I searched the forum for "sawdust" and came up with nothing.
We planted fruit trees ever since we moved into our house, and we've added at least one tree per year. Our house was vacant for a few years and our yard was out of control when we moved in. You could say the yard was/is "wild."
Year after year it has been a challenge to contain our yard, the grass is out of control, weeds are rampant. This year I decided I was fed up with the grass, and wanted to destroy it. I bought 12 yards of Doug Fir sawdust. After a yard cleanup company killed off a lot of the overgrowth I started putting sawdust on the ground and around my fruit trees (to kill off the grass and weeds). I figured, "people use wood chips, so why not saw dust?"
I didn't stop to think if this will be a danger to my trees (I know, pretty stupid of me), and I haven't found a clear answer from Google, and I just stumbled upon this forum.
Will my trees be okay? It's been less than a week after putting the sawdust around the trees and I noticed some of the fruit forming on my plum started falling off, and many of my Oregon green fig emerging fruit has shriveled and fallen off. (Though not all fruit has come off the plum and Oregon green fig.) There are a variety of fruit trees in my yard: dwarf apple (4 types in one), dwarf cherry (4 types in one), dwarf pear (4 types in one), plum, persimmons, Oregon green fig, and a Turkish brown fig.
(I fertilize with Winchester Gardens fruit tree spikes. I've used them for the past year and a half with amazing results.)
(Again, the sawdust is Doug Fir; it isn't oak or cedar.)
I think the fir sawdust is fine, and had actually heaped it around my trees years ago, when I had access to it.
It’s not a good ‘soil amendment,’ as it will sap the nitrogen from the soil while it breaks down. But as a mulch, other than washing or blowing away, it should work well.
And welcome to the Forum 
I'm going with Viron on this one. Sawdust as a mulch should be fine. Don't dig it in, because then you'll mess up the nitrogen/carbon balance. Research has shown and my experience tells me that if you leave it on the surface, it will help retain moisture in the summer, discourage weeds, and the worms will take the organic material down when they are ready for it. In the short run, it's not a soil amendment, but over the long run it will make a huge difference in improving the drainage and microbial life in your soil, improving your likely bacterial/fungal balance, and therefore will eventually be a good soil amendment.
John S
PDX OR
PH?
I have access to lots of sawdust...alder, maple, pine ...fur. Was always worried about using as a mulch under my fruit trees because I was concerned about soil getting too acid. Is this a concern? If not, mulching with sawdust would be a wonderful idea. thank you
For the most part ‘fruit trees’ prefer a more acid soil. I suspect the sawdust you have access to would be fine, with the fir & pine adding acidity while the hardwoods basically leave it neutral. But for mulch to become 'soil' requires nitrogen, so piling on sawdust would also keep nutrients from your trees ..as it breaks down the sawdust first…
To me, sawdust would be to keep the soil moisture up - and the weeds down - and hopefully not provide voles too much cover... As a ‘soil amendment,’ it’s not only a very slow process, it’s not the best, even if it’s free. Now rotted sawdust is something else ... though requiring maybe a decade to get good ~
Idyllwild
simplepress
jafar
Marsha H
Viron
John S
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