On 11/4/2014 2:29 PM, Jeff Layman wrote:
On 04/11/2014 15:48, Brooklyn1 wrote:
F Murtz wrote:

If I have some raised gardens with vegies in them and grass weeds start
growing can I carefully paint the weed with glyphosate without affecting
the vegies?

No matter how carefully you apply glyphosate as the 'weed' dies the
chemical will dissolve into the soil and affect your vegetable plants,
and you when you eat them, if you get any.

I am sure that with such specific claims you will be happy to provide
numerous links which support your statements.

For my own edification I clipped this:
Environmental Fate:
Soil

The median half-life of glyphosate in soil has been widely studied;
values between 2 and 197 days have been reported in the literature.7,48
A typical field half-life of 47 days has been suggested.4 Soil and
climate conditions affect glyphosate's persistence in soil.1 See the
text box on Half-life.

The "half-life" is the time required for half of the compound to
break down in the environment.

1 half-life = 50% remaining
2 half-lives = 25% remaining
3 half-lives = 12% remaining
4 half-lives = 6% remaining
5 half-lives = 3% remaining

Half-lives can vary widely based on environmental factors. The
amount of chemical remaining after a half-life will always depend on the
amount of the chemical originally applied. It should be noted that some
chemicals may degrade into compounds of toxicological significance.
Glyphosate is relatively stable to chemical and photo
decomposition.6 The primary pathway of glyphosate degradation is soil
microbial action, which yields AMPA and glyoxylic acid. Both products
are further degraded to carbon dioxide.3
Glyphosate adsorbs tightly to soil. Glyphosate and its residues are
expected to be immobile in soil.6

Water

The median half-life of glyphosate in water varies from a few days
to 91 days.1
Glyphosate did not undergo hydrolysis in buffered solution with a
pH of 3, 6, or 9 at 35 °C. Photodegradation of glyphosate in water was
insignificant under natural light in a pH 5, 7, and 9 buffered
solution.58,59
Glyphosate in the form of the product Roundup® was applied to
aquatic plants in fresh and brackish water. Glyphosate concentrations in
both ponds declined rapidly, although the binding of glyphosate to
bottom sediments depended heavily on the metals in the sediments. If
chelating cations are present, the sediment half-life of glyphosate may
be greatly increased.60
Glyphosate has a low potential to contaminate groundwater due to
its strong adsorptive properties. However, there is potential for
surface water contamination from aquatic uses of glyphosate and soil
erosion.6
Volatilization of glyphosate is not expected to be significant due
to its low vapor pressure.6

Air

Glyphosate and all its salts are very low in volatility with vapor
pressures ranging from 1.84 x 10-7 mmHg to 6.75 x 10-8 mmHg at 25 °C.1,4,8
Glyphosate is stable in air.1

Plants

Glyphosate is absorbed by plant foliage and transported throughout
the plant through the phloem.3 Glyphosate absorption across the cuticle
is moderate, and transport across the cell membrane is slower than for
most herbicides.4 Because glyphosate binds to the soil, plant uptake of
glyphosate from soil is negligible.3
Glyphosate accumulates in meristems, immature leaves, and
underground tissues.4
Very little glyphosate is metabolized in plants, with AMPA as the
only significant degradation product.3
Lettuce, carrots, and barley contained glyphosate residues up to
one year after the soil was treated with 3.71 pounds of glyphosate per
acre.61,62
Glyphosate had a median half-life of 8 to 9 days in leaf litter of
red alder and salmonberry sprayed with Roundup®.48

Indoor

All surface wipe and dust samples collected from five farm
households in Iowa contained detectable levels of glyphosate ranging
from 0.0081-2.7 ng/cm2. In six non-farm households, 28 out of 33 samples
collected contained detectable levels of glyphosate ranging from
0.0012-13 ng/cm2.63