Re: Nematodes

Ross, thanks for taking time to find the nematode info.  Almost makes me
wish we had borers here to experiment on.......Nah.

Merry Christmas!

Barb, out in snow-laden Eldorado.


-----Original Message-----
From: Ross <ross@dsrt.com>
To: Multiple recipients of list <iris-l@rt66.com>
Date: Tuesday, December 23, 1997 9:03 AM
Subject: Nematodes


> 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=
>s
>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
>systemic poison.
> 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.
>Ross
>
>
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