Also, should I use the concentrated weed killer, or use the regular diluted one? I currently use the Round-up Brsh killer, "ready to use". I do not know yet how effective it is.

"Not only is a copper nail not only not going to kill the tree, but it is a primary components of many fungicides."

Inconclusive, irrelevant and unscientific for several reasons.

The applications are entirely different. They have not presented any evidence that the copper present in fungicides, which are applied to the outside of the plants even migrates in to the plant, nor have they established the quantities of copper and how they relate to each other. Toxicology is as much about quantities and their applications as it is the material in question. Also, I fail to see why they took fungicides as their evidence. Surely the fact that copper is present in both soil and plants, and that plants purposefully asorb it and use it for biological processes is more revelevant and compelling to the issue?

However, their comparison is particuarly illogical as the copper in fungicides is part of a different compound to the copper in nails. The importance of different compounds is hard to describe without an example. Hydrogen, carbon and nitrogen are a good example. Collectively they form some 31% of the human body's mass, and they're exceptionally important materials without which we could not exist. However, they may form a number of different compounds, one of which is hydrogen cyanide, a very potent toxin that can be fatal in tiny doses. For similar reasons the copper was never the issue, but rather the form it takes.

They have failed to convince me that the copper in fungicides have any relation to the copper in nails, shown no evidence that copper in fungicides even passes through the plant's surface, and they haven't shown any comparisons between the dosage. It may be that the copper in one nail could make several thousand gallons of fungicide, I simply don't know and get the impression they haven't any idea either.

It may well turn out that I'm wrong and they're right about the main issue, if copper nails kill plants, but I would like to base my opinion on more compelling evidence than this.

Now the problem is the strong root system of the pear spreading everywhere under the ground and poping up all over with small new twigs and leaves on the earth surface. I cut the twigs with a bush cutter once a while. But they will become more, thick and stronger. Will they continue to grow, causing nearby concrete damage and messing
up my flower bed and grass? How to kill those twigs and roots, without damaging the surrounding bushes, trees and grass?

Any advice is helpful. Thanks a lot.

Yangming Cao,
Fresno Ca.