Subject: ? Root Nematodes

From: [email-masked] (CMLawrence)
Date: 20 Mar 1995 19:55:42 -0500

Does anyone have any Organic soultions for Root Nematodes?  I have tried
planting a cover crop of French Marigolds and then tilling them under per
the instructions of an aticle I found.  This was to no avail.  The little
devils were back with a vengence.  Thank you in advance for all advice.

Charlotte

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From: [email-masked] (Christine Owens)
Date: 22 Mar 1995 03:26:34 GMT

>devils were back with a vengence.  Thank you in advance for all advice.

Try an application of beneficial nematodes.  They will go to
war with the root ones.

Chris Owens

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From: [email-masked] (Graham Thurston)
Date: Wed, 22 Mar 1995 17:02:19 GMT

>Chris Owens

No they will not!!! 

The root nematodes are plant-parasitic, the beneficial 
nematodes are entomopathogenic and have no effect on root nematode 
populations.  The beneficial nemas are searching out insect hosts and can not 
infect other nematodes, plants, or vertebrates.  About 10 years ago in the 
nematology literature there was one rather poorly done study that suggested a 
transitory reduction in numbers of some soil nematodes after the addition of 
massive numbers of entomopathogenic ones.  However, the data were never 
analyzed and the reported phenomenon has never been found since.

Graham Thurston
(entomopathogenic nematode specialist)

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From: [email-masked] (Christine Owens)
Date: 22 Mar 1995 03:26:34 GMT

Chris Owens

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From: [email-masked] (Graham Thurston)
Date: Wed, 22 Mar 1995 17:02:19 GMT

No they will not!!! 

Graham Thurston

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From: [email-masked]
Date: Thu, 23 Mar 95 13:15:46 EST

What are beneficial nematodes?  And why are they beneficial?
Should I call Garden's Alive right now, order a bunchand add
them to my garden?
 
How will they help? And what are the signs that I need some?
 
Dave Vanderhoof

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From: [email-masked] (Graham Thurston)
Date: Thu, 23 Mar 1995 21:13:19 GMT

In article <[email-masked]> [email-masked] writes:
>From: [email-masked]
>Subject: Nematodes, Will They Help My Garden?
>Date: Thu, 23 Mar 95 13:15:46 EST

>How will they help? And what are the signs that I need some?

Dave,

Beneficial nematodes are nematodes that are pathogenic to insects and do not 
infect plants, mammals, earthworms ... . The natural environment for these 
nemas is soil, thus they will not be very effective against foliage-feeding 
pests.  They are quite effective against a wide range of insects, provided 
they are not exposed to environmental conditions that are deleterious.  This 
includes desiccation, uv radiation, hot temperatures.  Also, certain nematodes 
are ineffective against certain insect species.  For example, white grubs are 
not killed very well by the nematode species _Steinernema carpocapsae_, 
whereas the species _S. glaseri_ and _Heterorhabditis bacteriophora_ can be 
quite effective.

It will do you no good to go out and purchase the nematodes unless you have a 
specific insect problem you need to control.  After being applied to the soil, 
the numbers of these nematodes diminishes quite rapidly -- you may have 
high numbers in the soil for only a week or two after application.  

To ensure the best survival and control, the nematodes should be applied to 
moist soil late in the day and watered in with plenty of water immediately 
afterward.  Also, remember that you are dealing with living organisms and 
treat the material as such (i.e. long storage times, even in the 
refrigerator, will kill them, and pay attention to environmental conditions 
when applying).

Feel free to contact me by email for more specific information

Graham Thurston
entomopathogenic nematode specialist

[email-masked]

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From: [email-masked] (Christine Owens)
Date: 25 Mar 1995 15:54:49 GMT

>How will they help? And what are the signs that I need some?

Beneficial nematodes help in a lot of ways:  By assisting in
breakdown of organics in the soil.  By attacking microscopic
pests, and the eggs / larvae of not-so-microscopic pests.  Your
soil is probably already full of them; but if you have a major
grub infestation, adding some more can help.

Chris Owens

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From: [email-masked] (Pat and George Kiewicz)
Date: Thu, 23 Mar 1995 15:36:19 GMT

CMLawrence ([email-masked]) wrote:
:   Does anyone have any Organic soultions for Root Nematodes?  I have tried
: planting a cover crop of French Marigolds and then tilling them under per
: the instructions of an aticle I found.  This was to no avail.  The little
: devils were back with a vengence.  Thank you in advance for all advice.

When I started my garden, I had a terrible problem with root-knot nematodes.
The last two years, almost no sign of them.  All that I've done is regularly
add compost and other organic soil amendments (alfalfa, bone, and seaweed
meals especially recommended).  In addition, I apply beneficial nematodes
each year for insect control, and I've read one source which claims this
decreases the population of harmful nematodes.  

More advice: 

Destroy all infested plants rather than compost.

Nematodes cannot move far through the soil on their own, but are easily
spread by soil clinging to tools, gloves, shoes, etc. and can be moved
from infested areas in this way.  Clean allt ools before using them in
an area that has been treated, to avoid reintroducing the nematodes.

It is recommended to plant marigolds as a cover crop for two years, tilling
in all residue.  I've read at least one article that suggests that annual
vinca (Catharanthus) is even more effective than marigolds.

Chitin from sea-food wastes supresses nematodes and enhance the growth of
the fungi which prey on them.  Clandosan is a commercial product containing
chitin (though it is not certifiable by some standards as it is processed
with urea).

Heat can destroy nematodes.  Hot water soil drenches, or a season of soil
solarization might help.

I've read of adding white sugar to the soil to kill nematodes.

Good luck!

Pat in Plymouth MI
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From: [email-masked] (Graham Thurston)
Date: Mon, 27 Mar 1995 18:17:15 GMT

In article <[email-masked]> [email-masked] (Christine Owens) writes:
>From: [email-masked] (Christine Owens)
>Subject: Re: Nematodes, Will They Help My Garden?
>Date: 25 Mar 1995 15:54:49 GMT

>Chris Owens

While Chris' posts contain tremendous amounts of good information, she is 
misinformed where it comes to beneficial nematodes.  

1)  The only organics in the soil that entomopathogenic nematodes break down 
are insects they have killed  -- they don't even have a functioning digestive 
tract until they are inside an insect host.  They don't contribute to OM 
degredation otherwise.  

2)  They do not attack microscopic pests, only insects.  There has been no 
case where entomopathogenic nematodes have successfully attacked eggs of any 
insect species.  Larvae and adults of many insect species are attacked but 
even these have a variety of defense mechanisms that may, in a few cases, 
render the nematodes ineffective as a biological control agent.

Chris is right in that your soil probably has quite a few, unless you have 
been pumping various chemical pesticides into it.  However, the natural level 
of entomopathogenic nematodes in the soil is generally quite low and the 
addition of more is often adviseable.  If it is a grub infestation that you 
have, don't use _Steinernema carpocapsae_, try _Heterorhabditis bacteriophora_ 
or _Steinernema glaseri_ instead, these do a better job.

Graham Thurston