I am planning to renew my weedy, troubled lawn by killing the grass
with Round Up Weed and grass Killer, and reseeding. I know that I have
to protect any flowers that are near where I plan to spray. But there
is a tree -- and old 100-foot robust tree with extensive roots --
right in the middle of the lawn. Question: will the weed killer affect
the tree and its root system? If so what can i do to still knock out
the grass, and not harm the tree?

On 19 Sep 2003 07:42:36 -0700, (F Paul) wrote:

I am planning to renew my weedy, troubled lawn by killing the grass
with Round Up Weed and grass Killer, and reseeding. I know that I have
to protect any flowers that are near where I plan to spray. But there
is a tree -- and old 100-foot robust tree with extensive roots --
right in the middle of the lawn. Question: will the weed killer affect
the tree and its root system? If so what can i do to still knock out
the grass, and not harm the tree?
It's hard to answer this question without seeing the site. Assuming
you believe the company line about Roundup (please don't get us
started), it is harmless in this case when applied to grass without
getting any on tree leaves.

BUT, many trees send up small sprouts (suckers, water sprouts, it gets
a few names) from their roots. If you have any of these small trees
poking up in your grass (and perhaps even if you don't--they may be
getting mowed down with the grass) you may get the chemical into your
tree's roots without realizing it. Even then, the tree should
withstand it. Roundup is too weak to affect most woody plants.
Still, the more you do to your tree, the greater the chance it will
decline and/or die. Be aware of current stressors the tree is coping
with (like drought, abnormal swampiness, overfertilization, root loss
from trenching or soil compaction, etc.).

Keith
For more info about the International Society of Arboriculture, please visit http://www.isa-arbor.com/home.asp.
For consumer info about tree care, visit http://www.treesaregood.com/