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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
>>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
>>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.
Dear Ross: What a joy to find that nematodes can control the iris borer! I
am fortunate here, in never having seen a borer in this garden. But they
suddenly appeared just 30 miles north, and I fear they could attack here at
some time in the future. Thanks again for the information. Lloyd Zurbrigg
in Durham NC

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