Group Title: Agricultural research (Washington, D.C.)
Title: Agricultural research
Full Citation
Permanent Link:
 Material Information
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
Publisher: Science and Education Administration, U.S. Dept. of Agriculture :
Science and Education Administration, U.S. Dept. of Agriculture :
Supt. of Docs., U.S. G.P.O., distributor
Place of Publication: Washington D.C
Publication Date: June 1997
Frequency: monthly[1989-]
bimonthly[ former jan./feb.-may/june 1953]
monthly[ former july 1953-198]
Subject: Agriculture -- Periodicals   ( lcsh )
Agriculture -- Research -- Periodicals   ( lcsh )
Agriculture -- Periodicals -- United States   ( lcsh )
Agriculture -- Research -- Periodicals -- United States   ( lcsh )
Genre: federal government publication   ( marcgt )
periodical   ( marcgt )
Statement of Responsibility: U.S. Department of Agriculture.
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.
General Note: Description based on: Vol. 27, no. 7 (Jan. 1979).
General Note: Latest issue consulted: Vol. 46, no. 8 (Aug. 1998).
 Record Information
Bibliographic ID: UF00074949
Volume ID: VID00007
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: ltuf - ABP6986
oclc - 01478561
alephbibnum - 000271150
lccn - agr53000137
issn - 0002-161X

Full Text

mlS V~vIs I 1
Ml 11 fiJf ,Cl


Diet Critical to
In this increasingly complex
world, the idea of relying less on
chemical pesticides and turning
instead to nature to help solve our
crop and livestock pest problems is
not only ideologically appealing, but
environmentally imperative.
However, to work most effectively
with nature to protect our crops and
animals, we need to use every mod-
ern scientific tool at our disposal.
Biological control of pests is a holis-
tic activity with several dimensions.
First, there's classic biological
control. Many of the pests that now
plague this country's crops and crea-
tures came from other parts of the
world; Columbus probably brought
house flies along when he set sail
from Spain in search of new lands. In
their homeland, these pests had natu-
ral parasite or predator enemies to
keep them in check. But in the New
World, there were no such limits.
To fight these crop and livestock
pests without routinely resorting to an
arsenal of chemicals, we must trace
their origins. For this reason, the Ag-
ricultural Research Service maintains
laboratories in France, South Amer-
ica, Australia, and China, where our
scientific explorers look constantly
for natural enemies of the pests that
have migrated to the United States.
But it's not enough simply to find
a natural enemy of our pest enemies.
Once we've collected these potential-
ly beneficial insects, they must be
tested rigorously to ensure that if
they're loosed against the pest
population, they won't turn next to a
crop for nourishment when the pest
supply is depleted.
Sometimes a natural enemy is
already present in this country to

combat a pest, but it exists in such
low numbers that it can't control the
pest to the degree we demand. Then
we use augmentation-that is,
rearing large numbers of the benefi-
cial insect to turn loose in the fields
or on the range.
This is a simple concept that's
anything but simple to accomplish.
It's not easy or inexpensive to mass-
rear biocontrol insects, especially
when you need to provide a host for
the young beneficial to eat. It means
you, theoretically, have to grow the
pest, too.
To circumvent this problem, ARS
scientists have put considerable
effort into developing artificial diets
to sustain our insect helpers, as
you'll read in this issue of Agricul-
tural Research ["Insects Get Fast-
Food," p. 4].
An insect responds to certain
cues-perhaps something it sees,
perhaps something it feels or
smells-to eat and to reproduce. We
have to identify those cues and learn
how to mimic them. It's not enough
to simply provide a diet that will
keep the beneficial alive; the diet
must help it to thrive and produce
multitudes of offspring. To meet the
needs for which nature typically
provides through the host insect, we
must have a thorough knowledge of
the biology and physiology of both
the insect we want to promote and
the insect we hope to control.
For example, many insects are
thought to suck liquid juices out of
their host's body, so scientists tried
making liquid diets. But the liquid
diets failed many times.
With more investigation, we've
now learned that when predatory
insects bite into their host, they inject
juices that partially digest the host's
body parts. If we provide the preda-
tors with a wholly liquid diet, their
injected juices can be lost in the
mixture-and thus aren't available

for use again in digesting the material
they ingest.
'We must use cutting-edge science
to unlock these secrets of nature, to
know exactly how an artificial diet
must taste, smell, and even feel. We
have to understand the beneficial
insect's needs if we are to produce
massive populations-not thousands
of insects, but millions-of these
natural enemies to fight our battles in
the field.
Even producing large numbers of
helpful insects isn't enough. We have
to ensure that our lab-raised benefi-
cials are strong enough to compete in
the wild, to hunt down and eradicate
our insect enemies. To make sure
we're not breeding that competitive-
ness out of our laboratory insect
populations, we have to conduct tests
to ensure the beneficial are suffi-
ciently aggressive.
As we work to build up popula-
tions of biocontrol insects, we must
also identify the proper measures
producers and others must take to
ensure that beneficial already in
place are protected. This is called
conservation-doing things to
properly manage the natural enemies
that inhabit an area. This often means
minimizing pesticide applications or
providing a habitat that protects the
beneficial from a harsh environment.
As you can see, there are many
parts to the equation for adapting
nature's methods to control crop and
livestock pests. Scientists have been
struggling with this multifaceted
problem for at least 30 years, but
only in the past 5 has technology
enabled us to make major strides in
producing excellent, cost-effective
artificial diets to mass-rear the
beneficial insects we need.

Raymond I. Carruthers
ARS National Program Leader
for Biological Control

Agricultural Research/June 1997

June 1997
Vol 45. No. 6
ISSN 0002-161X

4grciuliurail Researc is published monthly by
the Agncultural Research Service. li.S
Department of 4gnculiure. Washington. DC
The Secretary of Agriculture has determined
that thi6 periodical is necessary in the transac-
lion of public business required hb law.
Dan Glickman. Secretary
l S Department of Agriculture
Catherine Woek. .-cting Under Secretary
Research. Education, and Economics
Floyd P. Horn, Administrator
Agricultural Research Service
Robert W. Norton, Director
Information Staff
Editor: Llod McLaughlin 1301i 344-2514
Assoc. Editor: Linda McElreath i301 1344-2536
Art Director: William Johnson (301) 344-2561
Photo Editor- John Kucharski (301) 344-2900
Assoc. Photo Ed.: Anita Daniels (301) 344-2956
Information in this magazine is public proper,
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.
Subscription requests should be placed with
Ne Orders. Superintenendet of Documents.
P.O. Bo\ 371954. Pittsburgh. PA 1525(1-7954.
See back cover for order form.
Complimentary 1-ear subscriptions are
available to public lbraries. schools. employees
of the U.S. Department of Agriculture, and the
news media. Send requests or comments to:
Editor. Agricultural Research Magazine. Room
408. 6303 1%\ Lane. Greenbelt. MD 20770. E-
To isil Agriculural Research magazine on the
Internet. go to wu& .ars.usda.go\ and select
News and Information.
This magazine ma, report research in\ol ing
pesticides It does not contain recommendation,
for their use. nor does it impl) that uses dis-
cussed herein have been registered. All uses of
pesticides must be registered by appropriate
state and/or federal agencies before they can be
Reference to any commercial product or enr\ ice
is made with the understanding that no dicrnmi-
nation is intended and no endorsement by the
U.S. Department of Agriculture is implied.
USDA prohibit, discrmination in lii program,
on the basis of race, color, national origin. se'.
religion, age, disability political beliefs. and
marital or familial status tNot all prohibited
bases apply to all programs. Person-s with
disabilities who require alternative means for
communication of program information
SBraille. large print, audiotape. etc 1 should
contact USDA's TARGET Center at (2021 72?(
26)0 (olice and TDD). To file a complaint.
wnte the SecretarN of Agriculture. U.S.
Department of Agriculture. Washington. DC
20250. or call 800') 245-63410 koicel or 1202i
7210-1127 iTDDi. USDA is an equal opportu-
nity employer.

Agricultural Research

Mass-Reared Insects Get Fast-Food 4

Fire Blight Under Wraps 8

Cotton Drying System Saves Energy 11

Making the Most of Manure 12

Livestock Behavior Facility Opens 14

Cannabinoid Receptors Key to Stress Response 15

Foods To Be Fortified With Folic Acid 16

MAYSIN: a Natural Insecticide From Corn Silk 18

Mirl Gene Stalls Corn Pests 19

Chilly Research Thwarts Soil Erosion 20

DNA Fingerprinting of Rice Varieties 22

Geranium Virus Hard To Identify, Easy To Spread 22

Science Update 23

('oer: A green
lace% ing lar a
dines on uhitell.
nt mphs. Magniried
about 75\ on coser.
Pholo bi Jack
I)skinga. (K7545-9i

Agricultural Research/June 1997



"If we could give our predatory
insects a blindfold test, they wouldn't
be able to tell the difference between
their normal food and the artificial
diet we developed," says Allen C.
Cohen, an Agricultural Research
Service entomologist who recently
applied for a patent for his invention.
With this diet, scientists can now
mass-rear big-eyed bugs, Geocoris
punctipes, and lacewings,
Chrysoperla carnea. Both are
voracious insects that devour a
wide range of plant-destroying
insects. Their menus include the
sweetpotato and other whiteflies,
aphids, scale insects, moth eggs
and larvae, and mealybugs.
"The largest uses of this diet
and the predaceous insects it feeds
might be against the silverleaf
whitefly, also known as strain B
of the sweetpotato whitefly," says
ARS entomologist Thomas J.
Henneberry. He is director of the
agency's Western Cotton Re-
search Laboratory in Phoenix,
Arizona. "This insect is distribut-
ed worldwide and is a billion-
dollar pest of cotton and vegetables,
with more than 300 host plants."
"Crops in Arizona, California,
Texas, and Florida have been espe-
cially hard hit by the tiny, sap-
sucking insect since its discovery in
this country in 1986," Henneberry
says. "From 1991 to 1994, for
example, the whiteflies-Bemisia
argentifolii-have been blamed for
close to $1 billion in farm and related
economic losses in southern Califor-
nia's Imperial Valley."
Beneficial predators have been
used for decades for insect control.
However, their widespread use has
been hampered by inadequate

A specialized feeding mechanism of the
big-eyed bug, Geocoris punctipes, allows it
to squirt a digestive enzyme into prey and
then suck out their insides. Magnified
about 60x.
Agricultural Research/June 1997

methods to rear them on artificial
diets or by the cost of rearing prey for
them to feed on.
For example, a lacewing that is
mass-marketed requires a diet of
insect eggs that costs more than $300
per pound to produce. The new diet
can be made for about $2.50 per
pound. And each pound of the new
diet can produce about 30,000 big-

Using video microscopy, entomologist Allen Cohen
observes details of a green lacewing larva feeding on
a cabbage looper larva. This vigorous lacewing is a
14th-generation progeny reared on the new diet.

eyed bug adults or up to 10,000
lacewing adults that will yield about 3
million eggs during their lifespan.
One of the more interesting facts
revealed in the patent application is
that the diet consists of food ingre-
dients anyone can get at the
grocery-ground beef and beef liver.
Besides beef, the diet can be made
from fish innards, oysters, or meat
and liver from other animals-
whatever is cheapest.
"We expected the insects to go for
what we would call a junk-food diet
because they need cholesterol and
cannot manufacture it themselves,"
says Cohen. "Our new diet has
enough cholesterol to sink a battle-
ship, or to give the whole crew heart
disease. A key feature of this new line
of insect diets, since they are present-
ed in a solid or semisolid form, is that

we can pack them with the high
cholesterol and fat contents that are
relished by predatory insects."
But the key was getting the diet to
mimic the actual texture of natural
prey. That turned out to be another
item from the supermarket-eggs.
Cooked hens' eggs provide stickiness
to hold or retain the medium's com-
ponents and nutrients and help pre-
vent their separation. The egg
whites also provide extra proteins,
while the yolks are an excellent
source of cholesterol, lipids, lipo-
proteins, protein, and B-vitamins.
With slight modification, the
diet works for other beneficial
predatory arthropods.
The hallmark of this diet and its
reason for success are that it is
based on the predators' feeding
biology and nutritional chemis-
try-processes that were misun-
derstood for decades.
Before Cohen's studies, ento-
mologists and insect nutritionists
thought that the predators and
parasitic insects known as ento-
mophages drank only the body
fluids of their prey. Cohen's work
shows that these entomophages
actually absorb the concentrated solid
materials inside their prey. This
discovery led to the entirely new
approach to predator and parasite
Each diet parallels the composition
of nutrients in the biocontrol insect's
natural prey. The ARS scientists
determined this by dissecting the prey
by protein hydrolysis and subsequent
amino acid analysis, gas-liquid or
liquid chromatography of lipids,
microbial bioassay of vitamins,
atomic absorption spectrophotometry
for minerals, and overall bioassay.
The key to developing the new di-
ets was obtaining a thorough under-
standing about how these and most
other predatory arthropods actually
eat their natural prey. It seems they

digest their target prey outside their
bodies. This process, now gaining
wide recognition in the scientific com-
munity, is called extra-oral digestion.
For example, a big-eyed bug punc-
tures another insect with a sharp,
stingerlike structure that comes out of
its mouth. Then it squirts a digestive
enzyme that dissolves or breaks down
the prey's insides. The big-eyed bug
can then use the hollow stinger as a
straw to suck up its meal.
This is not unique among such in-
sects; about 80 percent of all predato-
ry insects and their relatives eat this
way, including spiders, mites, scorpi-
ons, and centipedes.
"This extra-oral-digestion feeding
mechanism allows lacewing larvae,

big-eyed bugs, and other predators to
feed on much larger insects than bio-
control users previously expected. All
they have to do is anchor themselves
and begin eating," says Cohen.
"And eat they do-up to 25 to 50
percent of their own body weight in
prey each day. They strongly prefer
to eat larger prey over smaller ones.
Expecting a lacewing larva or big-
eyed bug to sustain itself by eating
only the smallest whiteflies or aphids
exclusively is like expecting a 250-
pound football player to thrive on
sesame seeds eaten one at a time.
"Given a choice between large and
small prey, big-eyed bugs and most
other arthropods that use extra-oral
digestion eat the largest ones first,"

says Cohen. "This appears to be a
mechanism to get the large amount of
nourishment they need to survive. But
the observation is contrary to what
some entomologists had previously
thought," he says.
"Such feeding behavior could ex-
plain why some proven predators
didn't work out in fields. They may
have eaten the target insect in labora-
tory tests, but when released in actual
fields, they went after larger insects
and not the problem insect we'd tar-
geted for them.
"One of the surprises that came
from this research is seeing how effi-
ciently these predators can extract nu-
trients from their prey's body," Cohen
says. "At first, biocontrol experts un-

To be sure an artificial diet contains all the nutrients necessary for a beneficial predator to thrive, technician Donald
Brummett performs an amino acid analysis of its usual fare-cabbage looper eggs.

Agricultural Research/June 1997

Green lacewing larva attacks a cabbage
looper larva. Magnified about 15x.

derstood this efficiency as a disap-
pointment, because it meant that more
predators would be needed to kill the
numbers of insects that growers want-
ed to eliminate. These predators do
not engage in wasteful killing as was
once postulated.
"But when we have a realistic pic-
ture of the true nature of the preda-
tion, we can make adjustments by us-
ing more predators. We have a good
thing with them. In nature, they are
considered to be keystone species that
stabilize and regulate populations of
plant-eating insects. By understanding
their assets and liabilities and treating
them realistically and with respect for
their potential usefulness, we can get
them to do the same kind of work in
our agricultural fields as they do in
nature," says Cohen.
Insects that eat the diets produce
more offspring, often mature faster,
and are up to 1-1/2 times larger than
those feeding in the wild. The larger
size is not a sign of obesity or some
unhealthy phenomenon.
"These predators coming off the
diet are at fighting weight, ready to
consume several times their weight in
pest insects over a few days," says
Cohen. "Insects don't seem to get
obese the way mammals do."

Entomologists praise C. carnea
highly as a generalist predator. It sup-
presses aphids, lepidopterans (both
eggs and small larvae), and a variety
of other slow or nonmoving, soft-
bodied arthropods. It could make a
good candidate for mass-rearing and
release because it has good search
qualities and high kill rates and has
been proven not to attack other bene-
ficial arthropods or crop plants. It is
also one of the most voracious preda-
tors found in agricultural systems.
"It is a native species, as are several
related species used for biological
control," says Cohen. "This family of
insects is known to feed exclusively
on prey, so they can do no damage to
crop plants. Since C. carnea is well-
known and respected by growers, its
mass-production and distribution will
not take a great deal of selling."
C. carnea is already being sold
commercially to greenhouse growers
and those with small plots of high-
value cash crops, but it is too expen-
sive for mass-release on major crops.
Until Cohen's diet, no other artificial
diet had proven cheap enough for
mass-rearing these insects.
Cohen's diet yielded C. carnea with
unexpected superior quality, compared
to insects reared on previously known
artificial diets or on its natural food
source, Sitotroga eggs.
Cohen has so far reared 16 succes-
sive generations of C. carnea, 130 of
G. punctipes, 3 of Serangium parcese-
tosum (a lady beetle), and 3 of Orius
insidiosus (a minute pirate bug).
In contrast to previous teachings,
Cohen discovered that he can include
antimicrobial agents like potassium
sorbate or streptomycin in the diet
without harm to the insects being
mass-reared. This prevents spoilage by
bacteria and fungi and extends the
shelf life of the artificial diet from
about 1-1/2 days to 3 to 4. When in-
sects are reared on these extended-life
products, workers have to change the

Technician Lisa Smith combines basic
ingredients such as ground beef and eggs
with antimicrobial agents and other
additives that enhance the quality and
shelf life of the insect-rearing diet.

packages less frequently, and that can
cut labor costs by about one-half.
"Large pet food processors might
help us get the diet into production,"
says Cohen. "They already have the
equipment needed to mass-produce the
feed. They could easily add the insect
diet product to their production line."
Cohen reports some interest on the
pet food sector's part and considerable
interest from the growing biological
control product industry. Evidence of
widespread interest is the financial
support that was provided by the Impe-
rial County Whitefly Committee for
development of the new insect diet.
The patent application (No. 08/
699,815) is titled "Artificial Media for
Rearing Entomophages."-By Dennis
Senft, ARS.
Thomas J. Henneberry is at the
USDA-ARS Western Cotton Research
Laboratory, 4135 E. Broadway Rd.,
Phoenix, AZ 85040; phone (602) 379-
3524, fax (602) 379-4509, e-mail
Beginning July 1, Allen C. Cohen
will be in the USDA-ARS Biocontrol
and Mass-Rearing Research Unit, P.O.
Box 5367, Mississippi State, MI
39762; phone (601) 323-2230, fax
(601) 323-0915. *

Agricultural Research/June 1997

Fire Blight Under Wraps

century since Louis Pasteur
proved that bacteria can cause
disease in animals.
A few years after that well-
known French scientist published his
work, an American professor, T.J.
Burrill of Illinois, began working
with an unknown disease that was
devastating apple and pear orchards
in the Midwest. In 1880, he discov-
ered that the disease now known as
fire blight was also associated with a
bacterium. And by 1885, Joseph
Arthur performed the experiment at
Cornell University that proved the
suspect bacterium was truly responsi-
ble for the disease, earning him the
first Doctor of Science degree
granted in America.
Like Pasteur, Burrill and Arthur
faced scorn and derision from distin-
guished scientists of their day.
Eventually, a U.S. Department of
Agriculture scientist named Erwin F.
Smith and colleagues overcame the
opposition and carried on additional
research in the early 1900s that
proved that bacteria cause diseases in
many plants. The fire blight bacter-
ium, Erwinia amylovora, was later
named for him.
Today, yet another USDA scientist
is investigating uncharted territory of
this bacterial disease. Plant patholo-
gist Tom van der Zwet has been
working with fire blight at Beltsville,
Maryland, and Kearneysville, West
Virginia, for 30 years.
"Fire blight attacks young fruit
trees-especially pear and apple-
causing leaves and fruit to shrivel and
blacken, as though scorched by fire,"
says van der Zwet. "Once it strikes,
there isn't much that growers can do.
[See also "Scientists Seek Limits on
Pear Pests," Agricultural Research,
November 1993, pp. 4-9.]
"Despite all the research that'd
been done on fire blight, we still
didn't know until recently if the bac-

This Rome Beauty apple tree inside an arborsphere at the Appalachian Fruit Research
Station in Kearneysville, West Virginia, has been pruned to remove all fire blight cankers.

Agricultural Research/June 1997


n ~I~
k 4
I. '`

terium resides in the large scaffold
limbs of an infected tree's vascular
system, or if it actually reinfects the
tree each season," he says.
To find out, last year van der Zwet
and soil scientist D. Michael Glenn,
entomologist Mark Brown, and tech-
nician Craig Cavin set up an aseptic,
whole-tree arborsphere-a kind of
plastic growth chamber-experiment
at the ARS Appalachian Fruit Re-
search Station in Kearneysville.
"From this research, we discov-
ered that the bacterium that causes
fire blight doesn't live in a tree's
older vascular system in numbers
sufficient to cause disease," van der
Zwet reports.
For the 6-month experiment, they
used four severely blighted, 12-year-
old Rome Beauty apple trees that had
suffered severe fire blight nearly
every year for the past 10.
In the fall of 1995, they heavily
pruned the trees and removed any
cankers or damaged bark that might
house bacteria. Then in March 1996,
they covered the trees with dormant
insecticidal oil to kill any insect eggs.
That treatment ensured no insects
would hatch that could wound the
trees' succulent new growth. Two
weeks later, two of the trees were
carefully hand-painted with
TennCop, a copper compound, to
eliminate any surface bacteria.
On April 25, 1996, van der Zwet
and colleagues covered two of the
trees-one copper-treated and one
not-with 14- by 14-foot, clear
plastic-and-pipe frames 16 feet high,

creating two arborspheres. They
equipped them with air supply
systems and bacterial filters. This
confinement was necessary because
the bacteria could be carried by
insects, rain, wind, or perhaps even
orchard tools, to attack new growth in
the spring.
On June 20th, the scientists first
checked for the fire blight bacteria by
lowering four open petri dishes con-
taining a selective growth medium
and sticky traps into the arborspheres.
They left them there for
4 days.
"Then, twice in early
July, we placed similar
dishes for 2 hours on the
outflow boxes where air
exited the arborspheres,"
van der Zwet explains.
"On July 23, we collect-
ed 10 shoots, free of
disease symptoms, from
several locations on the
control trees that weren't
under the arborspheres."
To check for the pres-
ence of fire blight bacte-
ria, the plates from the
arborspheres and the
control shoots were incu-
bated in the lab at 800F.
There was no sign of bacteria on
the samples taken from the arbor-
spheres, and sticky traps caught only
a couple of white apple leafhoppers.
Neither was there any evidence of
fire blight from a colony of adult
potato leafhoppers released into one
of the arborspheres. But the control

They equipped

them with air

supply systems

and bacterial

filters. This con-

finement was


Fire blight infects terminal
leaves on an unpruned and
uncovered apple tree.

necessary because

the bacteria could

be carried by in-

sects, rain, wind,

or perhaps even

orchard tools.

Agricultural Research/June 1997

Small Cause, Big Effect
Although microscopic-25,000 laid side by side or 12,000 laid end to
end would not measure more than an inch-fire blight bacteria can cause
big problems. One reason is that each bacterial cell is completely inde-
pendent. So, under favorable conditions, cells multiply by dividing at a
phenomenal rate, reaching 10 billion in 72 hours.


Plant pathologist Tom Van Der Zwet (center) and technicians John Walter (left) and Larry Crim examine trees outside of the
arborspheres for fire blight.

trees, not protected by the sterile
atmosphere of the arborspheres, were
heavily infected with fire blight.
"The unprotected trees began to
show the first signs of blight on June
4, about 3 weeks after new growth
emerged from the severe pruning we
had done in the previous fall, but no
fire blight symptoms ever appeared
on the trees in the arborspheres," says
van der Zwet.
The day after hurricane Fran de-
stroyed the arborspheres on Septem-
ber 16, 1996, 20 shoots were collect-
ed from the protected trees and close-
ly examined and plated in the lab for
the bacteria-none were found.
"For the first time, we've shown
that E. amylovora is not present as a
systemic pathogen in large scaffold
limbs of trees known to have been
infected for the previous 10 years,"
says van der Zwet.

Results from the arborsphere
experiment can help growers,
according to van der Zwet. Extreme-
ly heavy pruning results in an
overabundance of new, tender shoots
that are more susceptible to fire
blight infection. Therefore, when
trees are dormant, growers should
remove only the blighted shoots and
large cankers caused by bacteria.
However, proper pruning should also
ensure that there is adequate light
penetration into the tree canopy to
maintain good tree growth.
"Our next step is to look at the
presence of bacteria in younger shoot
tissues, internally and externally, and
to study the role of cankers in
primary infection of the fire blight
syndrome," van der Zwet says.-By
Doris Stanley, ARS.
Tom van der Zwet can be reached
at the USDA-ARS Appalachian Fruit

Research Laboratory, 45 Wiltshire
Rd., Kearneysville, WV 25430;
phone (304)725-3451, fax (304) 728-
2340. *

Fire Blight Bulletin
Available from the U.S. Govern-
ment Printing Office, Fire Blight-Its
Nature, Prevention, and Control: A
Practical Guide to Integrated Dis-
ease Management (Agriculture
Information Bulletin 631), published
in 1995 by the U.S. Department of
Agriculture, Agricultural Research
Service; GPO Stock No. 001-000-
04617-9; price $7.00 in United
States, $8.75 foreign. To order from
Superintendent of Documents, phone
(202) 512-1800, fax (202) 512-2250.
On the World Wide Web, go to http:/

Agricultural Research/June 1997


L en Alphin, co-owner of Com-
monwealth Gin of Windsor,
Virginia, says his new ARS-
designed conveyor-belt dryer handled
cotton so sopping wet it was impossi-
ble to dry in the conventional tower
dryer at another gin he owns. Tower
dryers use hot air to blow cotton pneu-
matically through a series of racks.
Weldon Laird, an ARS agricultural
engineer at Lubbock, Texas, designed
the belt dryer, along with colleague
Roy V. Baker and others. He says,
"The belt dryer had no trouble drying
the cotton because the belt moves
slowly enough to let the cotton stay in
the heated air for up to 90 seconds or
longer-instead of the 6 to 12 it has
when blowing through a conventional
tower dryer at high air pressure.
"This machine not only takes the
time needed to do the job, but it saves
money and often does a better job of
preserving cotton fiber quality," says
Laird. "The temperature is about half,
the horsepower's a fraction that of a
tower dryer's, and the air pressure is
100 times lower-adding up to energy
savings. It pays for itself in 1 to 5
years, depending on a gin's yearly
production," he says.

Laird's dryer carries cotton piled in
an even layer on a wire mesh belt that
is 6 feet wide by 40 to 70 feet long.
Hot air is forced downward through
the cotton and the belt.
Currently, two gins in Texas use
the belt, as well as the Virginia gin.
"One Texas gin has dried 354,000
bales of cotton with the belt over the
past 5 years," says Laird. "The Terry
County Co-op Gin of Brownfield,
Texas, found that when they first got
the dryer it conditioned very wet cot-
ton so well that only 11 percent was
classed below grade, compared to
100% of a similar batch that was dried
before the belt dryer was installed."
Managers of a kenaf-processing
plant in Mississippi also turned to
Laird and his belt dryer for help when
they faced a backlog of 3 crop years
worth of kenaf to dry. Kenaf is a
bamboo-like relative of cotton used to
make a variety of products, including
textiles and paper.
From 1985 to 1990, Laird worked
on building and testing a prototype
dryer and operating system at the
Lubbock lab. Then the Chickasha
Cotton Oil Company of Casa Grande,
Arizona, joined about a dozen state
and national cotton organizations in a

cooperative field demonstration to
determine the system's efficacy.
Laird is now working on a new
application with Cotton Incorporated
of Raleigh, North Carolina: to dry
cottonseed coated with a wet corn-
starch solution to create a flowable
product for cattle feed. The Chickasha
Company plans to test it in one of
their plants in Georgia.
ARS research has shown cotton-
seed to be a nutritious cattle feed. But
cottonseed has failed to move into
widespread use because it has sticky
fibers that cause it to clump together
and jam feed-processing equipment.
By coating the seeds and then using
the conveyer belt to dry the coating,
Laird and his colleagues produce seed
as hard as corn or other grain feeds.
"Unlike for cottonseed oil, where
there's a glut, there's a big market for
cottonseed feed that we can open up if
this works," says Laird.-By Don
Comis, ARS.
J. Weldon Laird and Roy V. Baker
are at the USDA-ARS Cropping
Systems Research Laboratory, Box
215, Lubbock, TX 79401; phone (806)
746-5353, fax (806) 744-4402, e-mail *

Agricultural Research/June 1997


Cotton Drying System

Saves Energy



To preserve the nitrogen content of manure for fertilizer, Agricultural Research Service dairy scientists are helping farmers to choose the
right feeds for cows and are developing tests to analyze for manure nutrients.

any urban dairy farmers see
livestock manure as a prob-
lem, especially when it comes
to getting along with their neighbors.
But manure can also be a source of
nutrients for feed crops and a valuable
fertilizer for suburban gardeners, too.
Animal, crop, and soil scientists at
USDA's Beltsville (Maryland)
Agricultural Research Center have
joined forces to search for ways to
recycle nutrients in dairy manure.
Four Agricultural Research Service
research labs, one in ARS' Livestock
and Poultry Sciences Institute (LPSI)
and three in its Natural Resources
Institute (NRI), are involved.
"The key to this research is keep-
ing nitrogen and other nutrients in a
cycle found on every dairy farm,"
says project leader Robert J. Wright,
who is with the NRI's Environmental
Chemistry Laboratory. "It's a matter
of capturing and storing the nutrients
in dairy manure and then applying
them to the soil to nourish crops,
which, in turn, feed the livestock. All
the while, we're focusing on keeping

farms profitable, protecting soil and
water quality, and preventing odors."
"Actually, profits and environmen-
tally sound management can go hand
in hand," says ARS dairy scientist
Barbara P. Glenn. She heads the
LPSI's Nutrient Conservation and
Metabolism Laboratory.
"Dairy producers are paid based on
the protein in cows' milk. So, if more
of the nitrogen in feeds ends up as
milk protein, it's good for business,"
says Glenn.
This kind of cooperative research is
going to be more vital in the future.
Bedroom communities near dairy
farms are increasingly concerned
about environmental impacts. In fact,
right-to-farm laws, which protect
responsible farmers from frivolous
lawsuits from nonfarming neighbors,
have popped up nationwide. Giving
farmers simple methods to reduce
odors can improve their relationship
with area residents and possibly head
off legal conflicts.
Diet might be one area where
farmers could make subtle changes
with big results.

Normally, only 25 percent of the
nitrogen fed to an animal is recovered
as milk protein. The rest is excreted,
with as much as half escaping into
the air as ammonia gas and other
odorous compounds. Less than 35
percent of the nitrogen is left to
recycle as a nutrient for crops. A
change in feeds might reduce the
nitrogen waste and add to the nutri-
tional value of a cow's milk.
Glenn's group is exploring how
the cows' diet can be formulated to
improve nitrogen efficiency. Chemist
James B. Reeves is working to
develop rapid on-farm tests to gauge
the nutrients in livestock manure so
farmers will know its fertilizing
potential. Other researchers are trying
to identify compounds to absorb
nitrogen from manure on the barn
floor, to enhance the value of manure
fertilizer and reduce odors.
The loss of nitrogen as ammonia
occurs in the barn, during storage,
and after land application. But
ammonia is only a part of the odor
problem; a host of compounds
contribute, and some are not even

Agricultural Research/June 1997

identified yet. Biomedical engineer
Alan M. Lefcourt will measure the
amount and types of gases lost, both
from dairy cows and their manure.
An important part of this research
project is its interconnectivity. Each
researcher's work complements that
of others. For example, if Glenn's
group can help farmers choose the
right feeds and develop tests to
analyze for manure nutrients, produc-
ers will still need effective ways to
apply the manure.
Soil scientists Rodney Thompson
and Jack Meisinger, who are with the
NRI's Environmental Chemistry lab,
have been looking at that aspect.
"Farmers usually broadcast ma-
nure on the soil surface because it's
the quickest and cheapest way of get-
ting it on the land," says Thompson.
"Unfortunately, that opens the door
for potentially valuable nitrogen to
evaporate as odor-causing ammonia."
But if farmers plow under the ma-
nure-effectively mixing it with the
soil-they can prevent this loss, the
scientists say. They plan to compare
nitrogen losses in plowed and spread
fields to demonstrate that this tech-
nique is worth the extra effort.
"Having the manure on the surface
creates an ideal situation for gas
exchange, and that's what ammonia
evaporation really is," Meisinger
says. "You lose almost half of the
available nitrogen because the
manure is sitting on the surface. But
soils absorb ammonia very nicely if
you just get that soil contact."
Another way farmers could
someday profit from their herds'
manure is by selling it to suburban
homeowners as a composted product.
This is the research goal of
Lawrence J. Sikora, who is with
NRI's Soil-Microbial Systems
Laboratory. Sikora's expertise lies in
finding effective new ways to make
crop-fertilizing compost out of waste
products. Sikora is exploring how

Manure collection tank at the Beltsville
(Maryland) Agricultural Research Center.

municipal waste could be combined
with manure, a process known as co-
composting, to make an effective
Sikora says that cities could
remove the glass, plastic, and metal
from their trash for recycling because
they offer no benefits to plants.
What's left is a high-carbon mix such
as paper products and leftover
food-all of which are good for
composting. It's just that the result-
ing compost has a problem.
"With so much carbon-based
material, this compost is very defi-
cient in nitrogen," says Sikora.

Using a small wind tunnel system, soil
scientist Rodney Thompson prepares to
measure ammonia loss from liquid dairy
manure applied to the soil surface.

"Seedlings would come up yellow if
you put this compost on the soil.
That's because microorganisms in the
compost material are actually taking
the soil's nitrogen from the plants."
Making an urban-dairy manure
compost could solve lots of prob-
lems, but it also presents challenges.
Though composting is not odor-free,
these odors are manageable. And to
make the effort of composting
worthwhile, the product created has
to have market value. Sikora's
colleague, microbiologist Patricia D.
Millner, is looking at co-composting
from these practical angles.
But any solutions found during
this research must also keep farms
profitable. That's why the team also
includes economist Yao Chi Lu. Lu
will be reviewing all the research to
ensure that any whole-farm system
designed by researchers allows the
farmer to make money, protects the
environment and keeps the farm in
the family for generations to come.
"Right now a lot of this research is
just getting started," says Lu. "So I'm
preparing myself by becoming
acquainted with everything about
dairy operations and how they make
profits. That way I can design
computer models that will tell us
whether these ideas will allow farms
to prosper-not only a year from
now, but 30 years later."-By Jill
Lee, ARS.
Barbara P. Glenn is at the USDA-
ARS Nutrient Conservation and
Metabolism Laboratory, Bldg. 200,
10300 Baltimore Ave., Beltsville, MD
20705-2350; phone (301) 504-8315,
fax (301) 504-8162, e-mail
Robert J. Wright is at the USDA-
ARS Environmental Chemistry
Laboratory, Bldg. 007, 10300
Baltimore Ave, Beltsville, MD 20705-
2350; phone (301) 504-5443, fax
(301) 504-5048, e-mail *

Agricultural Research/June 1997

Livestock Behavior Facility Opens
New laboratory aids study of animals' response to environment and stresses.

I t's a high-tech laboratory for sci-
entific research, though it looks
like an ordinary livestock build-
ing. The newest research facility for
the ARS Livestock Behavior Research
Unit is built for cattle and hogs-and
the scientists who study them.
"It's a real laboratory, not just a
building," says Julie Morrow-Tesch,
an animal physiologist/ SCOTT BAUEF
ethologist who heads the
unit. But the 10,000-square-
foot structure built in 1996
and opened in early 1997
was designed for scientific
research on a practical level.
"Our program has three
specific objectives," says
Morrow-Tesch. "These are
to identify how animals
perceive and interact with
their environment, deter-
mine if sensory cues in their *
environments change
animals' behavior and ..
response to stress, and "'
identify their preferences for
environments or items in
their environment that may
affect their behavior and
response to stress."
The size and flexibility of
the new building were
dictated in large part by the
type of research that was to
be conducted in it.
"We wanted a building
large enough to conduct a
wide range of studies. Now,
we can quickly create any
size pen or housing system Technicia
inside it," she says. physiology
One important tool the instantan
building will house is a identify v
Heb-Williams maze. This is
actually a series of 12 mazes--each
more difficult than the previous one-
made up of gates, alleyways, and
other barriers.
"Livestock spend a majority of
their time looking for food, which

requires spatial orientation," says
Morrow-Tesch. "The maze allows us
to identify and quantify their learning
cues to determine what is important
to them in their environments."
Historically, livestock researchers
have worked in production pens and
facilities. Those settings presented
challenges for scientists who wanted

n Jeff Dailey places a calf into a T-maze while ani
ist Julie Morrow-Tesch begins collecting both
eous data and video records. The maze is used to
various preferences of young dairy calves.

to isolate individual animals or
conduct laboratory-quality experi-
ments. But the sheer size and weight
of cattle and hogs made it impractical
and often costly to design and build
custom experimental pens.

The new building will enable
researchers to conduct experiments in
a highly controlled environment that
is comfortable for both the animals
and themselves. And the installation
of post holes in the floor every 8 feet
in all directions lets scientists build
custom-sized pens and mazes using
standard, commercially available
livestock panels.
This will save money in
the future, says Morrow-
Tesch, because the scientists
won't have to special-order
materials or contract out for
custom-size panels to
complete their work. "We
are committed to getting the
most for the taxpayer's
dollar with this project."
Designed to be slip-
proof, the floor has narrow,
3/4-inch-deep grooves every
1-3/4 inches, so cattle and
hogs won't lose their
footing. "This was based on
scientific research and to
accommodate dairy cattle,
which have a larger, cloven
hoof and need a slip-proof
surface to keep their bal-
ance," says Morrow-Tesch.
The laboratory also
features a traditional
physiology laboratory
where scientists can prepare
samples, such as blood
plasma, without having to
transport them off site. A
built-in electronics shop
allows researchers to build
and maintain their own
"We do a lot of things
that require us to assemble
equipment for experiments. We can
save money by doing this ourselves,
rather than contracting out for special
projects," says Morrow-Tesch.
"Our work is not in the traditional
line of animal science research," she

Agricultural Research/June 1997

says. "Livestock behavior has never
been examined in depth. Many
current livestock production practices
are based on tradition, or on trial and
error. Our goal is to find scientific
bases for behaviors and then use that
information to determine what
practices are best for both livestock
and producers."
For example, animal physiologist
Gary Weesner has discovered a
chemical pathway in pigs and cloned
the DNA for the chemical receptor in
the pig's brain. He is currently
researching the effect of the chemical
on pigs' ability to cope with stress.
[See "Cannabinoid Receptors Key to
Stress Response," next column.]
Scientists in the unit have also
studied typical livestock behaviors,
such as buller-steer syndrome. This is
an aggressive behavior observed in
feedlot cattle in which one individual
steer is singled out and bullied by the
others. It leads to illness, injury, and
even death for the bullied steer and
annually costs producers thousands of
dollars in lost productivity.
Other research will examine the
impact of common livestock manage-
ment practices such as castration and
tail docking, as well as feeding
behavior in pigs.
"Our work with castration tech-
niques in cattle shows no discernible
difference between castrating newly
weaned bulls-either by banding or
surgery-and performing the proce-
dure 3 weeks before weaning," says
Morrow-Tesch. "This is important
because castration affects feed intake,
weight gain, and animal health."-By
Dawn Lyons-Johnson, ARS.
Julie Morrow-Tesch is in the
USDA-ARS Livestock Behavior
Research Unit, Purdue University,
Department ofAnimal Science, 1026
Poultry Science Bldg., West Lafay-
ette, IN 47907-1026; phone (765)
494-8022, fax (765) 496-1993, e-mail *

Cannabinoid Receptors Key

to Stress Response

Livestock producers lose more
animals or see feed efficiency or
market weight decline when animals
are under stress.
Now it appears that stress causes
some livestock-cattle and hogs in
this study-to produce calming brain
compounds called cannabinoids.
Scientists at an Agricultural
Research Service lab in West Lafay-
ette, Indiana, are conducting studies
to measure how these compounds
influence livestock behavior.
They say mixing pigs into new
social groups and other common on-
farm practices actually activate the
cannabinoid pathway in pigs. This
shows the animal can turn the
cannabinoid system on and off
during stressful situations.
Gary Weesner, an animal physiol-
ogist with the lab, has studied the
cannabinoid pathway in pigs and
cloned DNA associated with cannab-
inoid receptors, enabling researchers
to track the activity of the chemical.
"We can't measure the cannab-
inoids in the animal itself," Weesner
says, "but we can detect the recep-
tors. At present, they're the only part
of the cannabinoid pathway that we
can check. We do not yet have the
ability to measure natural levels of
"Cannabinoid receptors function
like doors on cells that open to let in
certain compounds that activate the
cells," says Weesner. "These recep-
tors are on cells only in certain areas
of the brain-including those associ-
ated with pain and pleasure."
To study how cannabinoids affect
animals under stress, Weesner
compared the level of cannabinoid
receptors found in the brains of two
separate groups of pigs. He selected
10 boars-uncastrated male pigs-
and subjected one group of 5 to a
series of stresses typical in farm
settings. These pigs were run through
a series of gates and pens, in a

simulated shipping exercise, and then
mixed with other boars.
"We selected boars because they
are aggressive by nature," Weesner
says. At the conclusion of the experi-
ment, the level of cannabinoid recep-
tors in the pigs' brains was analyzed.
The second group of pigs was not
moved or mixed with other pigs.
Scientists found a significant
increase in the number of cannabi-
noid receptors in the group of pigs
subjected to the moving and
regrouping exercise compared to the
control group.
"We confirmed the cannabinoid
pathway is being activated," Weesner
says. "If animals remained stressed
for longer than 30 minutes we
noticed the numbers of cannabinoid
receptors remained higher."
Weesner explains the next step is
to determine how cannabinoids affect
the immune system in animals and to
determine if the activation of the can-
nabinoid pathway has a positive or
negative impact on animal health.
Scientists may be able to use that
information to help producers refine
livestock management practices.-
By Dawn Lyons-Johnson, ARS.
Gary D. Weesner is in the USDA-
ARS Livestock Behavior Research
Unit, Purdue University, 1026
Poultry Science Bldg., West Lafay-
ette, IN 47907-1026; phone (765)
494-6938, fax (765) 496-1993, e-mail +

Agricultural Research/June 1997

Foods To Be Fortified With Folic Acid

Elderly may benefit most.

Beginning in January 1998,
the B vitamin folic acid will
be added to enriched bread,
flour, cornmeal, rice, pasta, and other
grain products, according to a 1996
U.S. Food and Drug Administration
(FDA) regulation.
The regulation grew out of evi-
dence that the risk of spina bifida and
other neural tube defects in newborn
infants dropped if mothers took more
folic acid before pregnancy.
In 1992, the Public Health Service
recommended that all women of
childbearing age consume 400 micro-
grams (mcg) of folic acid daily to re-
duce risk. That 400 millionths of a
gram could spare many of the 2,500
infants born in the United States with
neural tube defects each year.
But the defects occur so early in
pregnancy-within the first month-
that the damage might be done before
an expectant mother began taking
supplements. So fortifying the food
supply was the most efficient way to
reach most women of childbearing
age. According to FDA estimates, the
benefits of reducing neural tube de-
fects outweigh the costs of fortifica-
tion by at least 24 to 1.
The potential savings from reduc-
ing cardiovascular disease and stroke
may be far greater, says Katherine L.
Tucker of the Jean Mayer USDA Hu-
man Nutrition Research Center on
Aging at Tufts University in Boston,
Tucker collaborated with Jacob
Selhub, Paul Jacques, and Brenda
Mahnken at the USDA center and
Peter W. F. Wilson, who is with the
Framingham Heart Study, to produce
the latest evidence that an adequate
folate intake could reduce the risk of
these diseases.
Folate-which includes folic acid
and its several food forms-is one of
three B vitamins the body needs to
convert the amino acid homocysteine
to an innocuous relative. It appears

that an excess of homocysteine circu-
lating in the blood adds to the damage
that restricts blood flow to the heart
muscle and the brain, thereby increas-
ing risk of a heart attack or stroke.
In fact, says Tucker, other re-
searchers estimate that high homocys-
teine increases the odds for coronary
artery disease by 60 percent in men

Some foods that will be fortified with folic
acid in 1998.

and by 80 percent in women, based on
studies prior to 1995. And the odds
for cerebrovascular disease increases
by 50 percent in both genders by
these estimates.
A epidemiologist, Tucker and col-
leagues estimate that the risk of coro-
nary artery disease may drop by 3 to 5
percent when grain products are forti-
fied at the regulated level.
The researchers analyzed data on
the eating habits of 855 elderly men
and women, along with their blood
folate and homocysteine levels. The
subjects, ranging in age from 67 to
96, were all participants in the
Framingham Heart Study that began

in the 1950s. As part of the study, they
periodically fill out extensive ques-
tionnaires on their dietary habits and
use of supplements and provide blood
samples. Selhub had earlier analyzed
the samples for homocysteine, folate,
and two other B vitamins involved in
converting the amino acid to a less
toxic relative.
In addition to projecting the effects
of fortification, the researchers exam-
ined the major folate sources reported
by the participants.
"What surprised us was the remark-
ably strong inverse relationship be-
tween blood homocysteine levels and
intake of cold breakfast cereals and of
total fruits and vegetables," she says.
"Each food group showed a very clear
dose-response relationship."
And that's after adjusting the data
for age, gender, total calorie intake,
and use of dietary supplements con-
taining folate.
Study participants who reported eat-
ing at least five to six servings of fruits
and vegetables daily or one serving of
breakfast cereal had the highest blood
folate levels and the lowest homocys-
teine levels.
Orange juice and dark-green leafy
vegetables, such as broccoli and
spinach, contributed the most folate
among the fruits and vegetables, notes
Tucker. Dried beans and peas and
most berries are also good sources.
The highest homocysteine levels
were found in those who ate less than
three servings of fruits and vegetables
daily and seldom ate cereal.
Supplement users had the lowest
homocysteine levels, but not much
lower than frequent consumers of
fruits, vegetables, and cereals.
"This suggests that people can sub-
stantially reduce their health risk sim-
ply by changing their diet," she says.
"That's especially important for the
elderly, who tend to have low folate
status." She suspects the findings will
be true for younger people and plans to

Agricultural Research/June 1997

7 Percent of elderly estimated to
ingest the recommended 400
mcg of folic acid daily.
SPerceni of elderly with high 7( 5
homocysleine levels





SI. I6.21

Unfortified 140 280 350 700
Micrograms (mcg) of folic acid fortification per 100 grams of flour
* Based on a study of 855 elderly participants in the Framingham Heart Study

look at eating patterns of the offspring
of Framingham study participants.
In setting the fortification regula-
tion, FDA adopted the conservative
level of 0.43 to 1.4 milligrams of folic
acid per pound of product. In scientif-
ic measure, "that's about 140 micro-
grams of folic acid per 100 grams of
flour," says FDA food chemist Jeanne
Rader. "The amount varies in other
products, such as rice and pasta, to
compensate for differences in how
they are prepared."
Using the dietary data, Tucker and
colleagues estimated how the current-
ly mandated level and three higher
levels proposed during the decision-
making process would affect the eld-
erly's total folate intake and blood ho-
mocysteine. At the mandated level, a
little more than half the elderly popu-
lation would get the desired 400 mcg
of folate daily, compared to a third
without fortification. And the percent-
age of elderly with high homocysteine
would drop from 26 to 21.
That percentage would continue to
drop at increasingly higher levels of

1 2.4

fortification (see graph). So why not
add more folic acid to selected foods?
In addition to the added cost,
"there's the concern that fortification
will add to the already high intake
among supplement users and thus
cover up a deficiency of vitamin
B12," says Tucker.
Deficiencies of either folate or B12
cause a type of anemia (macrocytic)
that can be corrected by taking folic
acid. So adding extra folate to the
diet could mask a B12 deficiency, be-
cause the standard diagnosis for B12
deficiency tests for anemia.
"It's like covering up a red flag,"
Tucker explains.
Moreover, some suggest that extra
folate can actually trigger nerve dys-
function due to B12 deficiency, caus-
ing symptoms such as diminished
sense of balance or sound perception.
"It's a problem that needs a lot more
attention, with or without fortifica-
tion," she notes.
One in five people over age 60 and
two in five people over 80 don't se-

create enough stomach acid to absorb
vitamin B12 in their food, according
to other research at the center. So
they can be deficient even if dietary
intake is adequate. And many cases
of deficiency go undetected because
many deficient people aren't anemic.
"We need a better diagnostic ap-
proach," says Tucker.
Until that happens, the question of
folate fortification is a balancing act
between adding enough to reduce
disease risk without masking vitamin
deficiency. To that end, Tucker esti-
mated how much the different levels
of folate fortification might increase
the risk of imbalance. Using a daily
folate intake of 1,000 mcg as the
threshold, the risk stayed well below
1 percent of the elderly population at
the mandated level and at 280 and
350 mcg per 100 grams of flour.
Imbalances are most likely to oc-
cur in people who take supplements,
because few would get enough folate
through diet alone.
The elderly can reduce this risk by
making sure their supplement con-
tains substantially more B12 than the
current Recommended Dietary Al-
lowance, says Tucker. People who
can't absorb the vitamin from foods
because of low stomach acid can ab-
sorb some of the crystalline form in
vitamin supplements.
"The balance of evidence from this
study suggests that the benefits of
folate fortification at the currently
mandated level would greatly out-
weigh the risks," she concludes, add-
ing that a better diagnosis for B12 de-
ficiency should be given high priori-
ty.-By Judy McBride, ARS.
Katherine L. Tucker is at the Jean
Mayer USDA-ARS Human Nutrition
Research Center on Aging at Tufts
University, 711 Washington St., Bos-
ton, MA 02111; phone (617) 556-
3351, fax (617) 556-3344, e-mail
tucker@hnrc. tufts. ed *

Agricultural Research/June 1997


A natural insecticide in tt
succeed in transferring g

T he worm that turns the sweet

corn ear into mush may be
in for a turn of events,
thanks to a plan as smooth as silk-
corn silk, that is.
Agricultural Research Service
scientists at Columbia, Missouri, and
Tifton, Georgia, plan to manipulate a
genetic pathway in corn silks to boost
the production of maysin, a com-
pound that gives the plant natural
insect resistance.
"If it works, it will mean a sweet
success for consumers and growers,"
says Michael McMullen, an ARS
plant geneticist. "An added benefit of
controlling the corn earworm would
be in keeping it from moving on and
damaging other crops like alfalfa,
cotton, peanuts, and tomatoes."
Earworms cost U.S. growers more
than $100 million annually. Increas-
ing maysin concentrations in corn
silks could reduce insecticide used on
sweet corn by up to 85 percent. Com-
mercial growers sometimes have to
apply insecticides 30 times a season
to keep earworms out of sweet corn.
Adult earworms lay their eggs
directly on the silk of growing corn,

ie silk of some corn lines will deter earworms in the future if ARS scientists
enes that control the production of maysin.

where the larvae hatch about 3 days
later. The newly hatched larvae eat
their way through the silk, then feed
on kernels, before dropping to the
soil to mature.
After 12 days, new adults emerge
from the soil and fly away in search
of fresh food. It's then that they
move into all sorts of other crops,
including many home gardens.
The research plan, as designed by
McMullen and plant geneticist
Patrick Byrne, is to locate and
characterize the genes that regulate
the maysin-producing pathway.
McMullen and Byrne are working
with plant geneticist Neil Widstrom,
entomologist Billy Wiseman, and
University of Georgia chemist
Maurice Snook.
They have already identified a
gene named PI that regulates more
than half the amount of maysin in
one corn population. If they can
increase the expression of PI in corn
silks and identify and manipulate
other pathway genes, they then can
increase the amount of maysin.
"Maysin, which occurs mainly in
corn silk, binds up amino acids in the

earworm's gut so the insect can't use
them and literally starves to death,"
says Byrne.
Once the Missouri group has
identified the key maysin genes,
Widstrom will cross and select corn
plants in Georgia that have the
desired genetic makeup.
Maysin was first identified as a
compound conferring resistance by
the Tifton scientists in 1979. But only
recently have gene mapping tech-
niques become advanced enough that
the likelihood of built-in resistance to
earworms is just a few years away.
The Tifton researchers found
maysin in a primitive race of corn
from Mexico, highlighting the value
of maintaining a large collection of
exotic stocks in USDA's National
Plant Germplasm System.-By
Linda Cooke, ARS.
Michael D. McMullen and Patrick
Byrne are in the USDA-ARS Plant
Genetics Research Unit, University
of Missouri, 204 Curtis Hall, Colum-
bia, MO 65211; phone (573) 882-
7606, fax (573) 884-7850, e-mail
mcmullen@ *

Agricultural Research/June 1997

Mirl Gene Stalls Corn Pests

T o pupate from caterpillars
into adult moths, fall army-
worms and southwestern
corn borers must go on a 10- to 20-
day feeding binge. Their fare is the
stalks, leaves, husks, and ears of corn
plants. Unchecked, they can cause
losses of 30-plus percent.
But now scientists may have a way
to turn the tables on the pests: geneti-
cally engineer the plants so they chur
out a rare natural enzyme that curbs
the caterpillars' destructive appetite-
so much so, they'd grow to less than
half their normal size and weight.
"The idea is to reduce their ability
to chew up the plant and to slow their
reproduction," explains Dawn S.
Luthe, a Mississippi State University
(MSU) molecular plant biologist.
Except for so-called tropical corn,
domestic hybrids generally lack the
genetic muscle to withstand the pests
on their own. Thus the need for
insecticide, especially for sweet corn
production, notes Luthe's colleague,
W. Paul Williams. He is a plant
geneticist in the ARS Corn Host Plant
Resistance Research Unit at MSU,
near Starkville.
Weekly insecticide applications
can help ensure worm-free ears, he
says. But timing when to spray can be
a costly, hit-or-miss proposition.
Intrigued by the prospect of a natu-
ral alternative, the researchers pushed
their early investigations of the en-
zyme further-with help from other
researchers and graduate students.
In recent lab studies they used
molecular techniques such as PCR
(polymerase chain reaction) and
RFLP (restriction fragment length
polymorphism) to trace the enzyme to
an elusive gene, Mirl. Until then, this
gene had only been found in callus
tissue cultures from two corn germ-
plasm lines, Mp 704 and Mp 708, that
were developed at Mississippi State.
In spring of 1996, ARS and MSU
applied for a patent on the Mirl gene

and its enzyme, 33 kd cysteine pro-
teinase. Now Luthe says, "We're in
the process of negotiating an option
agreement with DeKalb Genetics to
explore commercial potential." The
agreement would allow the company
to insert the gene into greenhouse
plants and regenerate them to study
Mirl's insecticidal properties.
The scientists envision their
newfound enzyme would serve as a
built-in caterpillar deterrent in corn
and maybe even cotton. "If this is
something that proves to be worth-
while, it could be possible to increase
the plant's concentration of the
enzyme," says Williams.
That would ensure a caterpillar
ingests a high enough dose that it
either stops feeding or doesn't cause
further serious harm. Lab and field
studies suggest this could
mean fewer than 50 percent of BARRY
the pests survive to adulthood.
On another front, the Mirl
gene's enzyme could replace
or prolong the effectiveness
of toxin-making genes from
the bacterium Bacillus
Bt's genes now protect
commercial lines of
bioengineered corn and
cotton from boll worms,
tobacco budworms, and
other caterpillar pests. But
concern that pests are
genetically adapting to
tolerate Bt's toxins has
fueled a search for alter-
natives and counterstrate-
gies. Among these is
gene-stacking, or putting
more than one resistance
gene into a plant.
"It's possible that if Fall armn w
you could combine these their norma
Mirl gene fj
different genes," says 704 and 708

Williams, "you could slow develop-
ment of resistance in the insects."
So how long until new, worm-
resistant corn hits the farm field?
Possibly 2 or 3 years-if ongoing
research and commercial interest
hold course. "It's only going to come
if we can provide the gene and
associated technology to the seed
companies," Williams says. They
would "move this from research into
reality."-By Jan Suszkiw, ARS.
W. Paul Williams is in the USDA-
ARS Corn Host Plant Resistance
Research Unit, Box 9555, Mississippi
State, MS 39762; phone (601) 325-
2735, fax (601) 325-8441, e-mail *


orsin may grow to only half
I inch-and-a-half size if the
rom corn germplasm lines Mp
can be bred into commercial

Agricultural Research/June 1997

Agricultural engineer uaie VVwIKs (leit) ana tecnnician Koger .onler lOOK Ior water leaks
along the border of a test plot under a rainfall simulator.

N nature has a perfect recipe to
promote severe erosion in
the wheat-growing areas of
the Pacific Northwest.
First, freeze the top several inches
of soil so water can't infiltrate. Then
send a warm Chinook wind to melt
the surface, as well as any snowcov-
er. Finally, shower the ground with
small, gentle raindrops and watch the
thawed soil slide down the region's
steep slopes.
"Erosion in much of the country
results from heavy rainfall loosening
the soil and carrying it away," says
Agricultural Research Service
hydrologist John D. Williams. "But
in the Palouse area of eastern Wash-
ington and Oregon and western
Idaho, it's melting snow and light-

intensity rainfall that carry the soil
downhill. That's because the water
can't soak into the underlying frozen
soil." Williams works at the Colum-
bia Plateau Conservation Research
Center in Pendleton, Oregon.
"Rain on frozen ground is like
dumping water on a dinner plate,"
says eastern Oregon wheat farmer
Clinton Reeder. "Finding a manage-
ment strategy that keeps the soil in
place is tough."
A further complication: Much of
the area receives only enough
moisture to support a crop every
other year. So on nearly 4.5 million
acres of the Palouse, farmers like
Reeder grow winter wheat one year
and leave the land fallow the next, to
collect water. Crop stubble or residue

holds the soil in place for much of
the fallow period.
The soil's most vulnerable time
comes right after the next winter
wheat crop is planted-around
September. The soil's water content
is high, so it can't absorb much even
before freezing, and the surface is
protected only by scant residue and
tiny wheat seedlings. Annual soil
losses frequently reach 50 tons per
acre and have been as high as 150.
A grueling new experiment on
Reeder's land may help growers de-
termine the best tillage system to
hold the soil and nutrients in place.
To find accurate answers, Will-
iams reasoned that they had to run
their tests under natural-in this case
freezing-conditions. The business

Agricultural Research/June 1997

attire for the experiment days consist-
ed of thermal underwear; insulated
rubber boots, coveralls, and gloves;
ear muffs and hats; and rain gear.
They also need special equipment.
Machines that simulate rainfall are
commonly used for erosion experi-
ments. But most produce high-
intensity rain with large drops. So in
the 1970s, scientists with ARS, the
University of Idaho, and the Univer-
sity of Wisconsin developed special
rainfall simulators for the Pacific
"Those simulators produced the
right type of rainfall, but they were
designed to measure how much water
infiltrates the soil over a small, 3-
foot-square plot, rather than measure
runoff on a long plot," says ARS
agricultural engineer Don K. Mc-
Cool. Based at the Land Manage-
ment/Water Conservation Research
Unit in Pullman, Washington,
McCool worked on both the 1970s
machine and Williams' new model.
The current design consists of a
tentlike structure measuring 10 feet
tall by 10 feet wide by 40 feet long.
Inside, specially calibrated nozzles
drop water on the soil below. Lines
supplying electricity and water keep
the nozzles, monitoring equipment,
and water supply tanks running. In
all, it takes 4 people 8 hours to set up
the rainfall simulators and 12 people
to run the experiment simultaneously
on four adjacent plots.
"Everybody helps-the computer
specialist, administrative officer,
shop foreman, and anybody else
who's available," Williams says. In
addition to soil loss, ARS soil scien-
tist Clyde L. Douglas, Jr., measures
the nitrogen and phosphorus runoff.
The simulators have been run five
times over the past 2 years. The
experiments compare moldboard
plowing and rod weeding, chisel
plowing, and a new technique called

The mow-plow is a cross between
traditional and conservation tillage.
It's a moldboard plow pulled by a
tractor that has a modified combine
header on its front. The machine
harvests the old standing straw in
front of the tractor and conveys it to
the rear, just-plowed area, covering
the soil surface with residue. The
experiment tests the mow-plow
system on plots with light straw and
heavy straw.

Hydrologist John Williams checks a
clogged or frozen water emitter in the
portable rainfall simulator.

Moldboard plowing is a time-
honored technique that buries the
weed seeds, but it also deeply buries
straw left after harvest. "In erosion-
prone areas, crop residue is one of the
farmer's best methods for keeping the
soil in place," says ARS agricultural
engineer Dale E. Wilkins. He is also
at the Pendleton location.
"The chisel plow incorporates 90
percent of the residue in the top 4
inches and is a widely used conserva-
tion tillage technique. The drawback

is that it leaves weed seeds on or near
the surface, where they can emerge,"
he says. Annual weeds like downy
brome can significantly reduce wheat
yields-up to 90 percent in experi-
mental plots.
Preliminary results indicate that the
heavy-residue mow-plow system
provides the best combination of
nutrient and soil conservation and
weed control.
"This system could be especially
useful for farmers who have been
using conservation tillage but are
starting to have a problem with
downy brome," Wilkins says. "The
next step is to identify the best
conditions for using the mow-plow
system; that is, where sufficient crop
residue can be cut and moved onto
plowed soil to provide adequate
erosion control."
Reeder, who helped out during one
of the recent trials, was impressed
with the research.
"If you farm for long in this
country, you know frozen ground
leads to our worst erosion problem.
But when I watched the soil running
off in the experiment, the problem
really hit home," he says.-By
Kathryn Barry Stelljes, ARS.
John D. Williams, Dale E. Wilkins,
and Clyde L. Douglas, Jr., are at the
USDA-ARS Columbia Plateau
Conservation Research Center, P.O.
Box 370, Pendleton, OR 97801;
phone (541) 278-3292, fax (541) 278-
3795, e-mail
williajo @
Don K. McCool is in the USDA-
ARS Land Management/Water
Conservation Research Unit, Wash-
ington State University, 253 L.J.
Smith Hall, Pullman, WA 99164-
6120; phone (509) 335-1347, fax
(509) 335-7786, e-mail *

Agricultural Research/June 1997

DNA Fingerprinting of Rice


DNA analysis, now a frequent courtroom evidence
tool, is being fine-tuned by an Agricultural Research Ser-
vice scientist as a faster way to develop and "fingerprint"
new rice and wheat varieties to feed a hungry world.
"The world population is increasing at the rate of 96 to
100 million people each year-or nearly the size of
another Mexico City every 12 weeks," says J. Perry
Gustafson. He is a plant geneticist at Columbia, Missouri.
"We urgently need to improve cereal varieties by
getting more genetic diversity into them," he says.
"That's why finding and manipulating new specimens of
food crops like wheat and rice is so important. Without
being able to identify, increase, and use this diversity, the
world could eventually run out of food."
Gustafson, working with University of Missouri grad-
uate student Zongmin Zhou, from the People's Republic
of China, recognized that humans share a 15-base-pair se-
quence of DNA with wheat, rice, and mice. Zhou used
the knowledge to develop DNA fingerprint probes capa-
ble of distinguishing among rice and wheat varieties.
The researchers also used the common sequence to
isolate others that produce a DNA fingerprint capable of
both identifying and cataloging genetic differences within
rice and wheat. They were the first in the world to use a
single DNA sequence to distinguish between more than
80 rice varieties from the United States, the Philippines,
and the China.
For plant breeders, DNA fingerprinting can be a quick
way to select parents with the widest range of genetic
Currently, breeders must use a "cocktail" of up to 40
RFLP (restriction fragment length polymorphism) probes
in order to make the same selection for breeding. A
single-fingerprint probe such as this one has the potential
to cut several years off development of new rice and
wheat varieties.-By Linda Cooke, ARS.
J. Perry Gustafson is in the USDA-ARS Plant Genetics
Research Unit, University of Missouri, 204 Curtis Hall,
Columbia, MO 65211; phone (573) 882-7318, fax (573)
875-5359, e-mail *

Geranium Virus Hard To

Identify, Easy To Spread

If those geraniums that looked so beautiful at the
nursery last spring just didn't bloom well or ever look
healthy in your yard, they may have had a virus or two.
"Viruses do not kill geranium plants, but some can
severely reduce vegetative growth by affecting leaves and
can reduce flower quality and marketability by deforming
blooms and causing color breaks or streaks," says ARS
plant pathologist Ramon L. Jordan. A plant virus expert,
he leads the Floral and Nursery Plants Research Unit of
the U.S. National Arboretum.
Jordan says confusion exists about the exact identity of
some of the 15 or so different viruses attacking
geraniums-a flower crop worth about $200 million a
year to U.S. growers. Geraniums, genus Pelargonium, are
one of the most rapidly expanding garden crops in the
United States.
Now Jordan, working with ARS plant pathologist Gary
R. Kinard, has developed new tests that use biotechnol-
ogy to detect two of the newer viruses: pelargonium line
pattern virus and pelargonium ringspot virus. The tests
take about 24 hours.
Jordan says the new tests will help ensure that both
exported and imported geranium plants-potted or in
beds-are free of the two viruses.
Over the last 18 years, Jordan has been pursuing and
identifying disease-causing viruses in ornamental plants,
vegetables, and trees. What's tricky about the geranium
viruses, he says, is the easy way they get around and the 1
to 3 weeks that it takes after infection for their symptoms
to appear.
"An infected plant in the greenhouse can be the source
of some viruses that can spread via water to the plant
sitting next to it," he says. "Other viruses are spread by
aphids, while tiny insects called thrips can transmit
viruses or carry infested pollen from infected plants to
healthy ones.
"Since geraniums are propagated mainly by taking
cuttings from established plants, this is likely the most
common method of virus spread."
Jordan is working on the other viruses that attack
geraniums, as well as those that cause severe problems in
such popular flowers as impatiens and gladiolus.-By
Hank Becker, ARS.
Ramon L. Jordan is in the USDA-ARS Floral and
Nursery Plants Research Unit, U.S. National Arboretum,
10300 Baltimore Ave., Bldg. 010A, Beltsville, MD,
20705-2350; phone (301) 504-6570, fax (301) 504-5096,
e-mail *

Agricultural Research/June 1997

Science Update

Less Irradiation Would Still Stop
Fruit Pests
Irradiation may become more
practical as a quarantine treatment to
keep fruit flies from spreading via
fresh produce shipments. Irradia-
tion-safe, very low levels of gam-
ma-ray energy-interrupts the
insects' development so they can't
reproduce. And new ARS studies
with grapefruit and Mexican fruit
flies indicate irradiation amounts
could be cut by half or more. With a
faster, cheaper irradiation treatment,
produce could arrive at the supermar-
ket sooner and retain more of its
harvest quality. These findings make
irradiation an even more feasible
alternative to methyl bromide, a
chemical scheduled for phaseout by
2001. In a pilot irradiation program
begun 2 years ago, Hawaiian papayas
and other tropical fruits are shipped
to the Chicago area. There, exposure
to 250 Grays (Gy) of gamma rays
ensures that no hitchhiking oriental
or Mediterranean fruit flies survive to
adulthood. But 250 Gy-applied on a
commercial scale-can damage
oranges, mangoes, grapes, and other
fruits. Recently, ARS scientists found
that much lower doses stopped
development of Mexican fruit flies.
Their tests with grapefruit indicate 50
Gy may be adequate if these pests are
hiding in fruit. Guy J. Hallman and
Donald B. Thomas, USDA-ARS
Subtropical Agricultural Research
Laboratory, Weslaco, Texas, phone
(210) 565-2647, e-mail and

Fat in Cow's Diet Helps Calves
Keep Warm
About 95,000 calves die each year
from cold stress. But extra fat in a
cow's diet for the last 6 weeks of
pregnancy could help the newborn
calf tolerate the cold. Preliminary test
results have shown this for the first
time. Researchers added safflower
with a high concentration of linoleic
fatty acid to the diets of 12 cows for
53 days before calving. Eleven other
cows ate a standard feed ration. For
the first 5 hours after birth, calves
were kept at room temperature. Then
they were put in a room at 320F for 2-
1/2 hours. Calves whose mothers ate
the extra fat maintained their body
temperature better than did calves of
cows fed the standard diet. The
scientists believe the warmer calves
had more brown fat, which surrounds
organs such as kidneys and helps the
animals generate body heat immedi-
ately after birth. Researchers are
repeating the experiment and hope to
determine the significance of fat-
influenced body temperature differ-
ences. Robert Bellows, USDA-ARS
Fort Keogh Livestock and Range
Research Laboratory, Miles City,
Montana, phone (406) 232-4970.

Computer Model Helps Grain Stay
Too Cool for Bugs
Warm grain is prime breeding
ground for rusty grain beetles,
particularly in bins of more than
3,000 bushels. But cooling stored
grain with automated fans can
suppress the insects' development
and reproduction. This can reduce or
eliminate the need for insecticide.
ARS entomologists have developed
a computer model, Stored Grain
Advisor (SGA), to help growers and
others determine when to use cooling
fans as well as other tactics to
suppress rusty grain beetles and
lesser grain borer, two of the most
common stored-grain insects.
According to computer simulation
studies, fans should be turned on
when the air temperature is at least
18F cooler than the grain tempera-
ture. This can hold insect numbers
below damaging levels as far south
as Oklahoma. It also saves energy
and grain weight loss, because the
fans turn on only when necessary.
The SGA requires a computer with
Microsoft Windows 3.1 or later.
Farmers and grain elevator operators
can get the software through the
extension programs of Kansas,
Oklahoma, and Montana State
Universities. More details about
SGA can be accessed on the World
Wide Web at http://
Paul W. Flinn, USDA-ARS U.S.
Grain Marketing Research Labora-
tory, Manhattan, Kansas, phone
(913) 776-2707, e-mail

Agricultural Research/June 1997

U.S. Department of Agriculture
Agricultural Research Service
Room 408
6303 Ivy Lane
Greenbelt, MD 20770

Official Business
Penalty for Private Use $300

To stop mailing II
To change your address __
Please return the mailing label from
this magazine.

PO BOX 110240

-- - -- -- -- - - -- - -- -- -- -- - -
Superintendent of Documents Subscription Order Form
Order Processing Code: Charge your order. Fnk
6399 It's Easy! 1 =
To fax your orders (202) 512-2250
To order by phone (202) 512-1800
FA YES, enter my subscription as follows:
subscriptions to Agricultural Research for $29.00
per year ($36.25 foreign).
The total cost of my order is $ Price includes regular
domestic postage and handling and is subject to change.

(Company or personal name) (Please type or print)

(Additional address/attention line)

(Street address)

ZIP(Daytime phone including area code)
(Purchase order No.)
For privacy protection, check the box below:
SDo not make my name available to other mailers

Please choose method of payment:
-] Check payable to the Superintendent of Documents
-] GPO Deposit Account I I I I I I I 1I-[D
[ VISA or MasterCard Account

Exp. date
(Authorizing Signature)
Mail To: New Orders, Superintendent of Documents
P.O. Box 371954, Pittsburgh, PA 15250-7954

s Paid

A research update on
global climate change and
how it may affect plant and
animal agriculture.

A new computer model
helps farmers and others
better understand how
farming operations change
the environment.

Each year, about
400,000 bales of cotton
break open accidentally. An
agricultural engineer with
the Agricultural Research
Service has found a better
way to repair the bales.


University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs