Group Title: Agricultural research (Washington, D.C.)
Title: Agricultural research
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Title: Agricultural research
Uniform Title: Agricultural research (Washington, D.C.)
Physical Description: v. : ill. ; 25-28 cm.
Language: English
Creator: United States -- Science and Education Administration
United States -- Agricultural Research Administration
United States -- Agricultural Research Service
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Publication Date: February 1999
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Subject: Agriculture -- Periodicals   ( lcsh )
Agriculture -- Research -- Periodicals   ( lcsh )
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Dates or Sequential Designation: Began with vol. 1, no. 1 (Jan. 1953).
Issuing Body: Vols. for Jan./Feb.-Nov. 1953 issued by: Agricultural Research Administration; Dec. 1953-<Sept. 1976> by: Agricultural Research Service; <June 1979>-June 1981 by: the Science and Education Administration; July 1981- by: the Agricultural Research Service.
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Full Text









































































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FORUM


Long-Term
Experiments:
Keystones for
Future Planning

There is a growing perception that
present trends in global agricultural
production are neither sustainable nor
environmentally sound.
But that view isn't necessarily based
on scientific data. Only experiments
that have been meticulously carried
out for several decades can answer
questions about the sustainability of
agricultural practices.
That's because changes in key in-
dicators, such as soil organic matter,
can take more than 20 years to become
detectable by current analytical meth-
ods. And short-term experiments may
miss the impacts of management
changes because the measurements are
taken while the system is still in tran-
sition.
As early as 1843, scientists in Roth-
amsted, England, established long-
term agricultural experiments to learn
how crop management techniques in-
fluenced yield and soil quality over
time.
Later, researchers in the United
States and other countries set up sim-
ilar long-term projects. Some of those
experiments are still running today-
like the ones described in this issue
that were established in 1931 at
Pendleton, Oregon.
Long-term experiments can identi-
fy management practices capable of
maintaining crop yield and soil qual-
ity. They show, forinstance, that plow-
ing under the plant material left behind
after harvest-the crop residue-in-
creases soil organic matter and reduc-
es erosion.


But even as we transfer technol-
ogy that supports sustainable agricul-
ture, we have to be culturally sensitive.
Growers in a developing country may
readily adopt new tillage machinery.
But because they need the leftover
straw for feed and fuel, they may not
be able to commit to techniques such
as residue management. That makes
it even more important to understand
the impacts of various agricultural
techniques and to develop better man-
agement practices.
Long-term experiments can also re-
veal unfavorable effects of agricul-
tural practices, such as the repeated
addition of ammonium- or urea-based
nitrogen fertilizer without the concur-
rent addition of lime. That can make
the soil more acidic. Highly acid soil
is detrimental to crop growth and bi-
ological activity in soil.
Experiments like those at Pendle-
ton have a much wider application
than agriculture. They probably make
up the largest temporal and spatial da-
tabase currently available for deter-
mining impacts on any ecosystem. As
such, they afford the possibility of har-
nessing observations of past change
to predict future trends.
Internationally, the NATO-spon-
sored Soil Organic Matter Network,
SOMNET, seeks to predict the effects
of climate, atmospheric composition,
and land use change on soil organic
matter. Researchers are using data
from several long-term experiments
to judge the accuracy of computer
models in simulating such effects.
Projects are evaluating the soil's
ability to serve as a sink for carbon to
mitigate global climate changes. Soil
contains twice the amount of carbon
as does the atmosphere, and it appears
capable of storing much of the increase
in atmospheric carbon dioxide if key


agricultural practices are adopted.
The best long-term experiments
also have an archive of soil samples
that contain benefits never imagined
by the experiments' founders.
For example, soil samples have
been collected and archived at Roth-
amsted since 1843. Now, scientists can
analyze these samples to determine
how the levels of potentially toxic ele-
ments, such as cadmium and certain
dioxins, have been changing in the
soil.
A key objective for the future will
be to identify and support long-term
experiments that have been managed
properly. Most of those existing today
have survived war, drought, and pol-
itics. Commitment is needed to ensure
the continuance of those with rele-
vance and merit, as they offer invalu-
able insight into the research best able
to guide us in the 21st century.

Paul E. Rasmussen
ARS Columbia Plateau Conservation
Research Center, Pendleton, Oregon














[Parts of this Forum were
adapted from an article by the
author titled "Long-Term
Agroecosystem Experiments: Using
the Past To Guide the Future,"
which appeared in the October 30,
1998, issue of Science.-Ed.]

Agricultural Research/February 1999








February 1999
Vol. 47, No.2
ISSN 0002-161X



Agricultural Research is published monthly by
the Agricultural Research Service, U.S. Depart-
ment of Agriculture (USDA). The Secretary of
Agriculture has determined that this periodical is
necessary in the transaction of public business
required by law.
Dan Glickman, Secretary
U.S. Department of Agriculture
I. Miley Gonzalez, Under Secretary
Research, Education, and Economics
Floyd P. Horn, Administrator
Agricultural Research Service
Sandy Miller Hays, Director
Information Staff
Editor: Lloyd McLaughlin (301) 504-1651
Assoc. Editor: Linda McElreath (301) 504-1658
Art Director: William Johnson (301) 504-1659
Photo Editor: Anita Daniels (301) 504-1609
Staff Photographer: Scott Bauer (301) 504-1607
Information in this magazine is public property
and may be reprinted without permission. Non-
copyrighted photos are available to mass media in
color transparencies. Order by photo number and
date of magazine issue.
Agricultural Research magazine articles and pho-
tographs are posted on the World Wide Web month-
ly at http://www.ars.usda.gov/is/AR/.
Subscription requests should be placed with New
Orders, Superintendent of Documents, P.O. Box
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Complimentary 1-year subscriptions are available
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to: Editor, Agricultural Research, 5601 Sunny-
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This magazine may report research involving pes-
ticides. It does not contain recommendations for
their use, nor does it imply that uses discussed
herein have been registered. All uses of pesticides
must be registered by appropriate state and/or
federal agencies before they can be recommended.
Reference to any commercial product or service
is made with the understanding that no discrimi-
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Persons with disabilities who require alternative
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opportunity provider and employer.


Agricultural Research



Farmland Studies for the Long Haul 4

There's Treasure in the Soybean Genome Map 8

For More Soybeans, Dig Deep 10

New Ways To Monitor Toxins 11

Battling Food-Poisoning Bacteria 12

Can Foods Forestall Aging? 14

Melons Are on a Roll 18

Coping With Rett Syndrome 20

Sunflowers Add Variety to the Great Plains 21

Topsoil Is Alive: Keep It Fresh 21

Weevil Gets Upper Hand With Unruly Weed 22

Science Update 23









Cover: As part of long-term Agricultural Research Service experiments to learn
the effects of different land-use systems on crops and soils, chemist Chris Roager
extracts nitrogen from soil samples taken from test plots at Pendleton, Oregon.
Photo by Scott Bauer. (K8334-1)



In the next issue!
> One of the biggest ARS cooperative research and
development agreements in history could soon enable farmers to
click a computer mouse for a bird's-eye view of their fields and
crop health.
I Taiuia-it's a potent feeding stimulant that drives some
insects wild-and it could be just the right ingredient to make
pest-control formulations irresistible.
) Now that scientists know which bacterial strains produce
antibiotics powerful enough to stop wheat take-all in its tracks,
they're trying to exploit this natural biological control in U.S.
wheatfields.


Agricultural Research/February 1999








L n au*



Experiments set up in 1931 have helped chronicle the history of farming in the Pacific Northwest.


H ot, dry, and windy. That descrip-
tion might not bring Oregon to mind. But
some parts of the Columbia Plateau on
the eastern side of Oregon's Cascade
Range receive less than 10 inches of pre-
cipitation annually-compared with 60
inches on the verdant AUER (K8329-2)
western side of the
slopes and nearly 200
inches in the coastal
mountains.
The soil in this dry
region of the North-
east is among the
most fertile in the na-
tion. It was left be-
hind by glaciers, then
swirled by wind and
redeposited up to 150
feet thick. The pla-
teau rings an ancient
lakebed stretching
from the Cascades
east to Idaho, and
from northeastern
Oregon to Canada.
The area produc-
es the lion's share of Amy Baker, a biolo
the nation's soft records water dept]
white wheat crop, with an electronic c
worth more than $1 infiltration studies
billion annually. Soft
white wheat is pre-
ferred for Asian noo-
dles and confections.
To help wheat
growers stay competitive in the future,
scientists are looking to the past.
The Columbia Plateau Conservation
Research Center in Pendleton, Oregon,
manages some of the longest running ag-
ricultural experiments on cultivated land
in the western United States. The center
is managed cooperatively by the Agri-
cultural Research Service and Oregon
State University.


gic
hmr
:ali
on


Settlers first began farming here in the
late 1870s. By the early 1900s, lower
yields and erosion were already problems.
The Pendleton experiment station was es-
tablished in 1928 to provide practical so-
lutions.
Wheat planted
in October takes
advantage of win-
ter rain and snow.
From April until
the August harvest,
the crop relies
mostly on water
stored in the soil.
Even so, many ar-
eas are too dry to
support a crop ev-
ery year. To con-
serve water, the
standard practice
has been to grow
wheat 1 year and
leave the land un-
planted, or fallow,
the next.
But this causes
al science technician, other problems.
measurements made With rain and melt-
per during ing snow on frozen
no-till plots. soil-and slopes
greater than 25 per-
cent in some ar-
eas-the region
has some of the
country's worst
erosion problems. And one of the most
important measures of soil quality-soil
organic matter-has declined up to 40
percent since farming started.

Taking a Long View
Experiments set up in 1931 help chron-
icle the history of farming in this region
and now give scientists a unique resource
for setting the best future course.


"These research plots give us a base-
line for comparison that we could achieve
in no other way," says ARS soil scientist
Paul E. Rasmussen. "And studies to iden-
tify sustainable management practices
and potential climate changes have cre-
ated international interest in the experi-
ments," he says. Rasmussen served as
chair of the committee that oversees the
experiments until 1997. He retired in early
1999 but still collaborates with the lab.
The Pendleton experiments include:
Grass Pasture: This 150- by 360-
foot plot was taken out of crop produc-
tion in 1931 and represents lightly grazed
grassland.
Continuous Cereal: Three adjacent
plots have been planted with cereal grains
every year since 1931 as a comparison
for other crop rotations. The crops grown
have changed over the years and now
include winter wheat, spring barley, and
spring wheat. The soil is conventionally
tilled with a moldboard plow.
Residue Management: This exper-
iment represents the typical farming tech-
niques used in the region. In this block of
plots, winter wheat has been alternated
with fallow since 1931. Nine 38- by 132-
foot plots receive different treatments,
such as burning the wheat stubble in the
fall, burning in the spring, or applying
different amounts and types of nitrogen.
All are conventionally tilled.
Tillage-Fertility: Established in
1940, this experiment is also winter
wheat/fallow, but it compares different
types of tillage, including moldboard
plow, chisel plow, and sweep tillage.
Nitrogen applications also vary.
Wheat/Pea: Since 1963, winter
wheat has been alternated with a pea crop
in this experiment to determine the via-
bility and nitrogen needs of a wheat/le-
gume rotation. These plots use four
different tillage systems.


Agricultural Research/February 1999












.
*- *. .. ..: .. ...." .--.. : %:.. .7' -.-' -- ^..


. ,' '** "' -" -'"' 4w. . ." .-p"_ 4-' *.
i -,-' r A' t... -. 'At"t %^ ...ri. t "^i-
.4 --_.,
~~ ~7
kiq
Vp :~~


*No-Till Wheal: Thi e\pernent. .set
up in 192. analh zes \ heat field and soil
quality in a no-till \ inter \ heal/tallow
s\ teln. In 197. ,. identical _et of plots
\\ set uIip 50 that scientists could see hot\
the moil and crop \ ariables change % hen
land i, con erred rom con\ entional till-
age to no-ttill-alsotcalled direct seeding.

\\hal the Research Tells [is
Data collected m\er 0 decade, lho\\
that grain \ field has nearly\ doubled sincee
the 193(k.. thanks to improvements in
\ heat arterieses and soil fentilit in nage-
mneni.
The traditional farming \ stei inclu'd-
ed allow ing e\ er other \ear and tllliinI
\ ith a moldboard plo\\. But the \peri-
menlts sho\\ed that tile long-terin II\i-
rornmelntal costiI ,lthese practices is high.
The s\ tern lea\ es the land vulnerablee
lo \\ nd and \\ aercrosion that can\ a\\ a\
the nrutrient-rich soil and require larnlers
to add increasing arnounisof nitlocen fer-
tili/er. In fact. the ,ame varietiess that
pro\ ide higher field % need liuch more
nitrogen. \\ heat crops in the I 9-u.i used
15 pounds of nitrogen per acre: b\ the
1980s, they required 80 pounds.
Adding ammonium-based fertilizer
also causes problems, such as increased
soil acidity, which requires yet another
additive-lime-to raise the soil's pH.
This added cost puts even more pressure
on farmers struggling to survive when
wheat prices are low.
Part of the answer is to retain or im-
prove soil organic matter. Organic mat-
ter represents the part of the soil formed
by decomposition of carbon-based life:
mostly plants and microscopic organisms.
The rest of the soil is made up of sand,
silt, and clay. Without added inorganic
fertilizers, plants derive most of their nu-
trients, including nitrogen and sulfur,
from the organic matter.

Agricultural Research/February 1999


'a -; `,












SCOTT BAUER (K8330-2)


"When farmers started growing wheat
on the Columbia Plateau, they didn't re-
alize the importance of soil organic mat-
ter," says ARS microbiologist Steve L.
Albrecht, who now manages the ARS
conservation studies. "These experiments
are showing us the best methods to eval-
uate and maintain soil quality."
Farmers and scientists have known for
years that leaving the straw residue from
the previous crop on the surface reduces
erosion by holding the soil in place. The
long-term no-till experiment has shown
that seeding directly into this residue
without tilling also helps improve soil
quality over time.
But previous attempts at no-till direct
seeding largely failed because weeds were
harder to control, wheat diseases were
severe, and capital costs for new equip-
ment were high.
"Farmers didn't know what to expect
when they tried to convert to no-till, and
many were unsuccessful," says Albrecht.
But environmental conditions and rising
production costs are forcing the issue, cre-
ating renewed interest in no-till.
"We've shown that water infiltration
and earthworm activity increase dramat-
ically soon after switching to no-till," he
says. "That reduces erosion and increas-
es water availability to crops."
Soil organic matter also increases-
but very slowly, over long periods of time.

What's New at Pendleton
The newest experiment duplicates the
no-till plot established in 1982. The sci-
entists' goal is to precisely monitor chang-
es to soil quality and other crop variables
as a field is converted from conventional
tillage to direct seeding. "That way, farm-
ers won't have any surprises," Albrecht
says.
The experiments have also been in-
cluded in several international studies,
many of even longer duration.
"The nonirrigated, semiarid nature of
the Columbia Plateau mirrors other areas
of the world that have no such experi-
ments," says Rasmussen. "So even


though the experiments aren't as long-
term as some, they appeal to research-
ers looking at global trends."
Most of the current team of Pendle-
ton scientists, as well as many retired
ARS and university scientists, have
worked on the plots since their incep-
tion. But much of the credit for their
ongoing success and international rep-
utation goes to ARS' Rasmussen.
When he arrived in 1971, he quick-
ly became interested in the long-term
research, but he realized that many of
the records were in disarray.
"The long-term plots were well
maintained, but not much analysis had
been done," says Rasmussen.
OSU plant pathologist Richard W.
Smiley, superintendent of the station,
agrees. "For many years, funding


In a long-term no-till experiment, soil
scientists Clyde Douglas and Paul
Rasmussen use a recording penetrometer to
collect soil strength measurements.


SCOTT BAUER (K8329-1)


Biological science technician Amy Baker
and soil scientist Ron Rickman evaluate
soil waler inillration in an experiment set
up in 1982 to study the long-term effects of
no-till production on soil quality and wheat
3ield.












SCOTT BAUER (K8330-1)


A portable infrared gas analyzer
allows ARS microbiologist Steve
Albrecht to measure soil respiration.


sources wanted to focus on research with
more immediate benefits. That drew
many scientists away from the longer term
projects," he says.
The emphasis on short-term research
worried Rasmussen.
"The conclusion you reach in the short
term may not be appropriate over a long-
er period of time," he says. "When you
drastically change a farming system, it
takes time to reach a new equilibrium. If
you only take a snapshot look at a chang-
ing system, the view could be completely
different from what it will look like when
it stabilizes."
Rasmussen assumed the task of orga-
nizing the data and trying to fill in the
gaps. Although this project was not with-
in his assigned scope of investigation, he
devoted months of nights and weekends
to this effort until it became an official
part of his job.
Since then, he's set up a committee to
oversee the experiments. The goal is to
make changes necessary to meet the needs
of the research and farming community


lT cs










o r i


SCOTT BAUER (K8336-1)


Amy Baker, a biological science technician,
catalogs and archives soil samples taken
from long-term experimental test plots.


while ensuring that the value of the data
is not compromised.
"It's hard to say what the future of the
experiments would have been if Paul
hadn't taken an interest," says Smiley.
"He was the right person at the right time
to keep those experiments moving for-
ward."-By Kathryn Barry Stelljes,
ARS.
This research is part of Soil Resource
Assessment and Management, an ARS
National Program described on the
World Wide Web at http://www.nps.ars.
usda. gov/programs/202s2.htm.
Steve L. Albrecht is at the USDA-ARS
Columbia Plateau Conservation Re-
search Center, P.O. Box 370, Pendleton,
OR 97801-0370; phone (541) 278-4392,
fax (541) 278-4372, e-mail stephan.
albrecht@orst.edu. *







Just Off Press
A new, 32-page ARS publica-
tion, Low-Input On-Farm Com-
posting of Grass Straw Residue
(No. ARS-142), by Donald B.
Churchill, W.R. Horwath, L.F. El-
liott, and D.M. Bilsland, explains
the effects that various compost-
ing procedures have on reducing
straw volume. These procedures
provide a necessary alternative to
open field burning, which is be-
ing phased out in many regions
through legislative mandates. The
publication is available free of
charge (while supplies last) from
Donald Churchill, USDA-ARS,
National Forage Seed Production
Research Center, 3450 S.W. Cam-
pus Way, Corvallis, OR 97331-
7102.


Agricultural Research/February 1999



























In the soybean genome project, geneticist Perry Cregan examines the most current version
of the plant's integrated genetic linkage map.


There's Treasure in the

Soybean Genome Map


T he soybean has three fewer
pairs of chromosomes and
about 1.7 billion fewer pieces
ofDNA units than humans. But
Perry B. Cregan has shown that
the same scientific tools can be used to
draw the map of both the soybean and
human genomes.
Cregan is a plant geneticist with the
Agricultural Research Service in Belts-
ville, Maryland. The United Soybean
Board has given him and colleagues else-
where in the country more than $1 mil-
lion to construct a map of the soybean
genome using a technique from the hu-
man genome project called SSRs-sim-
ple sequence repeats.
This approach allows Cregan to look
at the smallest pieces of DNA in each of
the soybean's 20 pairs of chromosomes
that contain a total of 1.3 billion bases, or
units. Each base is represented by a sin-
gle letter of the DNA alphabet: A-G-C-
T, for adenine, guanine, cystosine, and
thymine.


Cregan and colleagues use SSRs to
find unique variations in these pieces that
can serve as markers for nearby genes.
With earlier technology from the human
genome project, they mapped the broad
outline of all 20 pairs of the soybean's
chromosomes.
So far, they've found more than 700
SSR markers from within these 20 chro-
mosome pairs. Now they're filling in the
details-one unit at a time-with a new
type of DNA marker, SNP (for single
nucleotide polymorphism). There are an
average of 65 million bases per chromo-
some, says Cregan. "Ideally, we'd like to
have an SNP marker every 100,000 to
250,000bases." SNPhas greatly increased
the rate of DNA marker discovery.
Cregan is actually working with three
other teams of scientists, each of which
has a different genetic map because each
uses different soybean varieties. And a
fourth map is in the offing.
Cregan's ARS colleague, Randy C.
Shoemaker, is leading a team of research-


ers that has developed a map at Iowa State
University. Researchers at the Universi-
ty of Nebraska at Lincoln and the Uni-
versity of Utah at Salt Lake City have the
other two maps.
The soybean mapping is part of a na-
tional public-sector initiative to map the
genomes of various crops and publicly
disseminate the results. To give the pub-
lic access, Cregan will e-mail the genetic
sequences of the 600-plus SSR markers
he has found to any researcher who re-
quests them.
The sequences are also available on
SoyBase, the USDA/ARS Soybean Ge-
nome Database developed under Shoe-
maker's leadership. To access them on
the World Wide Web, go to http://
129.186.26.94/
Why would the United Soybean Board
spend a million dollars to draw a map of
the soybean genome? One reason is a
projected additional 220 million bushels
of soybeans a year for American farmers
to sell on the domestic and international
markets. That's the number of bushels
robbed each year byjust one soybean pest,
the soybean cyst nematode.
Cregan's goal and that of a number of
other soybean researchers is to identify
genes that will provide resistance to the
soybean cyst nematode so the resistance
can be bred into commercial soybean
varieties. Cregan has completed the de-
velopment of mapping markers for the
first two of the four genes he thinks are
responsible. He's continuing work with
colleagues at the University of Minne-
sota to find markers for the remaining
two resistance genes.
Potential gains are huge for American
farmers. The extra 220 million bushels is
just for starters. Throw in another few
hundred million bushels for other pests
the soybean might also resist, were a com-
plete genome map available to plant
breeders. And yet another 200 million
bushels or so could be harvested, were
genes found to raise soybean yields 2 or
3 bushels an acre over America's typical
yearly plantings of 75 million acres.

Agricultural Research/February 1999







KEITH WELLER (K8347-11


Cregan and his colleagues are hoping
to find DNA fragments from the wild
ancestor of soybean that could induce
such a yield increase in commercial soy-
beans. He and the Nebraska team have
developed over 300 lines of soybeans that
have one-eighth of their genomes re-
placed by DNA fragments from the wild
ancestor of soybeans.
"If you could see the scrawny vine a
wild soybean is, with seed pods that hold
seeds not much bigger than poppy seeds,
you'd realize how unlikely it seems that
genetic material from the wild soybean
could be used to improve the beefy soy-
beans on the market today," says Cregan.
"Without DNA markers, it would be im-
possible to find just the right wild soy-
bean DNA fragments. But this SSR
genome map allows us to do a unit-by-
unit search for genetic benefits. It is what
gives our breeding efforts a reasonable


probability of success." .
And the maps will
make breeding easier
and quicker. "No long-
er will breeders have to
grow plants and expose
them to insects or plant
diseases to find the re-
sistant ones," says
Cregan. "They can use
the map markers to
identify the resistant DNA analysis sof
plants and only contin- fragment-size da
and biological lal
ue breeding the plants and Chuck Quigl
that have the genes they
want."-By Don Comis, ARS.
This research is part of Plant, Micro-
bial, and Insect Germplasm Conserva-
tion and Development, an ARS
National Program described on the World
Wide Web at http://www.nps.ars.
usda.gov/programs/301s2. htm.


tware aids examination of DNA sequence and
ta by visiting scientist Qijian Song (foreground)
)oratory technicians Chris Lee, Susan Fogerty,
y (rear).


Perry B. Cregan is at the USDA-ARS
Soybean andAlfalfa Research Laborato-
ry, Bldg. 006, 10300 Baltimore Ave.,
Beltsville, MD 20705-2350; phone (301)
504-5070, fax (301) 504-5728, e-mail
pcregan@nal.usda.gov. +


KEITH WELLER (K8340-1)


In one of the quality control steps in the
Public Soybean EST Project, geneticist
Randy Shoemaker evaluates DNA
sequencing reactions.


Public Soybean EST Project
Time-lapse photography reveals the beauty of a blooming flower in a dynamic way
that the human eye cannot perceive in real time.
Similarly, Agricultural Research Service scientists are taking "snapshots" of soy-
bean genes at different stages of genetic expression to capture a similar picture. The
objective is to identify genes in the soybean genome that are turned on, or expressed,
at different stages of plant development.
This approach will advance the scientists' ability to detect the differences in a gene
that is inactive versus when it is expressed. Results of the studies will be made
available worldwide via the Internet.
In the Public Soybean EST (Expressed Sequence Tag) Project, scientists will
attempt to identify all 80,000 genes in the soybean plant while they are turned on.
ARS geneticist Randy C. Shoemaker in Ames, Iowa, is the principal investigator
on the EST project. Lila O. Vodkin at the University of Illinois, Paul Keim at Northern
Arizona University, Ernest Retzel at the University of Minnesota, and scientists at
Washington University are co-investigators.
"We have two goals," says Shoemaker, who is based at ARS' Corn Insects and
Crop Genetics Research Laboratory in Ames. "One is to identify the structure of the
soybean genome and tag, or identify, the genes that make up that structure. Second,
we will identify the function of those genes and what they tell the plant to do."
A functional genetic map will give researchers more information on specific traits
and how to use them to develop new varieties.-By Dawn Lyons-Johnson, formerly
with ARS.
Randy C. Shoemaker is at the USDA-ARS Corn Insects and Crop Genetics Re-
search Laboratory, 1575 Agronomy Bldg., Iowa State University, Ames, IA 50011;
phone (515) 294-6233, fax (515) 294-2299, e-mail rcsshoe@iastate.edu.













oybeans are be-


coming aneconom-
ically important
crop in the Mid-
south. However,
many soybean crops don't
yield enough for growers to
make a decent profit. The
culprit: clayey soils.
Clay soils make up about
50 percent-some 9.5 mil-
lion acres-of the land in the
lower Mississippi River al-
luvial floodplain, which ex-
tends from Cape Girardeau,
Missouri, through Louisiana
to the Gulf Coast.
Farmers find these soils
often hard to manage. When
water is lacking, the clay
shrinks and cracks, damag-
ing the plant's existing root
system and subjecting it to
severe stress that shrinks
yield. Soybeans
Agricultural engineers
Richard A. Wesley and Low-
rey A. Smith, who are in the
ARS Application and Pro-
duction Technology Research P r
Unit at Stoneville, Mississip-
pi, have found the cure for
farmers' soybean blues. In
dryland production systems,
they found that using subsoiling-a type
of deep tillage-to a depth of 12 to 16
inches in the fall, when the soil profile is
dry, produces higher soybean yields.
Current recommendations for soybean
production on heavy clay soils call for
tillage down only to 4 to 6 inches.
"Clay soil is like building blocks
stacked together," says Wesley. "When
it dries, it forms a blocky structure with
large cracks between, representing the
weakest part of the soil profile. Deep till-
age breaks up and rearranges the struc-
tural blocks that occur below the surface."
With subsoiling, the tool penetrates
the soil's blocky structure, creating ar-
eas of loose soil and large pores without


ready for harvest.


3ubsoiling Boosts Yields

otects Soil in Clayey Are




disturbing crop residue on the soil sur-
face. Subsoiling allows water to infiltrate
the lower regions of the profile quickly,
where more is stored than would be with-
out subsoiling. This additional water-
holding capacity contributes to higher
yields and environmental bonuses: less
runoff, less erosion, and less sediment in
lakes and streams.
Most importantly, since subsoiling
doesn't destroy crop residues on the sur-
face and probably is not required every
year, the practice is compatible with con-
servation tillage.
In a 5-year study conducted on Tunica
clay with both optimal and extremely dry
seasonal weather, Wesley and Smith


A


Agricultural Research/February 1999


found that soybeans planted
in the deep-tillage system
without irrigation produced,
on average, 43 bushels per
acre-compared to a conven-
tional tillage system that pro-
duced 29 bushels without
irrigation and 45 bushels with
irrigation.
Net returns, however,
were $129 an acre from non-
irrigated deep tillage, com-
pared to $48 from
nonirrigated conventional
production and $83 from the
more costly irrigated system.
"This was a huge return for
soybean farmers," says Wes-
ley.
S Smith conducted similar
B studies with cotton, though it
I was previously thought that
I deep tillage ofclay soil plant-
B ed to cotton was not benefi-
cial.
"Many of those studies
were done in the spring when
s, the clay was still wet from
rain," says Smith. "Cotton,
0as like soybeans planted on fall
deep-tilled clay soil, also
makes significant yield im-
provements."
"This production practice
will give Midsouth farmers a chance to
produce a high-yielding crop on perceived
inferior soils," says Wesley.-By Tara
Weaver, ARS.
This research is part of Soil Quality
and Management, an ARS National Pro-
gram described on the World Wide Web
at: http://www.nps.ars.usda.gov/pro-
grams/202s2.htm.
Richard A. Wesley and Lowrey A.
Smith are in the USDA-ARS Application
and Production Technology Research
Unit, P.O. Box 36, Stoneville, MS38776-
0036; phone (601) 686-5354 [Wesley],
(601) 686-5355 [Smith], fax (601) 686-
5372, e-mail rwesley@ag.gov
lasmith@ag.gov. *










































IV ycotoxins are naturally occurring chemicals made
by fungi that can grow on corn, barley, wheat, and
other commodities.
One of these toxic chemicals, aflatoxin, is pro-
duced by Aspergillusflavus. It takes its greatest toll on U.S. corn
production during years when the crop has been subjected to
high temperatures and drought stress.
To safeguard human food and animal feed, U.S. law prohib-
its the sale of corn-or any grain-for human consumption if it
contains more than 20 parts per billion (ppb) of aflatoxin. For
domestic non-milk-producing animals, the permissible level
ranges from 100 to 300 ppb.
To detect these minute levels, purchasers, suppliers, and reg-
ulators must have accurate, sensitive tests.
"The lab tests that we now use to measure mycotoxins in corn
and other field crops are expensive and take many instruments
to accomplish," says Agricultural Research Service chemist Chris
M. Maragos, who is at the National Center for Agricultural
Utilization Research in Peoria, Illinois.
To speed up testing, Maragos has developed a new antibody
for an existing enzyme-linked immunosorbent assay. Known as
an ELISA test, it uses the new antibody to selectively bind to
aflatoxin, thereby improving the accuracy in detecting the toxin.
Maragos explains, "If there is no toxin for the antibody to
bind with, we see a deep orange color in the test solution. If there
is toxin present, we get a lighter color-or no color."


Diagra, Inc., a biotech company in Long Beach, California,
has entered into a cooperative research and development agree-
ment with ARS to further develop and market the new antibody
for an ELISA test kit.
A second tool Maragos uses to measure fungal toxins is
capillary electrophoresis. Electrically charged samples are pulled
through a thin, flexible straw called a capillary. This process
separates compounds based on their electrical charge and does
not require chemical solvents used by traditional analytical
methods.
With capillary electrophoresis, Maragos has improved the
sensitivity of testing to detect levels of aflatoxin in corn as low
as 0.5 ppb.
In 1998, Maragos adapted capillary electrophoresis to meas-
ure another type of mycotoxin-deoxynivalenol, commonly
called vomitoxin. This mycotoxin is associated with wheat scab,
a problem that's cost wheat growers around $3 billion in losses
over the last 3 years. After isolating the toxin, Maragos was able
to detect as little as 0.1 parts per million (ppm) deoxynivalenol
in wheat samples within 6 minutes.
He is now developing a new generation of detection methods
using a biosensor, another type of immunoassay; it uses anti-
bodies to trap and measure toxin levels. A series of lenses and
small optical fibers detects the toxin's light-blue fluorescence.
Although the current instrument is large, Maragos believes
it could be miniaturized and carried into the field to check crops
before harvest.
"We develop the methods to accurately measure mycotoxin
levels in food and feed and then turn the methods over to indus-
try so that they can help keep these toxins out of people's food,"
he says.-By Linda McGraw, ARS.
This research is part of an ARS National Program on Food
Safety, described on the World Wide Web at http://
www. nps. ars. usda.gov/programs/108s2. htm.
Chris M. Maragos is in the USDA-ARS Mycotoxin Research
Unit, National Center for Agricultural Utilization Research,
1815 N. University St., Peoria, IL 61604; phone (309) 681-
6266, fax (309) 681-6686, e-mail maragocm@mail.ncaur.
usda.gov. *


Agricultural Research/February 1999





NATIONAL ANIMAL DISEASE CENTER


Battling Food-Poisoning

Bacteria


In 1931, USDA's Bureau of Home
Economics published the fourth edi-
tion of Aunt Sammy's Radio Reci-
pes, a compilation of the most
popular recipes and menus from
"Housekeepers' Chats," a 1926 radio pro-
gram for women.
Today, USDA is still concerned with
the preparation of food. But the spotlight
now is on food safety rather than cook-
books-on doing everything possible to
make sure our food is safe and wholesome.
Every year, 6.5 to 33 million people in
the United States get foodborne illnesses.
The estimated medical costs and produc-
tivity losses range from $6 to $34 billion
a year. And the food industry loses mon-
ey-and product reputations-through
embargoes, recalls, and voluntary destruc-
tion of products.
For these reasons, the National Food
Safety Initiative was begun in 1997. It's a
comprehensive national program to im-
prove the safety of food all the way from
where food starts-on the farm-to where
it winds up-on your table. USDA carries
out the initiative along with the Food and


Drug Administration, Centers for Dis-
ease Control and Prevention, and U.S.
Environmental Protection Agency.
Across the country, Agricultural Re-
search Service laboratories at 10 loca-
tions are leading the scientific battle
against food pathogens in fresh and pro-
cessed meats, milk, grains, fruits, vege-
tables, and other foods. The work of just
one of these labs is profiled here-the
National Animal Disease Center
(NADC) in Ames, Iowa.
Researchers at Ames are battling four
major bacterial pathogens in food:
Campylobacterjejuni, Salmonella, Es-
cherichia coli 0157:H7, and Listeria
monocytogenes. One major battle is al-
ready won: finding faster ways to iden-
tify the enemy.
"Each strain of bacteria has a specific
genetic fingerprint," says ARS microbi-
ologist Irene V. Wesley. When an out-
break of foodborne illness occurs,
Wesley obtains samples of both the food
and bacterial isolates taken from indi-
viduals who became ill. Her basic stud-
ies show that DNA fingerprints of the


KEITH WELLER (K8338-1)


Microbiologist Irene Wesley examines the growth of microbes obtained from a hog carcass
swab. Her work is part of the National Food Safety Initiative, which has as a major goal
reducing foodborne pathogens on the farm and in foods.


Campylobacter requires complex media for
growth. Biological technician Sharon
Franklin searches a blood agar plate for
typical Campylobacter colonies.


patients' harmful bacteria match those in
foods that made them ill.
In the last 3 years, Wesley and her
NADC colleagues have developed sev-
eral quick and accurate tests to identify
foodborne pathogens. The tests use a
gene-multiplying technique called poly-
merase chain reaction (PCR) to recog-
nize pathogens in animal, human, and
food samples in less than 8 hours. Cultur-
ing techniques, by comparison, can take
up to 2 weeks.
Now the PCR tests are being put to the
ultimate test. Wesley and researchers at
Iowa and North Carolina State Universi-
ties are participating in a project funded
by USDA's Food Safety and Inspection
Service. They are tracking the spread of
Campylobacter, Salmonella, and Yersinia
enterocolitica in pigs-from the nursery
stage to slaughter. Usually kept in a sep-
arate facility, nursery pigs have been
weaned but are not yet developed into
what is called the grower stage.
The study, which includes eight farms
and two slaughterhouses, compares two
different ways of raising hogs in Iowa
and North Carolina. The results of this
study will be used to determine which
farm management practices reduce food-
borne pathogens.
With a PCR test, Wesley has shown
that 90 percent of nursery stage pigs har-
bor Campylobacter. At slaughter, the

Agricultural Research/February 1999







Researchers focus on four major food-

contaminating bacteria.


organism was found on 17 percent of hog
carcasses.
C. coli is a less severe pathogen than
its ugly relative-C. jejuni. The latter
organism is the leading cause of food-
borne bacterial infection in people. Four
million C. jejuni infections occur in hu-
mans each year in the United States, ac-
cording to the Centers for Disease Control
and Prevention.
Like twins that can trade places with-
out anyone knowing the difference, these
two microorganisms are difficult to tell
apart. But the PCR test is one of the best
ways to do it.
"Because they're so genetically simi-
lar, these two bacteria can exchange DNA
on the farm. Where C. coli exists, there is
also the probability that C. jejuni exists,"
says Wesley.
In another study, Wesley used the PCR
tests to identify C. coli in about 70 per-
cent of 1,300 market-weight hogs. Less
than 1 percent of the test hogs harbored
C. jejuni. Neither strainof Campylobacter
was detected in 29 percent of the hogs
sampled.

Keeping an Eye on Cleanliness
Public concern over E. coli 0157:H7
has skyrocketed since 1993, when the
microbe-in undercooked hamburger
patties-killed four children in the Pa-
cific Northwest. In that single outbreak,
477 people were infected from the un-
dercooked, contaminated hamburger.
Foodborne disease-causing bacteria
such as E. coli 0157 :H7 are found in feces
and spread to food through fecal contam-
ination. One of the prime ways to reduce
bacterial contamination is to reduce fe-
cal contamination in livestock and poul-
try slaughter facilities. Current federal
regulations mandate zero tolerance for
visible fecal contamination and for E. coli
0157:H7.
At the slaughterhouse, visual inspec-
tions and carcass cleaning have been two
of the standard tools for reducing the like-
lihood of E. coli and other bacterial con-
taminants in meat.


But "the human eye is not very sensi-
tive and often can't tell the difference
between feces and blood clots that can be
on a carcass," says ARS microbiologist
Mark A. Rasmussen at Ames.
Now Rasmussen, ARS microbiologist
Thomas A. Casey, and Iowa State Uni-
versity photochemist Jacob W. Petrich
have invented a new prototype instrument
based on fluorescent spectroscopy.
"We think this instrument has the po-
tential to greatly improve the ability of
inspectors to identify small amounts of
fecal contamination not detected visual-
ly on carcasses," says Casey.
The technology uses specific wave-
lengths or colors of light to illuminate the
carcass. Collected light returned from the
carcass is electronically analyzed to de-
termine if the carcass is contaminated.
The results are displayed as a numerical
value relative to the amount of feces. A
contaminated carcass would then be
trimmed or sanitized to remove the fecal
contamination.
Instruments can be designed to meet
the needs of any slaughter facility. They


could range in size from a portable, hand-
held device similar to metal detector
wands used at airports to a larger device
capable of detecting fecal contamination
on an entire carcass.
The researchers have applied for a
patent on the instrument and are con-
structing and testing other prototype
designs. About 60 companies and indus-
try organizations have contacted the
researchers. ARS plans to choose an
industry partner for a cooperative research
and development agreement to develop
the prototype into a commercial instru-
ment.-By Linda McGraw, ARS.
This research is part of an ARS Na-
tional Program on Food Safety described
on the World Wide Web at http://www.
nps. ars. usda. gov/programs/109s2. htm.
Scientists mentioned in this story are
at the USDA-ARS National Animal Dis-
ease Center, P. O. Box 70, Ames, IA 50010;
phone (515) 663-7200, fax (515) 663-
7458, e-mail
wesley @ nadc. ars. usda. gov
mrasmuss @ nadc.ars. usda.gov
tcasey@nadc.ars.usda.gov. *


Microbiologists Tom Casey (left) and Mark Rasmussen evaluate a new laser for use in their
fecal contamination detection system for meat carcasses. They are working in the laser lab
of an Iowa State University collaborator, photochemist Jacob Petrich.


Agricultural Research/February 1999





















































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i"
~~
lit*ru ir.
tt~-~-
`"''

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~~t.r


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Can Foods Forestall Aging?

Some with high antioxiarit activity appear to aid memory


KEITH WELLER (K8351-1)


S studies at the Jean Mayer USDA
Human Nutrition Research Cen-
ter on Aging at Tufts University
in Boston suggest that consum-
ing fruits and vegetables with a
high-ORAC value may help slow the
Caging process in both body and brain.
ORAC-short for Oxygen Radical Ab-
sorbance Capacity-measures the abili-
ty of foods, blood plasma, and just about
any substance to subdue oxygen free rad-
icals in the test tube.
Early evidence indicates that this an-
tioxidant activity translates to animals,
protecting cells and their components
from oxidative damage. Getting plenty
of the foods with a high-ORAC activity,
such as spinach, strawberries, and blue-
berries, has so far-
raised the antioxidant power of hu-
man blood,
prevented some loss of long-term
memory and learning ability in middle-
aged rats,
maintained the ability of brain cells
in middle-aged rats to respond to a chem-
ical stimulus, and
protected rats' tiny blood vessels-
capillaries-against oxygen damage.
These results have prompted Ronald
L. Prior to suggest that "the ORAC meas-
ure may help define the dietary condi-
tions needed to prevent tissue damage."
Prior is coordinating this research with
Guohua (Howard) Cao, James Joseph,
and Barbara Shukitt-Hale at the Boston
center.
Science has long held that damage by
oxygen free radicals is behind many of
the maladies that come with aging, in-
cluding cardiovascular disease and can-
cer. There's firm evidence that a high
intake of fruits and vegetables reduces
risk of cancer and that a low intake raises
risk. And recent evidence suggests that
diminished brain function associated with
aging and disorders such as Alzheimer's
and Parkinson's diseases may be due to
increased vulnerability to free radicals,
says Joseph, a neuroscientist.
Such evidence has spurred skyrocket-


Neuroscientist Jim Joseph and behavioral
psychologist Barbara Shukitt-Hale
estimate the memory capacity of test rats
required to swim to a submerged platform
in a pool. Software quantifies their
performance by tracking swimming
patterns.


ing sales of antioxidant vitamin supple-
ments in recent years.
But several large trials testing individ-
ual antioxidant vitamins have had mixed
results. "It may be that combinations of
nutrients found in foods have greater pro-
tective effects than each nutrient taken
alone," says Cao, a chemist and medical
doctor.
For example, foods contain more than
4,000 flavonoids. These constitute a
major class of dietary antioxidants and
appear to be responsible for a large part
of the protective power of fruits and veg-
etables, Cao says.
By the year 2050, nearly one-third of
the U.S. population is expected to be over
age 65. If further research supports these
early findings, millions of aging people
may be able to guard against diseases or
dementia simply by adding high-ORAC
foods to their diets. This could save much
suffering, as well as reduce the staggering
cost of treating and caring for the elderly.


Cao developed the ORAC test while
he was a visiting scientist at the National
Institute on Aging in Baltimore, Mary-
land. After joining Prior's group 5 years
ago, the researchers assayed commonly
eaten fruits, vegetables, and fruit juices
with ORAC. [See "Plant Pigments Paint
a Rainbow of Antioxidants,"Agricultur-
al Research, November 1996, pp. 4-8.]
"The ORAC value covers all the anti-
oxidants in foods," says Cao. "You can-
not easily measure each antioxidant
separately," he adds. "But you can use
the ORAC assay to identify which phy-
tonutrients are the important antioxi-
dants."
The researchers have been testing
whether antioxidants other than vitamins
are absorbed into the blood and protect
the cells. And the results look promising.

It's in the Blood
Several laboratories have reported that
people can absorb individual flavonoids
thought to have protective powers. Prior
and Cao now have good evidence that
food antioxidants not only are absorbed,
they boost the antioxidant power of the
blood.
In an earlier study at the Boston cen-
ter, 36 men and women ranging in age
from 20 to 80 had doubled their fruit and
vegetable intake. According to the par-
ticipants' responses on a food frequency
questionnaire, they averaged about five
servings of fruits and vegetables daily
during the year before the study. That
intake was doubled to 10 servings of fruits
and vegetables daily during the study.
To estimate ORAC intakes for the
participants, the two researchers matched
the questionnaire and the diet data with
their own antioxidant values for each fruit
and vegetable. Before the study, says
Prior, the participants averaged 1,670
ORAC units daily. Increasing their fruit
and vegetable intake to 10 a day raised
the ORAC intake to between 3,300 and
3,500 ORAC units-or about twice the
previous antioxidant capacity.
Based on the participants' blood sam-


Agricultural Research/February 1999













pies, the antioxidants were absorbed. The
ORAC value of blood plasma increased
between 13 and 15 percent on the exper-
imental diet. This supports results of a
preliminary study in which Prior and Cao
saw a 10- to 25-percent rise in serum
ORAC after eight women ate test meals
containing high-ORAC foods, red wine,
or vitamin C. They tested red wine be-
cause it has a high ORAC value-higher
than white wine-and has been associat-
ed with a lower risk of cardiovascular
disease.
Ten ounces of fresh spinach produced
the biggest rise in the women's blood
antioxidant scores-even greater than
was caused by 1,250 milligrams of vi-
tamin C. An 8-ounce serving of straw-
berries was less effective than vitamin C
but a little more effective than 9.6 ounces
of red wine.
Prior says the increase in plasma
ORAC can't be fully explained by in-
creases in plasma levels of vitamin C,
vitamin E, or carotenoids, so the body
must be absorbing other components in
these fruits and vegetables. The antioxi-
dant capacity of the blood seems to be
tightly regulated, he says. Still, "a signif-


TOP ANTIOXIDANT FOODS
[ORAC* units per 100 grams**]
FRUITS VEGETABLES
Prunes 5,770 Kale 1,770
Raisins 2,830 Spinach 1,260
Blueberries 2,400 Brussels sprouts 980
Blackberries 2,036 Alfalfa sprouts 930
Strawberries 1,540 Broccoli florets 890
Raspberries 1,220 Beets 840
Plums 949 Red bell pepper 710
Oranges 750 Onion 450
Grapes, red 739 Corn 400
Cherries 670 Eggplant 390
Oxygen Radical Absorbance Capacity
About 3.5 ounces


icant increase of 15 to 20 percent is pos-
sible by increasing consumption of fruits
and vegetables, particularly those high in
antioxidant capacity."
The ORAC values of fruits and vege-
tables cover such a broad range, he adds,
"you can pick seven with low values and
get only about 1,300 ORAC units. Or,
you can eat seven with high values and
reach 6,000 ORAC units or more. One
cup of blueberries alone supplies 3,200
ORAC units.
Based on the evidence so far, Prior and
Cao suggest that daily intake be increased


Fruits with high oxygen radical absorbance capacity are freeze-dried by technician
John McEwen for feeding in experimental rat diets.


to between 3,000 and 5,000 ORAC units
to have a significant impact on plasma
and tissue antioxidant capacity.

Rats High on ORAC
Rat studies are yielding even more sup-
port for high-ORAC diets. The animals
live only about 2 1/2 years total, so it's
possible to follow the effects of high-
ORAC foods on the aging process.
Joseph and Shukitt-Hale have been
testing extracts of strawberry and spin-
ach, along with vitamin E, in the rodents.
And some of their results wouldn't sur-
prise Popeye. A daily dose of spinach
extract prevented some loss of long-term
memory and learning ability normally
experienced by middle-aged rats. And
spinach was the most potent in protect-
ing different types of nerve cells in var-
ious parts of the brain against the effects
of aging.
The researchers started 6-month-old
rats on four feeding regimens. Two groups
got diets fortified with either strawberry
or spinach extract, one ate the diet con-
taining an extra 500 international units of
vitamin E, while a fourth got the unforti-
fied diet. Shukitt-Hale, a behavioral psy-
chologist, had already put a group of rats
through their paces to determine when
they begin to falter in memory and motor
function. She says the animals start to
lose motor function around 12 months
and memory at 15 months; the latter is
equivalent to a 45- to 50-year-old human.

Agricultural Research/February 1999













When the study rats reached 15
months, she had them doing gymnas-
tics-such as walking on rods and planks
and trying to stay upright on a rotating
rod-all tests of motor function. She also
had these excellent swimmers paddle
around a deep pool until, using visual
cues, they found a submerged platform
on which they could rest. With this test,
she measures changes in long- and short-
term memory.
"None of the diets prevented motor
loss," says Shukitt-Hale. The 15-month-
old rats performed like middle-aged an-
imals whether they got the extra
antioxidants or not. But the spinach-fed
rats had significantly better long-term
memory than the animals getting the con-
trol diet or the strawberry-fortified diet.
They remembered how to find the hid-
den platform better over time, she says,
showing they retained more of their learn-
ing ability. The vitamin E-fed rats were
somewhat less protected against memo-
ry loss than the spinach group.
"That's significant," she notes. "It's
really difficult to effect a change in be-
havior."

Where Aging May Reside
Joseph looks for age-related changes
in brain cell function, focusing on an area
of the brain that controls both motor and
cognitive function-the neostriatum. As
people and animals age, the cells become
sluggish in responding to chemical stim-
ulation, he says. For 15-month-old rats,
the striatal cells have lost 40 percent of
their ability to respond to such signals.
Not so in the animals whose diets were
fortified with spinach or strawberry ex-
tracts or vitamin E. Their striatal cells
performed significantly better than those
of rats on the control diet-especially the
rats getting the spinach extract. That
group scored twice as high as the control
animals in Joseph's test.
The spinach group also scored best
among the fortified diets in a test of nerve
cells in the cerebellum, a part of the brain
that maintains balance and coordination.


The test was done by Paula Bickford, a
collaborating pharmacologist with the
University of Colorado Health Sciences
Center in Denver.
Why spinach is more effective than
strawberries is still a mystery. The
researchers conjecture that it may be due
to specific phytonutrients or a specific
combination of them in the greens. While
this research is still in its infancy, says


ORAC, blueberries are one of highest in
antioxidant capacity.
In human terms, says Prior, the ani-
mals got the equivalent of 3,000 ORAC
units. "If we can show some relationship
between ORAC intake and health out-
come in people, I think we may reach a
point where the ORAC value will become
a new standard for good antioxidant pro-
tection."-By Judy McBride, ARS.


To better understand cellular activity within the brain, technician Derek Fisher views
fluorescent images of calcium in cells that are affected by oxidative stress. The calcium
binds to a fluorescent dye that the imaging system can measure.


Joseph, "the findings, so far, suggest that
nutritional intervention with fruits and
vegetables may play an important role in
preventing the long-term effects of
oxidative stress on brain function."
Prior and Cao also have early evidence
that these foods protect other tissues. Sub-
jecting rats to pure oxygen for 2 days nor-
mally damages cells lining the tiniest
blood vessels, or capillaries, causing them
to become leaky.
As a result, fluid accumulates in the
rats' pleural cavity-the space surround-
ing the lungs. But that was minimized
when the animals were fed blueberry ex-
tract for 6 weeks before the oxygen stress.
Of all the fruits and vegetables tested with


This research is part ofHuman Nutri-
tion Requirements, Food Composition,
and Intake, an ARS National Program
describedon the World Wide Web athttp:/
/www. nps. ars. usda. gov/programs/
108s2.htm.
Ronald L. Prior, James A. Joseph,
Guohua Cao, and Barbara Shukitt-Hale
are at the USDA-ARS Human Nutrition
Research Center on Aging at Tufts Uni-
versity, 711 Washington St., Boston, MA
02111; phone (617) 556-3310,fax (617)
556-3299, e-mail
prior@hnrc.tufts.edu
josephne@ hnrc.tufts.edu
cao_am @ hnrc.tufts.edu
hale_ne@hnrc.tufts.edu. *


Agricultural Research/February 1999







MELONS


T hanks partly to modern interna-
tional shipping and handling,
fresh melons are no longer just
seasonal delights. They can now
be eaten year round-and Agri-
cultural Research Service studies to im-
prove their postharvest care may increase
their appeal even more.
Scientists at the ARS Subtropical
Agricultural Research Center in Weslaco,
Texas, and at the Children's Nutrition
Research Center in Houston, Texas, have
worked out a way to extend the market
life of melons. They give them a soaking
in a special calcium solution during the
time it takes to cool them right after har-
vest.
The dunking could allow growers to
provide sweet and tasty, vine-ripened
melons in greater quantities and to more
distant markets.
In laboratory and preliminary field
tests, the treatment prolonged market life
by at least 2 weeks. It also increased cal-
cium levels in the melons, especially hon-
eydews. Even without the treatment,
honeydews and cantaloupes are rich
sources of calcium, with a 1-cup serving
providing about 10 percent of an adult's
daily calcium needs.
But today's sweeter and more nutri-
tious varieties could become even better
as shippers adopt these new postharvest
handling procedures.
Could consumption of melons conse-
quently reach new highs? In 1997, per
capital consumption of cantaloupes, or
muskmelons, rose to 11.7 pounds, eclips-
ing the 11.2-pound record of 1946. To-
gether, all types of melons rank second to
bananas as the most-consumed fresh fruit
in the United States.

Why'd They Do It?
This melon research started with plant
physiologists Gene E. Lester at Weslaco
and Michael A. Grusak at Houston.
Previously, Grusak had developed
techniques for studying movement of
calcium from roots to edible portions of
vegetable plants, a first step toward de-


Are on a Roll
termining calcium bioavailability.
Lester had just completed a study
in which he found that certain cal-
cium solutions reduced tissue ag-
ing. So Lester, whose primary
research is aimed at extending the
shelf life of fruit in export mar-
kets, asked Grusak to help him de-
velop a way to increase calcium in
whole honeydew and cantaloupe
melons after harvest.
Lester knew that,just
as people need calcium
for strong bones, aging
melons-especially the
tissue associated with
the rind-need calcium
to maintain a degree of
firmness that protects
against spoilage. But in
ripe melons, calcium
steadily migrates from
the rind to the seeds, de-
pleting the rind of calci-
um needed for maintain-
ing cellular functions. e n,
Before the scientists
began work on a treat-
ment for whole melons,
they had to get an idea
of calcium concentra-
tions that might work
best. Grusak started by
first analyzing portions -
of melons, to learn
where calcium and mag-
nesium occur naturally. s -
Then, Lester grew
honeydews and canta-
loupes in a greenhouse
and submerged whole
fruits in solutions of
calcium chelated, or
ringed, with amino acid molecules, as well
as in non-calcium control solutions. He
then cut the fruits into millimeter sections,
from the rind to the seed cavity, and dried
them for shipment to Grusak's lab. Grusak
measured how much calcium was in each
section and then profiled how much
calcium had migrated through the melon


layers.
We did between 200
and 300 samples," says
Grusak.
"The calcium had a
much stronger effect in
t the honeydews than in
o cantaloupes, and we
think that may be
because of the canta-
e loupe's thick, spa-
ghetti-like outer net-
ting."
In cantaloupes,
about 10 days after the
fruit begins to form, tis-
sue technically known
as "lenticular" starts to
crack through the outer
rind to develop the ir-
regular netting. Honey-
dews, on the otherhand,
generally have no web-
bing and thus convey
calcium efficiently
through a normally un-
broken skin into the all-important adja-
cent green layer of the outer rind.
To confirm that cantaloupes' lenticu-
lar tissue was a problem, Grusak treated
small areas of whole melon surfaces with
the solution, but this time he labeled the
calcium with radioisotopes. This allowed
him to trace the nutrient's path through

Agricultural Research/February 1999






Calcium dips give vine-ripened melons added
nutrition, storability.


S;.the fruit. Using
;:, the radioisotopes,
.r he confirmed that
the calcium moved
more quickly through
'' the honeydew than
.. .through the cantaloupe.
; "' In this experiment, the
scientists treated freshly
trvested melons for 20 min-
uite in a 40-millimolar calci-
u in solution (1.6 grams of
c.,tciuiu per liter) chelated with
.inmIn acid. Within 24 hours, labeled
calcium in honeydew rind tissue mea-
sured about 24 percent of the labeled
calcium that was applied. In cantaloupes,
when the radioisotope was applied direct-
ly onto the lenticular tissue, the amount
of labeled calcium was less and vari-
able-9 to 12 percent.
The shelf life of vine-ripened honey-
dew and cantaloupe is generally about 7
to 12 days. Increased calcium in treated
greenhouse-grown honeydews at least
doubled their shelf life, Lester says.
The scientists found an application of
amino acid-calcium chelate solution with
at least 80 millimolar calcium (3.2 grams
per liter) was needed to appreciably ex-
tend the shelf life of whole honeydews or
cantaloupes grown in the greenhouse. Up
to 100-millimolar solutions are now in-
cluded in experiments begun last spring
with field-grown melons, which tend to
have thicker rinds.
"We want to find concentrations of cal-
cium that work best without harming
spring- and fall-grown melons, because
too much calcium canbe toxic to the mel-
on," says Lester.
Already the research has led to industry
interest. A major U.S. melon grower-
shipper, Starr Produce Co. of Rio Grande
City, Texas, is providing vine-ripened
melons for the research. According to
David LaGrange, manager of the
company's LaCasita Farms, vine-ripened
honeydews are really delicious but more
difficult to ship than those harvested as


Agricultural Research/February 1999


little as 3 days sooner. He says the calcium
treatment may help pave the way for
extensive marketing of vine-ripened
melons.
By planting recently developed hybrid
honeydews and harvesting them at full
maturity, growers could easily comply
with the federal law stipulating that mel-
ons destined for interstate commerce can
be harvested when their soluble solids
content reaches 9 percent. Hybrid mel-
ons detach themselves from the vine when
ripe, and as they do, the soluble solids
typically range from 12 to 15 percent-
almost totally in the form of sugars.
Melons treated to slow down soften-
ing could be shipped by surface transpor-
tation, rather than flown, halfway around
the world. Very sweet, unblemished,
green-fleshed melons have proven them-
selves popular, especially in Japan.-By
Ben Hardin and Jill Lee, ARS.
Gene E. Lester is in the USDA-ARS
Crop Quality and Fruit Insect Research
Unit, Kika de la Garza Subtropical Agri-
cultural Research Center, 2301 S. Inter-


national Blvd., Weslaco, TX 78596;
phone (956) 565-2647, fax (956) 565-
6652, e-mail glester@pop.tamu.edu.
Michael A. Grusak is at the USDA-
ARS Children's Nutrition Research Cen-
ter, 1100 Bates St., Houston, TX 77030;
phone (713) 798-7044, fax (713) 798-
7078, e-mail mgrusak@bcm.tmc.edu. +


It~a~'







Coping With Rett

Syndrome


A debilitating disorder that strikes

only girls, Rett Syndrome challenges

physicians, patients, and families.
One symptom of Rett Syndrome is profound growth failure.
Pediatrician and nutritionist Kathleen J. Motil with the USDA-
ARS Children's Nutrition Research Center (CNRC) in Hous-
ton, Texas, is finding innovative ways to promote adequate
nutrition, improve health, and enhance growth for some of these
patients.
Rett Syndrome occurs in 1 out of 23,000 live births. The
onset is baffling: A healthy, active infant gradually stops devel-
oping normally. Typically, she regresses, losing her speech and
walking skills, as well as the ability to play with toys. Repetitive
hand-wringing and hand-washing movements are common, as
are breathing abnormalities. Growth failure and muscle wast-
ing may occur as early as 1 year of age. Motil and others have
done studies suggesting this poor growth and wasting may be
linked in part to the girls' need for special nutritional care.
Andreas Rett, the medical doctor who first de-
scribed this neurodevelopmental disease in 1966,
noted the symptoms of wasting and slowed PAUL ViNC1
growth. Growth retardation is one of the factors
supporting the diagnosis of Rett Syndrome. Oth-
er researchers, including Motil's colleagues,
pediatric neurologist Daniel G. Glaze and nurse
practitioner Rebecca J. Schultz, have reported
in medical journals a deceleration in the rate
of gain in head circumference, height, and
weight.
Studies in Norway, England, and the
United States have suggested nutrition and
eating difficulties might be a possible cause
of these decreased rates of growth. Indeed,
"Part of the problem is that these girls
frequently have oromotor dysfunction,"
says Motil. "They don't chew or swal-
low properly, and their dietary intake is
inadequate to support normal growth." MoA1 IaW ui s
Motil has had some success fitting with mines a yo
her patients with a gastrostomy but- Y drome.g
ton, a surgically implanted device that
allows nutrients to be delivered into the body while
the girls sleep. One 7-year-old patient increased her weight
from 31 pounds to 48 in a year. She gained enough strength to
sit up by herself for the first time.
While that sounds like good news, an average 7-year-old
weighs about 60 pounds.
In addition to helping patients, Motil is doing research to find


out why these girls aren't growing and have less muscle mass
than their healthy counterparts.
Part of her research involves comparing the metabolism and
physiology of girls with Rett Syndrome to those of healthy girls.
For these experiments, small volunteer groups of girls with and
without Rett Syndrome spend brief stays at the General Clinical
Research Center at Texas Children's Hospital in Houston and
undergo tests at the neighboring CNRC.
Motil wondered whether the repetitive arm, hand, leg, and
body motions contributed to the development of malnutrition
by burning calories that would be otherwise used for growth.
Research she published in the February 1998 issue of Journal
ofPediatrics showed that repetitive motions were not an energy
drain.
But Motil noted that there were metabolic differences be-
tween the girls with Rett Syndrome and healthy girls. When
sleeping or resting quietly, those with Rett syndrome had total
body metabolic rates 23 percent lower than normal.
"The lower metabolic rate was caused by a lower lean-body
mass, or less muscle mass," said Motil. "The lower body mass
may be related to a lower dietary intake."
Although the energy balance of calories consumed, minus
calories used, was positive in girls with Rett Syndrome,
it was lower than that of age-matched,
healthy girls. It could be that a subtle,
long-running, energy-deficit diet ham-
pered nutrition and growth.
In a more recent study published as an
abstract in Pediatric Research, Motil add-
ed to evidence that giving girls with Rett's
syndrome a liquid nutritional supplement via
S the gastrostomy button was helpful. The test
showed it increased body weight and reversed
S the downward trend of poor growth in height.
: "Nevertheless, we found that the supple-
ments increased body fat much more than lean
body mass, even with the presumably adequate
protein and energy intake," said Motil. "Our next
task is to understand why we are unable to im-
prove muscle mass to the same extent as body
fat."-By Jill Lee, ARS.
Katleen This research is part of the ARS National Pro-
atient gram on Nutrient Requirements, Food Composi-
tion, and Intake described on the World Wide Web
at http://www.nps.ars.usda.gov/programs/
107s2.htm.
Kathleen J. Motil is with the USDA-ARS Children's Nutri-
tion Research Center, Department of Pediatrics, Baylor Col-
lege of Medicine, 1100 Bates St., Houston, TX 77030; phone
(713) 798-7178, fax (713) 798-7187, e-mail kmotil@bcm.
tmc.edu. *


Agricultural Research/February 1999


!








Sunflowers Add Variety to
the Great Plains


The land is desolate between wheat crops in the central Great
Plains. Traditionally, farmers leave the soil bare every other
year because there isn't enough water for an annual crop. The
average rainfall in this area is only 16.5 inches a year.
With the help of research, however, farmers are increasingly
finding ways to delay fallow to every third or fourth year.
They do this by leaving crop residues in place after harvest.
This reduces evaporation and stores more precipitation in the
soil for the next crop.
But crops need to be rotated to minimize disease and pest
problems. Sunflowers could be one of these new crops for the
central Great Plains, earning farmers money while protecting
soil from blowing away in spring winds that easily exceed 30
miles per hour.
David C. Nielsen, an agronomist with the Agricultural Re-
search Service in Akron, Colorado, finds that if sunflower stalks
are left about 30 inches high after harvest, they almost com-
pletely prevent soil loss. When the inevitable winter blizzards
arrive, the beheaded stalks act like snow fences, trapping 3 to 10
times more snow than would normally accumulate.
"When this snow melts, it replenishes 3 to 9 inches of soil
water," Nielsen says. "Depending on snowfall amounts and
wind speeds, this can recharge about 30 to 95 percent of the
water sunflowers use, making the practice worthwhile for farm-
ers. They should earn more money, even when yields of wheat
or other rotated crops are lower because of the water used by the
sunflowers."
Nielsen says sunflowers dry a soil out down to 6 feet in the
Great Plains. "But that's good because as the sunflowers use the
water that is too deep to be used by other crops, they also capture
nitrogen, reducing chances of groundwater pollution.
"While wheat may dry a soil down to 8 percent moisture by
volume, sunflowers dry it down to 3 or 4 percent," he says.
Nielsen has found that yields are best when sunflowers are
rotated in every 4 years rather than every 3. "We think that's
because growing sunflowers less frequently breaks disease and
pest cycles. And without disease, there's a greater chance of the
sunflower stalks standing up through the entire winter and next
spring."
Rotating in other crops like sunflowers also helps farmers
diversify.
"They're not so tied to weather conditions in a particular
year," Nielsen says. "This year's a good example. There was a
drought while winter wheat was growing. Then, wouldn't you
know it, it rained as soon as the wheat was harvested, and rain-
fall was better than average when the sunflowers were planted
and grown."-By Don Comis, ARS.
David C. Nielsen is at the USDA-ARS Central Great Plains
Research Station, P. O. Box 400, Akron, CO 80720; phone (970)
345-0507, fax (970) 345-2088, e-mail dnielsen@lamar.
colostate.edu. *


Topsoil Is Alive: Keep It Fresh




As anyone finds after moving into a newly built home, a yard
full of "sterile" subsoil is a poor substitute for healthy topsoil
when it comes to growing a lawn, shrubs, or a garden. Topsoil
brims with worms, microorganisms, and organic matter. Sub-
soil-material from below the topsoil-usually spells subpar
greenery.
Mining companies face a similar problem when reclaiming
strip-mined Western rangeland. But their problem is far more
serious: Federal and, often, state laws require them to replant
and establish native vegetation. New research points to a way
to give their efforts a better chance of success.
While rangeland vegetation like sagebrush may look tough,
it's delicate. The plants need all the help they can get from the
soil.
"Anything that helps plants tolerate drought is critical in the
arid and semiarid West, especially in disturbed, reclaimed soils,"
says soil scientist Gerald E. Schuman, who is with the Agricul-
tural Research Service. "Disturbing the soil-digging, piling,
spreading, and compacting it-destroys soil pores that hold
water."
Mining companies, he notes, typically salvage and store top-
soil as long as several years. They put it back only after they
finish mining a site.
But Schuman and colleagues at the University of Wyoming
at Laramie found that native vegetation is so needy that mining
companies should return topsoil no more than a few months
after it is removed.
Recently, the scientists learned why: Beneficial root-dwell-
ing fungi die off in topsoil stored too long. The fungi, called
mycorrhizae, have hairlike filaments that funnel water and nu-
trients to roots, helping plants survive drought.
The scientists learned about the mycorrhizae' s role in a green-
house study. The soil came from the site of a coal mine in
northeastern Wyoming. In fresh and sterilized batches of this
soil, they planted seed of Wyoming big sagebrush-a species
that must be replanted by mining companies if it was present
before disturbance.
The seedlings grown in fresh, fungi-rich topsoil survived 3
to 5 days longer when the soil was allowed to dry. "This could
be just the time needed to tide them over until the next rain,"
says Schuman, who is in the ARS Rangeland Resources Re-
search Unit at Cheyenne, Wyoming.
He recommends that topsoil stockpiling be limited to the
start of mining operations and for no more than a few months.
"After that it should, whenever possible, be salvaged and
respread where needed in a single process."-By Don Comis,
ARS.
GeraldE. Schuman is in the USDA-ARS RangelandResources
Research Unit, 8408 Hildreth Rd., Cheyenne, WY 82009-8899;
phone (307) 772-2433,fax (307) 637-6124, e-mail gschuman @
lamar.colostate.edu. *


Agricultural Research/February 1999







Weevil Gets Upper Hand With

Unruly Weed


JACK DYKINGA (K8318-1)


On a hillside in the Clearwater River valley
near Lewiston, Idaho, ARS entomologist
Steven Clement (right) and University of
Idaho entomologist Joseph McCaffrey
inspect yellow starthistle for evidence of
damage by Eustenopus villosus. Biological
control is starting to take hold in this area.


0i 00 right-yellow flowers
carpet canyon slopes
above the Clearwater
River in Idaho. But it's
a small, denuded patch
I that excites scientists.
| That's because the
flowers belong to the
noxious weed called
yellow starthistle, and the bare patch is
one of the first signs of success in the
biological control of the weed.
A small weevil, Eustenopus villosus,
gets credit for cutting the plant down to
size.
In their Eurasian homeland, insects and
disease organisms keep yellow starthis-
tle at low levels. But when the spiny weed
entered the United States in the mid-
1800s-probably in a hay shipment-it
found no natural enemies to hinder its
spread. Now the weed inhabits tens of
millions of acres in California, Idaho, and
other western states.
"When the thistle takes over areas like
river canyons, it displaces other vegeta-
tion and makes the land virtually worth-
less for livestock and wildlife," says
University of Idaho entomology profes-
sor Joseph McCaffrey. The weed is tox-
ic-sometimes fatal-to horses. Other
animals will eat only very young starthis-
tle plants.
Biological control of introduced weeds
has been an ongoing priority nationwide
for ARS. Preliminary work on yellow
starthistle began in the 1960s, but the
research program shifted into high gear
in 1983.
"We investigated several weevils and
flies that appeared to keep yellow starthis-
tle in check in its native habitat," says
ARS entomologist Stephen L. Clement,
who works at the Western Regional Plant
Introduction Station in Pullman, Wash-
ington. "Then we tested the insects at our
European facilities to make sure they
wouldn't feed on desirable plants in the
United States."
Since then, with approval from
USDA's Animal and Plant Health


Inspection Service, six of the insects have
been imported, and five have become
established. So far, the Eustenopus
weevil-imported in 1990-has been the
most effective.
After ARS scientists release the in-
sects, collaborators like McCaffrey mon-
itor and redistribute them to new sites.
"Fewer than 200 weevils were initially
released at Clearwater," McCaffrey says.
"Now we use the site as a nursery to col-
lect weevils for use in other weed-infest-
ed areas. We've moved at least 10,000
insects," he says.
Sites that show dramatic weed reduc-
tion are gratifying, but biological control
success is usually hard to measure.
"This weevil is valuable because it
attacks the weed twice," says ARS ento-
mologist Joseph K. Balciunas. Adults eat
developing buds. Females lay eggs in
older buds that remain, and the larvae that
hatch eat most of the seeds before they
mature.
However, in California, environmen-
tal conditions allow the weed to produce
more buds-and seeds- after the wee-
vils have completed their life cycle for
the year.
"Biological controls play an important
role in reducing the number of seeds the
weed produces every year," he says. "But
in some areas where plant numbers are
reduced, individual plants grow larger to
produce more seed."
To better understand the weed, Balci-
unas plans to compare its seed produc-
tion in the United States with that in
Turkey, where yellow starthistle is na-
tive. "The weed doesn't persist in its
homeland like it does here. If the soil there
is undisturbed, the weed disappears with-
in 5 years," he says. "If we can discover
why that happens, it will give us clues for
controlling the weed."-By Kathryn
Barry Stelljes, ARS.
Joseph K. Balciunas is in the USDA-
ARS Exotic andInvasive Weeds Research
Unit, 800 Buchanan St., Albany CA
94710; phone (510) 559-5975, fax (510)
559-5963, e-mailjoebalci@pw.usda.gov.

Agricultural Research/February 1999






------MM ------


'Pillars Fall to Poison Pill
Packaging a natural virus in an other-
wise appealing "poison pill" tricks de-
structive caterpillars into eating
themselves to death. The trickery offers
a natural way to control larvae of beet
armyworms, cabbage loopers, and other
moth pests. Normally, farmers combat
them with chemical insecticides. But ARS
scientists envision killing them with a
natural insect pathogen. The Anagrapha
falcifera nuclear polyhedrosis virus liq-
uefies the pests' tissues, while posing no
threat to beneficial insects, humans, or
wildlife. Researchers want to ensure that
the pests get a lethal dose, so they are
testing combinations of virus and feed-
ing stimulants. One concoction contains
cottonseed oil, sucrose, and other good-
ies irresistible to caterpillars like beet
armyworms that pester corn, cotton, and
cole crops.
In the greenhouse, scientists sprayed
collards with virus alone and mixed with
a feeding stimulant. Virus alone killed 57
percent of the larvae, but adding the feed-
ing stimulant doomed more than three-
fourths. In other tests, scientists sprayed
formulations containing fluorescent
brighteners. These help prevent light from
degrading the virus and improve its ca-
pacity to infect the pests. Only one-
fourth of armyworms survived on foliage
collected from outdoor collard plots
sprayed with virus and brightener. Twice
as many survived when the brightener
wasn't used. The scientists plan tests
combining all three ingredients-virus,
feeding stimulant, and brightener. Rob-
ert Farrar, Jr., USDA-ARS Insect Bio-
control Laboratory, Beltsville, Maryland;
phone (301) 504-5689, e-mail rfarrar@
asrr.arsusda.gov.

With New Tomatoes,
More Is Beta (Carotene)
Three new tomato breeding lines from
ARS hold 10 to 25 times more beta car-
otene than typical tomatoes. An ARS
plant geneticist bred the new tomatoes-
named 97L63, 97L66, and 97L97-for


t0re Zpdate



use in processing into paste, juices, and
sauces. High-beta-carotene cherry and
beefsteak tomatoes for the fresh market
are also on the way. The body converts
beta carotene to vitamin A. This essential
vitamin helps with vision, bone growth,
tooth development, and reproduction.
Content of beta carotene averages 57.6,
55.1, and 55.5 micrograms per gram of
fresh fruit for 97L63, 97L66, and 97L97,
respectively. This compares to only about
2 to 5 micrograms per gram for typical
tomatoes. Lines 97L63 and 97L66 are
adapted for California and Eastern and
Midwestern states; line 97L97, for the
East and Midwest. A major food compa-
ny is using material derived from the ARS
germplasm to develop nutritionally en-
hanced products. John Stommel, USDA-
ARS Vegetable Laboratory, Beltsville,
Maryland; phone (301)504-5583, e-mail
jstommel@asrr.arsusda.gov.

Corn Fungus Also Has a
No-Good Cousin
ARS scientists have discovered a cous-
in of the fungus that causes gray leaf spot
of corn. This means breeders must now
ensure that new corn hybrids resist both
forms of Cercospora zeae-maydis. A
severe infection can reduce corn yields
by 25 percent or more. The fungus first
turned up in this country in about 1925 in
Illinois. But it didn't become a serious
and widespread problem until the mid-
1980s, when more and more farmers
switched to tillage systems that leave crop
residue on the soil surface. That's because
C. zeae-maydis can overwinter in this res-
idue. In spring, the fungus produces
spores called conidia. Blown by wind or
splashed by raindrops, the conidia land
on leaves of newly emerged corn plants,
invade, and attack the plants' tissues. The
invasion may also make the plants weaker
and more susceptible to infection by oth-
er pathogens. Once a problem only in the
eastern part of the Corn Belt, gray leaf
spot now occurs as far west as Kansas
and Colorado. An ARS plant pathologist
found the new form of C. zeae-maydis in


the eastern part of the country. Scientists
are probing its genetic makeup to learn
more about its virulence. LarryD. Dunkle,
USDA-ARS Crop Production and Pest
Control Research Laboratory, West
Lafayette, Indiana; phone (765) 494-
6076, e-mail dunkle@btny.purdue.edu.

New Lure Could Take the
Sting Out of Some Wasps
An ARS entomologist has devised the
first effective lure for the German yel-
lowjacket, golden paper wasp, European
hornet, and other yellowjackets. Com-
mercial traps could be available in about
a year. Yellowjackets and wasps are oc-
casional nuisances for most people, but
they represent an occupational hazard for
fruit orchard workers during the picking
Season. Besides hurting, the
r stings can cause potentially
dangerous allergic reactions.
The new attractant may pro-
; vide a way to monitor and con-
trol the insects. It uses compounds that
bacteria and fungi make as byproducts of
sugar consumption. ARS has applied for
patent protection. Other baits-made
with sugar or meat-have drawbacks.
Sugary baits attract beneficial species,
such as honey bees. As for meat, it rots
too quickly to be practical in
a lure. Of 17 yellowjacket
species in the United States,
5 are significant, aggressive/
pests. The new lure is the first
to attract most of them, including the
German yellowjacket. It is also the first
chemical lure to attract paper wasps. The
scientist and Sterling International, Inc.,
of Veradale, Washington, are collaborat-
ing to develop a delivery system. The
work is being carried out through a co-
operative research and development
agreement. Peter J. Landolt, USDA-ARS
Yakima Agricultural Research Labo-
ratory, Wapato, Washing-
ton;phone (509)454-6551,
e-mail landolt@yarl.gov.


Agricultural Research/February 1999





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ARS maintains an extensive list of scientists with expertise related to
conservation and sustainable agriculture. To find locations where
research is under way or to contact scientists working in agronomy,
: hydrology, erosion control, composting, or other related areas, go
to http://www.ars.usda.gov/. Click on ARS Research and then
choose ARS Natural Resources and Sustainable Agricultural Sys-
tems Scientific Directory.













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