On 4/5/10 1:23 AM, Stewart Robert Hinsley wrote:
In message
,
Billy writes
In article ,
"David E. Ross" wrote:
On 4/4/10 7:47 PM, MiamiCuse wrote:
South Florida zone 10b.
I have planted some Costus (Ginger family) in a 50' long planter area.
However the weeds are growing like wild fire and I am unable to keep up
with
pulling them. I wanted to use some weed killer to control the weeds
(clover
leaf type, see a pic here
http://www.biology-blog.com/images/b...-leaf-3100.jpg ),
but
have heard that weed killer will also kill plants that have rhizones which
my Costus is.
Is this true? Is there a better way to control the weeds beside hand
pulling?
Thanks,
MC
Take a piece of the weed -- not merely one leaf -- to a "real" nursery
(not a lumber yard or hardware store) for identification. This might be
oxalis instead of clover.
The photo looks like oxalis.
There is a specific weed control that severely burns oxalis,
sufficiently to kill most of it, without harming other plants (except
for spotted spurge, another weed). Sold under various brand names, it
contains ammonium thiocyanate, which quickly decomposes into a urea form
of fertilizer; sodium thiocyanate is about as effective. Any oxalis
plants that survive must be hand dug, for which I recommend the use of a
paring knife. Be alert! Oxalis readily forms seeds, which are not
affected by the chemical; the thiocyanates act only on growing foliage.
If your weed is indeed clover, hand pulling is the best control. Do
this before it flowers, and you won't have to repeat. Try to leave some
of the roots in the soil; they are an excellent source of nitrates for
nurishing other plants.
Sorry David, but it looks like bullshit to me, thiocyanate is sulfur +
cyanide. Pull the god damn weeds. Don't be a lazy ****. You don't want
to eat heavy metals. Oxalis isn't that invasive, and kids love to chew
it, even if it does bind up calcium.
I don't find Ammonium thiocyanate as a narrow-spectrum weedkiller
particularly plausible, but there are no heavy metals involved.
Google's not being particularly informative today, but it looks as if
ammonium thiocyanate is usually used combined with aminotriazole
(amitrole) - and acts by slowing the action of the aminotriazole
allowing it to reach the roots and kill the whole plant, rather than
just the leaves.
This combination is marketed as an oxalis killer
(http://www.agspray.net.au/msds/oxalis.pdf), but it is also recommended
for the control of "grasses, broad-leaved weeds ... & nut-grasses".
Given that range I expect that it will kill Costus quite happily.
Aminotriazole, fide Wikipedia, is a carcinogen.
There are products marketed for the control of broad-leaved weeds in
pastures and cereal groups. But while Costus is a monocot, sensitivity
to weed killers doesn't line up nicely with phylogenetic clades (e.g.,
fide Wikipedia, bromoxynil is used with flax and mint, as well as with
monocot crops), so it cannot be assumed that Costus is not sensitive.
Broad-leaved weed killers tend to be nastier chemicals.
The last time I looked at a bottle of Oxalis-X, the only active
ingredient was ammonium thiocyanate. No amitrole, no other herbicide.
Ammonium thiocyanate will burn other plants; but in most cases it will
not burn sufficiently to kill the plant. However, the label did warn
against spraying it on or near junipers. It is effective against
growing oxalis and spotted spurge and leaves no residue other than urea
(a fertilizer) and sulfur (good in my alkaline soil).
I haven't bought Oxalis-X in a long time. Fortunately, oxalis is now a
rare weed in my garden. When I find it, my paring knife digs it out
(with help from my right hand).
Unfortunately, spotted spurge is too common in my garden. But it tends
to grow my decomposed granite walkways where I can use Roundup.
One precaution in keeping oxalis out of your garden is to inspect
carefully all containers of new plants at the nursery. Oxalis is often
found growing in the containers that also contain the shrub or perennial
you really want to buy. Buy only the desired plant, and reject any that
come with oxalis.
--
David E. Ross
Climate: California Mediterranean
Sunset Zone: 21 -- interior Santa Monica Mountains with some ocean
influence (USDA 10a, very close to Sunset Zone 19)
Gardening diary at http://www.rossde.com/garden/diary