeper than that.

Mulch should be at least 6 months old (depending on climate conditions), and have started to compost. The heat built up in a good mulch pile will kill these diseases. Some diseases will die simply because there is no 'vector' for them to live and reproduce on.

Of course, that doesn't mean that you just pile the chips and forget about it until next year. You will build up toxic chemicals through extended periods of anaerobic respiration within the pile. That is why it is important to periodically turn the pile.

 

[Yellowdog]

Those are all great questions, and very legitimate concerns.



Mulch should be at least 6 months old (depending on climate conditions), and have started to compost. The heat built up in a good mulch pile will kill these diseases. Some diseases will die simply because there is no 'vector' for them to live and reproduce on.
QUOTE]


That's how I understand it. I make and use a lot of juniper wood chips. The shaggy bark mixes with the chips and is good to use "as is" after sitting for a few months. Best to turn it over a bit but it will get rich and break down if moisture and air are added.
for oak and other trees suspected of being diseased, I would definitely quarantine the chips for a while. I have to haul oak-wilt chips and only keep them in the sun, away from other trees, and in piles where they will generate heat. Takes green wood to get the process going so dead trees don't compost as well but the fungus can still be active within the pile for a while until it runs out of specific moisture requirements.
I would always err on the side of caution or buy bagged, composted mulch until you have your own supply aged.

 

[oldugly]

I am not really confident in recommending something I cannot guarantee will be helpful and not harmful. Personally I am not confident that my chips are segregated efficiently, and I really do not understand how any tree service could, without a lot of extra work. time, cost, etc. I don't dump my truck until it is full, and usually that is after a mixture of several trees have been chipped. Although some may take it as an insult, I don't think most arborists, or plain old trimmers, will segregate their chips properly, if they can find a free dumping sight. It is a financial matter.

After a few months in the pile, most of the fungai may be killed, or nuetralized but unless we are certain, We could easily be doing more harm than good. This brings up the commercial landscape chips, the dye I mentioned earlier, and the questionable sources of the parent material.

 

[oldugly]

I am not really confident in recommending something I cannot guarantee will be helpful and not harmful. Personally I am not confident that my chips are segregated efficiently, and I really do not understand how any tree service could, without a lot of extra work. time, cost, etc. I don't dump my truck until it is full, and usually that is after a mixture of several trees have been chipped. Although some may take it as an insult, I don't think most arborists, or plain old trimmers, will segregate their chips properly, if they can find a free dumping sight. It is a financial matter.

After a few months in the pile, most of the fungai may be killed, or nuetralized but unless we are certain, We could easily be doing more harm than good. This brings up the commercial landscape chips, the dye I mentioned earlier, and the questionable sources of the parent material.

 

[Kneejerk Bombas]

Vert. wilt is the only disease that has been shown to last a long time in wood chips. If you have a lot of Verticillium in your area, and susceptible trees, use caution.

The big Wilt diseases (Oak Wilt and DED) need a way into the trees vascular system, which a surface application of chips won't do. The fungus dies quickly once the tree is chipped.

Insects are able to move on their own. Unless the wood source is exotic, you're ok.

I don't know anything about SOD.

What else is there?