From lrbulluc@unity.ncsu.edu Tue Nov  2 00:03:59 1999
Date: Mon, 16 Aug 1999 10:23:12 -0400
From: Russ Bulluck <lrbulluc@unity.ncsu.edu>
To: Joel Brooks Gruver <jgruv@wam.umd.edu>
Cc: sanet <sanet-mg@ces.ncsu.edu>
Subject: Re: stability in agroecosystems

Joel,

I'm not sure if this is exactly what your are loking for, but Deb Neher has
looked at medium- and long-term perenial systems and annual systems, and the
effects on microbial biomass and nematode communities.  These are definitely
non-crop!

Neher, D.A., and Campbell, C.L. 1994. Nematode communities and microbial
biomass in soils with annual and perenial crops.  Applied Soil Ecology
1:17-28.

--
Russ Bulluck
Ph.D. Candidate
Department of Plant Pathology
North Carolina State University
PO Box 7616
Raleigh, NC  27695-7616

http://www.cals.ncsu.edu/plantpath/Personnel/Students/webpage.htm

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The soil population is so complex that it manifestly cannot
be dealt with as a whole with any detail by any one person,
and at the same time it plays so important a part in the soil
economy that it must be studied.
--Sir E. John Russell
The Micro-organisms of the Soil, 1923
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



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From jgruv@wam.umd.edu Tue Nov  2 00:07:43 1999
Date: Wed, 13 Oct 1999 12:06:20 -0400 (EDT)
From: Joel Brooks Gruver <jgruv@wam.umd.edu>
To: sanet-mg@amani.ces.ncsu.edu
Subject: harnessing endophytic and epiphytic relationships

Hello to all...

While pondering the ecological implications of crops with resistance
to herbivory through plant expression of microbial endotoxins (e.g. BT), I
wondered about the potential for increased utilization of endophytic and
epiphytic microbe/plant relationships to manage phytophagous insects.

My understanding is that some turf grasses (e.g. tall fescue) have few
insect pest problems as a result of their hosting of endophytic microbes
which live within the plant and produce compounds that are toxic to plant
feeders... yet this same relationship causes serious problems for
livestock that graze upon endohyte infected forages.

I wondering about the potential for utilizing endophytes to protect grain
species from insect herbivory. Would the endophyte's endotoxins be
expressed in the grain causing problems for grain consumers ? My vague
understanding of the tall fescue endophyte lifecycle is that the endophyte
is carried by the seed.

A major focus in the Ecology of Agriculture class that I am teaching is
positive interactions between species and the potential for much greater
utilization of these interactions in agriculture. 

What would be the benefits of having an endotoxin synthesized by an
endophytic organism rather than by the plant itself ?

My understanding is the BT is not an effective epiphytic organism
otherwise live cultures could be sprayed on crop foliage that would
persist and multiply. Are there adapted epiphytic microbes that can be
used to reduce insect feeding ?

What would be the benefits of having an endotoxin synthesized by an
adapted epiphytic microbe rather than the host plant ?

What is the potential for utilizing endophytic and epiphytic/plant
relationships in agricultural systems ?

Joel Gruver
Center for Agriculture, Food and Environment
Tufts University


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From jgruv@wam.umd.edu Tue Nov  2 00:12:42 1999
Date: Thu, 5 Aug 1999 23:51:28 -0400 (EDT)
From: Joel Brooks Gruver <jgruv@wam.umd.edu>
To: sanet <sanet-mg@ces.ncsu.edu>
Subject: stability in agroecosystems

Hello to all...

I am wondering if anyone is familiar with studies that looked at the
population dynamics of non crop species in early succession
agroecosystems. Are there studies that showed that under extended
periods of uniform management/ecosystem disturbances (e.g. a long term
cropping experiment with annual crops), populations of some non-crop
species tended to stabilize while others did not ?

Certainly there are studies of changes in weed and arthropod populations
over time in long term experiments.

Can anyone refer me to an article in which non-crop species
population dynamics over time are discussed in terms of cropping system
sustainability/unsustainability ?

Joel Gruver
Soil Quality Research
U of MD


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From london@metalab.unc.edu Thu Dec  2 00:16:26 1999
Date: Mon, 16 Aug 1999 14:15:29 -0400 (EDT)
From: "Lawrence F. London, Jr." <london@metalab.unc.edu>
Reply-To: permaculture <permaculture@franklin.oit.unc.edu>
To: permaculture <permaculture@franklin.oit.unc.edu>
Subject: Stability of ecosystems (fwd)



---------- Forwarded message ----------
Date: Mon, 16 Aug 1999 10:23:12 -0400
From: Russ Bulluck <lrbulluc@unity.ncsu.edu>
Subject: Re: stability in agroecosystems


Deb Neher has looked at medium- and long-term perenial systems and annual
systems, and the effects on microbial biomass and nematode communities.

Neher, D.A., and Campbell, C.L. 1994. Nematode communities and microbial
biomass in soils with annual and perenial crops.  Applied Soil Ecology
1:17-28.

--
Russ Bulluck
Ph.D. Candidate
Department of Plant Pathology
North Carolina State University
PO Box 7616
Raleigh, NC  27695-7616

http://www.cals.ncsu.edu/plantpath/Personnel/Students/webpage.htm

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The soil population is so complex that it manifestly cannot
be dealt with as a whole with any detail by any one person,
and at the same time it plays so important a part in the soil
economy that it must be studied.
--Sir E. John Russell
The Micro-organisms of the Soil, 1923
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~




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