Re: RE: Roundup and other herbicides
- Subject: Re: [sibrob] RE: Roundup and other herbicides
- From: J* M* <m*@cstone.net>
- Date: Tue, 20 Jul 2004 18:16:55 -0400
Hi All,
I can add a few other things to this thread about herbicides.
There are many different formulations of Roundup. They are in different
strengths, for the most part, and some have spreader stickers and some
don't. There is also the new Roundup "Fast Kill Foam", knocking plants
to the ground in 24 hours.
I have used Roundup Pro professionally for many years. It is quite
inexpensive and quite non selective. I mix it at the rate of 2.75 oz per
gallon. At that rate it does kill or set back almost all weeds, and SI
and JI's, as well as two types of nutsedge, but not the tough one,
purple. I strongly suggest not using this formulation at this strength
on your SI's and JI's, as well as Japanese roof, and most bearded of
modern form. It does not kill Psuedacorus, but does ruin the foliage.
Another great pre emergent for Iris, ( one that actually lists Iris on
the label) is Surflan, quite effective on some tough annuals. It is
closely related to Treflan. As to Snapshot, I don't have a label at
hand, but I doubt that it is listed for Iris's as half of it's active
ingredient, Gallery, does not list it as safe to apply. This doesn't
mean that it doesn't work, it means that the label doesn't list it, and
it is a violation of federal law to apply it to plants not listed. This
mostly affects those with Pesticide Applicator licenses.
Back to Roundup. Very low rates of Roundup will frequently kill weeds
in ornamental plants, and the plants will survive, but be damaged for
the short term. Iris and Daylilies come to mind. At the very low rates,
the weeds take weeks to die, typically. Jim
Bob Hollingworth wrote:
>Like a lot of other people we use Roundup (2.5 oz/gallon) all year round in
>the Siberian beds (though always trying to avoid direct contact of the
>spray with the irises). Every year a handful of flowers show the pale
>colors and changed form typical of Roundup injury, but I've never seen the
>vegetative parts of a plant much affected or had one die, so there is some
>degree of resistance which is a blessing. Here are a few more observations
>on herbicides and Siberians:
>
>Snapshot (2.5% granular) is a pre-emergent herbicide mixture - a sort of
>improved version of Treflan. We use it very widely around the new seedlings
>and it has never caused any problem. As long as it is rained or hoed in
>soon after application, it does a great job. Poast (common name;
>sethoxydim) is a grass-selective compound. I never saw any problems with
>Siberians oversprayed with this. However, a few years back I switched to a
>closely-related compound Select (clethodim) because it is supposed to
>control annual bluegrass which Poast doesn't. This was a mini-disaster.
>Sprayed on the plants while they had bloom stalks, it blasted every bud -
>they just dried and withered. Fortunately it was used on a very limited
>area. The plants themselves weren't killed, but it was a nasty surprise and
>the last time I used Select. Not entirely grass-specific, whatever the
>claims! The last grass-specific herbicide that we use now as a primary
>compound is Fusillade II (fluazifop-P-butyl). This seems to be pretty much
>harmless to irises, though I haven't sprayed them when in bloom. Lastly, a
>really useful compound is Lontrel (Stinger; common name: clopyralid)) which
>is a plant hormone analog like 2,4-D. It works wonders on thistles and
>compositae like dandelions and ragweed and a few other significant weeds.
>It doesn't seem to harm the irises but it does cause twisting of the flower
>stems so it shouldn't be used when they are in bloom. With care, you can
>get just about every weed with these compounds. But, these mixed
>experiences do clearly show that the flowers are often the most sensitive
>part of the plant and that, as Harold says, some initial tests on a limited
>area before believing anything you read or are told can save some grief. It
>would be interesting to find out how other people with large plantings
>handle weeds. Weed pressure is relentless and makes most of the work in
>growing Siberians for us. Bob Hollingworth
>
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