Wood chip mulch

I have been lucky enough to get a ton of free and delivered wood chip mulch from utility line crews working in my area. I'm planning on using it to mulch large areas around trees in my large yard to cut down on mowing. Some are established Austrian pines. Some are young established pines of mixed variety. Some are deciduous trees that I can't identify.

The wood chips are of mixed wood and some piles have a great deal of leaf debris. I realize the leaves will decompose so I'm not too worried about that. But I know there is at least some black walnut in some of the piles.

How worried should I be about mulching around trees with these wood chips?

Thank you
Jennifer

This is a quote from Oklahoma State Extension:

"The concern is that naturally occurring allelopathic chemicals will be transferred directly to susceptible plants. In research that Dr. MacDaniels conducted in the 1950s, he found that he could not induce wilting in susceptible solanaceous plants when planting them directly into fresh black walnut wood chips. Many do not consider this a problem, but there has been no follow up on this research. Bark and fruit contain the concentration of juglone, but very little is in the wood itself; this may account for Dr. MacDaniels' findings."

and this is a quote from the Vermont Extension:

"Black walnut trees should not be chipped for landscape wood chip use. Black walnut trunks, branches, and roots contain naturally occurring chemical compounds that inhibit plant growth."

Great huh? I don't think anyone really knows for sure. I would probaby use them. The Oklahoma Extension information is at least backed up by some research.

This message was edited Sep 10, 2008 2:14 PM

I have a question, Snapple. Would you wait a year before applying the mulch? I've heard that you should and am not sure.

Thanks for the info Snapple! I was hoping I could get away with it since its not all black walnut.

Jennifer

It depends on how much you are putting down and where they are going. If it's a modest layer over the root zone of established trees and shrubs then use them. Add a small amount of nitrogen fertilizer to counteract the nitrogen depletion. In my experience there is no better mulch in that situation.

I would not, however, use fresh chips on shallow rooted annual flowers, herbaceous perennials or in vegetable gardens except for pathways. Wood chips do deplete nitrogen in the very top soil layer. It's safer to let them age for year.

Okay, thanks. That helps, as we just got some, too.

Do NOT use this type of mulch in any areas adjacent (connected) to your home or other buildings. Since it is largely chipped wood PULP, it is prime termite food. This will not be a problem around trees or beds away from the house, but it could be a serious problem otherwise. A few years ago, I got a call from some friends who said they found termites in their mulch. In over 20 years of landscaping, I had never seen one termite in hardwood bark mulch, and I use it extensively at my own home, and I live in a wooded area. So, I was interested and went over. What they had done was spread "utility line" mulch (which they had obtained for free) all around their house. When we raked back an area of mulch, it was positively swarming with termites. It was a sight! To make a long story short, the termites had used the mulch to spread into the house, and the owners had to do thousands of dollars in repairs to the wood framing, and especially the floor joists. So, be careful to keep it separate from the house landscaping.

I'm glad you brought that to attention HoosierGreen. Same with firewood. Never stack it near the house and keep it up off the ground if you can.

Very good point. Thanks.