It was great to see those results. I would suggest one thing though that is
that everybody uses the application rate and areas used in the study.
Changing things like that may mean you dont get the control you are looking
for and therefore your money may be wasted. Do make sure your supplier is
selling you Steinernema carpocapsae, as from the advertising I've seen from
some sellers they make a lot of unsubstantiated claims for lots of different
nematodes. I would put that 4-5 per square foot application rate in that
catagory. I dont know what that was recommmended to kill but it seems very
low. Some sellers seem to be recommending rates like that so their product
doesn't seem so expensive. Anything that doesn't work is very expensive.
I hope everybody overthere with borer problems tries some S.
carpocapsae, I am very interested in hearing what you all think of them,
whether they worked (who you bought them from) and how they compared to
using chemicals (ease of use etc).
bye and Merry Christmas from down under
The views expressed above are my own and not those of my employer.
At 09:03 AM 23/12/97 -0700, you wrote:
> I have had an opportunity to digest the U. Of Maryland research and
>talk to some folks in the field and have some preliminary conclusions.
>=46irst, if you want to know more about nematodes per. se., please visit thi=
>site (http://ianrwww.unl.edu/ianr/plntpath/nematode/wormepns.htm) It will
>give you good general background about nematodes. (There may be another
>good site, can't remember at the moment.)
> Last April, researchers at the University of Maryland applied two
>kinds of nematodes and two commonly used chemical treatments to compare
>results on iris borer. Nematodes used were: Steinernema carpocapsae (known
>as Sc) and Heterorhabditis bacteriophora (known as Hb) . Chemicals tested
>were: dimetheoate (Cygon) and imidachloprid (Marathon). These were used on
>groups of iris which had be=00=00=00=00=00=00=05en intentionally infected=
> with borer the
>previous fall. As I said, the plants were treated in April, and dug up in
>mid July. The findings were that one nematode Hb (Heterorhabditis
>bacteriophora), dimetheoate (Cygon) and imidachloprid (Marathon) all
>eliminated 87% of the borer problem, and Sc (Steinernema carpocapsae) the
>other nematode, did better, eliminating the borer population completely.
> I know many of you have been using Cygon, and given these results,
>I want to urge you to consider changing. Cygon is a nasty chemical, rating
>very high on the government's LD toxicity list. It's high toxicity is the
>reason it works, but on the other hand, using chemicals like this is like
>conducting nuclear war on your garden. It kills everything. Unfortunately,
>most of what it kills are beneficial organisms. It is also a little risky
>to use. I have often wondered if Cygon wasn't a major contributor to the
>reason virgin soil seems to do so much better for iris. Marathon is fairly
>new (at least to me), and I don't know how dangerous it is. It is a
> By contrast with both, nematodes are so safe that the government
>does not even bother to regulate their use. Nematode suppliers will also
>tell you that nematodes (depending on the variety) will control up to 300
>other garden pests, while disturbing few beneficial garden organisms.
>(Nematodes are relatives of earthworms.) I find that a fascinating prospect.
>The one (sort of) advantage we have with iris borer over other pests is
>that we know where to find them. Unfortunately where we find them is in our
>iris plants! In the research study, nematodes were applied to a one square
>foot area around each infected plant at a rate of 500 nematodes per square
>inch (remember that nematodes are microscopic). (The researchers also
>tested a 1,000 per square inch rate and found that the 500 rate was just as
>effective.) Nematodes are routinely purchased per million, which would mean
>that at the 500 per square inch rate, a million nematodes would treat 2,000
>square inches. The researchers treated a square foot around each plant (144
>square inches), but I think one might be able to do less, perhaps an 8 inch
>square around each plant. The reason I suggest this is that normal nematode
>rates for broadcast application run more like 4-5 per square foot, so 500
>is considerably higher than normal.
> Anyway, using a 12" square, a million nematodes could treat 14
>plants. Using an 8" square you could treat closer to 30 iris plants. All
>these numbers are approximations because when you receive the nematodes thy
>usually come in a damp sponge and you then disperse them in a bucket of
>water. The mix is then poured or sprayed over the area you want to treat.
> Although possible, foliar treatment with nematodes does not seem to
>be a good option=00=00=00=00=00=00=05=83pinion is not based upon research,=
> however. The
>general consensus is that chances of success are greater using nematodes
>applied to the soil. A factor to remember is that nematodes don't like cold
>soil. So when you treat, for optimal results, make certain that your soil
>temperature is at least 50 degrees to a depth of 5". Nematodes will last at
>least two months in the soil if there is nothing for them to feed on and
>reproduce. I know of one fellow in Vermont who has had nematodes remain in
>his garden for six years.
> One of the suppliers used in the study, HydroGardens of Boulder
>Colorado (800-634-6362) sells nematodes at $8 per million, 6 million for
>$30. Because nematodes are living organisms they must be shipped by two day
>air, and this adds about another $7.50 to the cost. Several people or a
>club could get together however, and reduce the cost. Biosys of Columbia,
>MD, the other nematode supplier used in the study, apparently had
>formulated a water dispersable granule for the nematodes which may have
>made normal shipping possible. However, they are apparently out of
>business. There are many other nematode suppliers around, so shop around. I
>can recommend M&R in Durango Colorado (800-526-4075) from personal
>experience, I have not checked their prices recently. The fellow who
>supplies nematodes to Garden's Alive has an excellent reputation, but at
>the moment they are offering a different nematode species than SC.