Tools, Sharpening and Power Machinery - cutting tree roots

I have to cut through some bamboo stalks that are up to 3" in diameter. Also I have to cut into their surface roots above ground, so I have to saw "down" towards the earth. Tight spaces are involved. Would a reciprocating saw be good? I've tried hand sawing but it is just too labor intensive and takes forever. This is a very hard wood. I am a petite woman so any recommedations on brands that are lighter or smaller would be appreciated. Thanks

Welcome to the forums! A reciprocating saw will work just fine. You will need a fairly aggressive blade, so do your shopping. In addition, are you trying to rid the area of bamboo? If so, cutting their roots just tickles their growth hormones. You will have to completely dig them up, or drive a metal boundary plate at least 8" into the ground to contain them. They are aggressive.

I have heard backhoes tried to takle them and failed

Bamboo is one of the hardest plants to kill

at best you may just contain them

It is a clumping bamboo, although tall, and is still in a fairly small area. Yes, I just might have to take the whole thing out.
As far as recip. saws go, would a Ryobi 6.5 amp be sufficient for something like this, and for other light chores? Isn't 6.5 amps low? I't seems to be a smaller one in size, which would be good for me. I'd like not to spend more than $100. Any other brands?

I think the Ryobi would work just fine for your budget. Get metal cutting blades w/ the least # of teeth per inch. They will stand up to the rocks and dirt better than wood cutting blades. They won't cut as fast,work the blade in and out in a sawing motion while running the saw. This will help teeth clean sawdust from themselves.
Hope this helps,
Mike

Get long blades.. Contractor quality..
Another way to get them out is dynamite, but that may not be a suitable alternative..