Q.
I
have a gravel driveway and do not like to have weeds come up through
it, but I hesitate to use herbicides. I have used chlorine bleach to
kill them in the past, but I am wondering if there is something else
I can use that will keep the weeds down in an environmentally
friendly way.
A. Save
the chlorine bleach for use in your laundry. It is less environmentally friendly than an application of the herbicide
Roundup® (glyphosate).
The acute toxicity of products is determined
by a test known as LD50. Basically, the product being
tested is given to a population of test animals – usually rats - in
increments measured in milligrams of product per kilogram of test
animal body weight. The amount it takes to kill fifty percent of the
test population is the LD50. The lower the LD50
of a product, the more toxic it is, because it took less of it to
kill fifty percent of the test population. The oral LD50
of glyphosate is 4320 mg/kg while the oral LD50 of
chlorine bleach is 192 mg/kg.
Spotted spurge grows fast along walks
and driveways during hot, dry weather
There are
formulations of vinegar – these are much stronger than what you use
in the kitchen – that are labeled as herbicides, as well as
soap-based herbicides such as Weed Aside™, that are much safer than
bleach.
You could also pour boiling water on them periodically
through the growing season. You will have to make repeat
applications as needed because none of these methods – including
Roundup® – will provide season-long weed control.
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