08-12-2005, 08:52 PM
posted to rec.gardens
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will Round Up kill dormant southern grasses
Stephen Henning wrote:
Wolf Kirchmeir wrote:
Roundup type herbicides are actually variations on the natural growth
hormones, and work by tricking the plants into overextending themselves.
AFAIK, they are taken up through roots as well as leaves. Being
hormones, they don't last long when the plants die, which is the reason
you can replant or reseed with no ill effects about two weeks after the
weeds have died.
No, you are confusing glyphosate (Roundup) with 2,4-D (weed killer) and
2,4,5-T (brush killer)
2,4-D is a growth hormone that stimulates the plant to grow so much it
kills the plant. It works best on broad leafed herbaceous material
except won't work on grasses. That is the reason it is commonly sold as
"weed killer" for lawns.
2,4,5-T is also a growth hormone but is much stronger than 2,4-D. It
kills perennial woody materials but not grasses. That is the reason it
is commonly called "brush killer". Unfortunately, dioxin is a common
impurity in cheaper grades of 2,4,5-T.
glyphosate (Roundup) only enters through green tissue (leaves and green
stems) and must be transported by the plant to the roots where it kills
the roots. It is best applied on mature green plants that are
transporting sugars to the roots. It will not affect very young plants
or plants that are dormant. It gets neutralized up by the clays in
soils and will not affect roots directly. It is broad spectrum and will
kill most any plant. It works equally well on all herbaceous materials,
grasses and woody perennials.
thanks for the info.
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