Group Title: Agricultural research (Washington, D.C.)
Title: Agricultural research
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Permanent Link: http://ufdc.ufl.edu/UF00074949/00019
 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: August 1998
Frequency: monthly[1989-]
bimonthly[ former jan./feb.-may/june 1953]
monthly[ former july 1953-198]
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regular
 Subjects
Subject: Agriculture -- Periodicals   ( lcsh )
Agriculture -- Research -- Periodicals   ( lcsh )
Agriculture -- Periodicals -- United States   ( lcsh )
Agriculture -- Research -- Periodicals -- United States   ( lcsh )
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periodical   ( marcgt )
 Notes
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).
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Bibliographic ID: UF00074949
Volume ID: VID00019
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
















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FORUM


Biocontrol
Innovations
For a process so simple in nature-
a seed germinates in the soil and
grows into a fruitful plant-getting a
healthy crop up and keeping it going
can be an astonishingly complex task.
That's because crop plants have a
multitude of enemies, seen and un-
seen. The most obvious enemies are
the bugs-everything from borers that
burrow into a plant's stem and wreak
havoc from the inside out, to grass-
hoppers whose appetites have been
known to extend to fenceposts and
tractor tires.
Perhaps even more baffling are the
"new" enemies-viral and fungal cul-
prits that our farming ancestors could
see only in terms of the devastation
they left behind.
Of course, many of our new crop
enemies aren't new at all. Potato
farmers in recent years have been
again battling Phytophthora infestans,
the most destructive disease of pota-
toes worldwide. P. infestans is an
ancient foe; it's the same fungus that
repeatedly wiped out the Irish potato
crop in the 18th and 19th centuries.
Sometimes the enemy changes just
enough to confound control efforts-
again, P. infestans comes to mind.
Recently, a new, more virulent strain
of late blight, the disease caused by P.
infestans, has invaded the United
States.
Agricultural Research Service sci-
entists at Albany, California, are using
the latest biotechnology to study a
new experimental potato hybrid that
might carry genes for resistance to the
fungus. If the researchers can pinpoint
and clone the gene behind the hybrid's
disease resistance, they intend to
transfer it to commercial potato
varieties.
Cloning and moving genes are just
a few pieces in the big picture of bio-
control-finding ways to protect


plants other than with chemicals.
Many times, nature provides a prom-
ising weapon in the form of natural
enemies-from bacteria to wasps-
that can do battle against insect pests,
crop pathogens, and weeds, if only
we can discover the most effective
ways to use those weapons.
One of the most destructive crop
pests ever to arrive in America is the
silverleaf whitefly, Bemisia argenti-
folii, also known as biotype B of
sweetpotato whitefly, Bemisia tabaci.
This sap-sucking pest first appeared
on poinsettias in Florida greenhouses
in 1986. Within just 4 years, it had
spread to dozens of crops in year-
round farming regions of Florida,
Texas, California, and Arizona. Loss-
es caused by this tiny insect now run
as high as $500 million per year.
Now a fungus called Beauvaria
bassiana has proven highly effective
at stopping the whiteflies. In tests in
Weslaco, Texas, ARS scientists
showed that B. bassiana killed up to
90 percent of the immature pests in
small vegetable plots. Today B.
bassiana is available commercially in
a product called Mycotrol, the result
of a cooperative research and devel-
opment agreement between ARS and
Mycotech Corp. of Butte, Montana.
In this issue, you'll read how ARS
scientists across the country are pit-
ting their ingenuity against crop
pests. In North Carolina, the focus is
on Cercospora fungus, which attacks
a wide range of crops from corn to
soybeans. ARS scientists have found
that Cercospora carries around a vital
internal defense-a gene that protects
the fungus from its own poison.
Those scientists are now pursuing
whether that protective gene can be
put to work in crop plants.
You'll also read about ARS
researchers in California who've
come up with one of the most unu-
sual defensive maneuvers of all-
actually flinging beneficial insects


into fields aboard lightweight disks
that degrade naturally in rain or
irrigation water to unload their
predacious passengers.
The battle to protect crops without
chemicals has taken researchers
down roads undreamed of only a few
decades ago. One of the biggest chal-
lenges of pitting beneficial insects
against crop pests has been produc-
ing great enough numbers of the
beneficial.
Key to these efforts is a diet that
will sustain and nourish beneficial,
such as the Edovum puttleri parasitic
wasps that attack Colorado potato
beetles. ARS scientists in Colorado
have cooked up an artificial diet that
mimics the potato beetle eggs that
are the favored snack of Edovum
wasps and their offspring.
A special ingredient of that diet is
hemolymph-insect blood. The ARS
scientists are now searching for a
cheap, off-the-shelf substitute for
hemolymph, which harbors critical
substances that trigger the wasp
larvae's metamorphosis into adult
insects.
If the scientists succeed, the bene-
fits could be tremendous, both for
farmers and the environment. In tri-
als where 2,000 Edovum wasps were
released weekly in eggplant fields,
growers only had to spray chemicals
4 times during the growing season to
combat potato beetles-down from
the average 14 treatments.
"Chef to the bugs" was probably
not on any ARS researcher's original
list of career goals. But it's this kind
of innovative approach to biocontrol-
based crop protection that, in the
long run, is going to ensure that all
of us (and others around the world)
have enough to eat.

Sandy Miller Hays
Director, ARS Information


Agricultural Research/August 1998








August 1998
Vol. 46, No. 8
ISSN 0002-161X


A V ..... ,I ,,,;i R.A' p- Li,'J IS d III t'wil hl h\
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,rnd, M.Ilcr Ha!... lire tlor
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Agricultural Research




Spiders-the Ultimate Predator? 4

Blocking Sugarcane Borers 7

Routing Pecan Scab-Protecting a Popular Nut 8

Gene Turns Fungus Against Itself 1

BUGSLINGER! 12

Microbe Helps Evaluate Dietary Fiber 15

Earlier Castration Reduces Stress 15

Microbes Help Bees Battle Chalkbrood 16

Tailoring Rice To Suit Consumers 18

A Shot in the Dark 22

Microwaves To Measure Fruit Maturity 23

Old Virus Morphs Into New Chicken Threat 24

Science Update 27








Cover: Researchers are just beginning to evaluate the potential for native insect
predators-including spiders such as this long-jawed orb weaver-to hold
agricultural pests in check. Photo by Scott Bauer. (K8111-2)



In the next issue!


W USDA's plant explorers still face a challenging frontier both
politically and geographically as they improve the flavor and pro-
ductivity of many crops.

( ARS technology for low-temperature microscopy could find a
new theater of operations: the Red Planet's polar ice caps.

(w What do cranberries and the mustached mud bee have in
common? They are both American natives and soon they may
depend on each other.


Agricultural Research/August 1998










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SPIDERS

the Ultimate Predator?


R researchers investigate a
broad range of biological
tools for control of insect
pests. These include use of parasites,
pathogens, growth regulators, bio-
insecticides, and foreign predators.
Now, Agricultural Research
Service scientists are beginning to
exploit a vast reserve of untapped
potential-native predators, includ-
ing spiders, a neglected group of
biocontrol agents.
For example, when scientists
checked out a Georgia cottonfield
last year, they determined that about
one-fourth of the specimens of one
spider species had dined on eggs of
two cotton pests. In Colorado, they
conducted the first North American
survey for spiders that kill cereal
aphids and other wheat pests.
These predators belong to the ani-
mal phylum known as arthropods-
creatures with jointed legs, a seg-
mented body, and a hard exoskeleton.
"Arthropods make up the vast
majority of all known animal
species," says ARS entomologist
Matthew H. Greenstone. "They
include arachnids-the class that
includes scorpions, mites, and
spiders-as well as insects, centi-
pedes, and millipedes." Unlike
insects that have three pairs of legs,
arachnids have four pairs.
"In most agricultural ecosystems,"
says Greenstone, "arthropod preda-
tors are the most consistently present
and abundant natural enemies of
insect pests. But they have been
largely neglected, mainly because
their effectiveness has been difficult
to demonstrate."


Using a gasoline-powered insect vacuum,
technician Brian Jones samples the number
of spiders at various points in an Oklahoma
wheat field. The tubular extension prevents
crushing of wheat stems and enables the
airflow to be maintained for efficient
sampling. Photo by Scott Bauer. (K8116-1)


Greenstone works today at ARS'
Plant Sciences and Water Conserva-
tion Research Laboratory in Still-
water, Oklahoma. But he started his
investigations of native predators in
1982 in Columbia, Missouri, at the
agency's Biological Control of
Insects Research Laboratory. There
he pioneered new biochemical tests
to help scientists include these
predators in their biocontrol research.


Long-jawea ore weavers are aounaant
spiders in Colorado and Oklahoma wheat
fields. They feed on greenbugs, which are
serious pests of winter wheat.



He believes that the most efficient
and direct approach to gathering
long-term data on arthropod preda-
tion is serological analysis. This
means using antibodies-molecules
produced by white blood cells that he
grows in a special medium in his
laboratory incubator-in assays to
identify the remains of prey in a
predator's gut.
"These assays," he says, "must be
specific, because the gut may contain
not only target antigens-molecules
recognized by the antibodies-but


also antigens from other related
species. The assays have to be highly
sensitive, because the antigens often
occur in exceedingly small amounts,
sometimes less than a few millionths
of a gram.

Gut Assays While You Wait
Greenstone pioneered use of
monoclonal antibodies to analyze the
predator guts. Working with ARS
biological technician Clyde E.
Morgan at Columbia, Greenstone
used the spined soldier bug as a
laboratory model to develop a fast
ELISA (enzyme-linked immunosor-
bent assay) test. In just 2-1/2 hours, it
could detect remains of cotton boll-
worm larvae in the soldier bug's gut.
"This test, developed in 1982, was
the first to use a monoclonal antibody
to study predation," says Greenstone.
"It was also the first to distinguish
different growth stages of a single
caterpillar species, as well as related
caterpillar species."
The test distinguishes cotton
bollworms from their cousins, the
tobacco budworm and groundcherry
fruitworm. It also recognizes three
other caterpillar pests in the same
family-the fall armyworm, cabbage
looper, and velvetbean caterpillar-
along with the imported cabbage-
worm.
In 1990, Greenstone, working with
ARS microbiologist Melissa K.
Stuart at Columbia, perfected and
simplified the monoclonal antibody-
based predator gut content assays.
They developed a simple assay-
called the immunodot-that was less
expensive and faster than ELISA.
"The immunodot assay does not
require the elaborate and expensive
equipment needed for interpreting
ELISA assays," Greenstone says.
A few years later, Greenstone,
Stuart, and entomologist James H.
Hunt at the University of Missouri at


Agricultural Research/August 1998













St. Louis proved that the immunodot
assay worked with jumping spiders
and paper wasps, as well as with
soldier bugs.
"Such rapid, easily interpreted
assays make immunoassay technol-
ogy more accessible to arthropod
ecologists. That, in turn, is helping to
increase our knowledge of arthropod
predators' role in biocontrol," says
Greenstone. Since 1995, he has
continued this work in Stillwater.

Grower Alert
Last year, Greenstone and Univer-
sity of Georgia entomologist John R.
Ruberson collaborated on research
that will alert growers as to which
natural enemies are attacking bud-
worms and bollworms in cotton-
fields.
"Bollworms and budworms alone
cost southeastern cotton growers
several hundred million dollars a year
in damage and chemical controls,"
says Greenstone. "To make intelli-
gent pest management decisions,
growers need to know which natural
enemies are attacking these two
pests."
Ruberson collected more than
3,000 predatory insects and spiders
from a 30-acre cottonfield. The most
important predators were big-eyed
bugs, red imported fire ants, Scymnus
lady beetles, and a native winter
spider species, Chiracanthium
inclusum.
Ruberson analyzed the creatures
with the ELISA test, using Green-
stone's monoclonal antibody. He
found that 6.5 percent were positive
for budworm and bollworm egg
remains.
"This 6.5 percent appears low,"
Greenstone says, "but the egg num-
bers themselves were fairly low
during most of the season. Some
predators had high rates of egg
feeding, including 25 percent of the
winter spiders."


The assay and insect census data
will be combined to determine the
relative importance of each predator
in suppressing budworms and boll-
worms.


Entomologist Matthew Greenstone replen-
ishes growth medium for hybridomas, the
cultured white blood cells he uses to pro-
duce monoclonal antibodies to analyze the
gut contents of spiders and other arthropod
predators.


In Stillwater, Greenstone's new
focus is biological control of cereal
aphids. He and ARS biological
technician Brian G. Jones recently
completed the first quantitative
survey of spiders in winter wheat in
North America.
"Very good data from Great
Britain and northern Europe show
that spiders can help to control
aphids in wheat and barley fields in
those countries," says Greenstone.
"Surprisingly, nobody had looked at
spiders in these crops on this
continent.


"We surveyed winter wheat fields
in southeastern Colorado and uncov-
ered a spider fauna much more
diverse than those reported in Great
Britain, Northern Europe, and New
Zealand. There, one family of
spiders-Linyphiidae, the line- or
sheet-web weavers-dominates.
In Colorado, Linyphiidae consti-
tuted just one-fifth of the spider
individuals. Six other families each
made up 10 percent or more," says
Greenstone.
"Now that we know the spiders,
we need to develop the tools to
perform gut analysis to detect Rus-
sian wheat aphids, greenbugs, and
other important aphids in wheat and
barley. Then we'll be able to com-
bine gut and census data and deter-
mine which spiders and other arthro-
pod predators are most important in
wheat and barley fields."
Today, in collaboration with an
independent antibody-producing
facility at Oklahoma State Univer-
sity, Greenstone is developing
monoclonal antibodies to detect the
remains of three major cereal
aphids-the greenbug, Russian wheat
aphid, and corn leaf aphid.
Another collaborator, William
O.C. Symondson of the University of
Wales in Cardiff, is developing
monoclonals for the English grain
aphid, bird cherry oat aphid, and rose
grass aphid.
"With these six antibodies,"
Greenstone says, "we will be able to
study the role of predators in sup-
pressing cereal aphids in many parts
of the world."-By Hank Becker,
ARS.
Matthew H. Greenstone is at the
USDA-ARS Plant Sciences and Water
Conservation Research Laboratory,
1301 N. Western St., Stillwater, OK
74075; phone (405) 624-4119, fax
(405) 372-1398, e-mail
mattg@ag.gov *


Agricultural Research/August 1998









Blocking Sugarcane Borers


F or all its towering height and
tough, bamboo-like stalk,
sugarcane can easily succumb
to a small insect pest called the
sugarcane borer, which chews
hungrily into the plant's core-and
growers' profits.
In Louisiana, scientists are work-
ing hard to undermine the borer with
12 new strains of sugarcane germ-
plasm that naturally resist or
tolerate its destructive


tunneling. By crossing
these borer-resistant strains
with commercial cultivars,
they hope to ease the need
for using insecticides.
"The borer is the most
important insect pest of
sugarcane in Louisiana and
probably Florida, too," says
William H. White, an Agri-
cultural Research Service
entomologist involved in
the project.
While effective, insecti-
cides add to growers' pro-
duction costs and pose an
environmental danger. Lou-
isiana's many waterways
make this "a highly visible
concern," says White, who
is in ARS' Sugarcane Re-
search Unit at Houma. His
lab sits on the edge of sug-


recurrent mass selection. It calls for
screening thousands of cane plants
from many different parental lines.
Plants that best withstand borer
attack are selected out and crossed
with other hardy survivors. This is
repeated many times to strengthen
resistance traits in progeny.
"Gradually," says White, "you
start shifting the average level of


WILLIAM WHITE (K8143-1)


arcane country in southern Louisiana,
where about 35 percent of the na-
tion's $1.5-billion crop is grown.
White's cane-breeding ARS
colleagues are Benjamin L.
Legendre, Jimmy D. Miller, and
David M. Burner, along with
Louisiana State University's Thomas
E. Reagan and Scott B. Milligan.
Legendre heads the Houma lab, and
Burner is a geneticist there. Miller
leads ARS' Sugarcane Research
Station in Canal Point, Florida.
To develop borer-resistant sugar-
cane, they used a process called


resistance a little bit higher each
time."
Of the 12 germplasm lines-or
clones-the breeders developed, one
called US93-15 showed some of the
highest resistance levels. When
deliberately exposed to borers in field
plots, that line's stalks suffered 85
percent less internodal damage than
susceptible commercial cultivars.
A grower's battle against the pest
begins soon after it hatches from eggs
laid on leaves. At that point, insecti-
cides are the hardest-hitting weapon.
But growers use them sparingly,


relying instead on help from parasitic
wasps and predatory insects.
"It's a race," says White of their
efforts to battle borers by such
chemical and biological means. For
once the larva tunnels into the stalk,
it can feed, grow, and pupate in
relative safety.
On susceptible cultivars, borer
numbers can soar to levels that inflict
serious economic harm.
One indicator of danger-
ous levels: If scouting
shows 1 out of 20 stalks of
a susceptible variety to be
infested, then a grower
might want to consider
spraying to prevent
significant economic loss.
But White says, "We
know some cultivars have
harder rinds that prevent
the larvae from getting
into the stalk quickly."
Such traits help "raise
the economic threshold
before insecticides are
recommended. And,
you're buying time to al-
low your beneficial in-
sects to catch up."
This fits in well with
integrated pest manage-
ment in which chemical,
biological, and cultural
controls are used in concert. In
Louisiana, IPM programs have
helped growers reduce their insecti-
cide use. Instead of four to five
applications per acre each season,
they are averaging less than two.-
By Jan Suszkiw, ARS.
William H. White, Benjamin L.
Legendre, and David M. Burner are
in the USDA-ARS Sugarcane Re-
search Unit, 5883 USDA Rd.,
Houma, LA 70360; phone (504) 872-
5042, fax (504) 868-8369, e-mail
white @ nola.srrc.usda.gov *


Agricultural Research/August 1998








Routing Pecan Scab-

Protecting a Popular Nut


weet, tasty pecans remain
one of the most popular
foods native to North Ameri-
ca. Last year, U.S. consumers ate 134
million pounds of them.
But this staple of pies and ice
cream and other confections faces a
tiny, yet powerful enemy: pecan scab
disease. If unstopped, the fungus can
destroy a crop, forcing food com-
panies to import pecans to meet
demand.
Agricultural Research Service sci-
entists Bruce W.
Wood and Charles ROB FLYNN (K8122-1)
C. Reilly are doing 5D.
their part to ensure
that consumers have
an adequate supply
of pecans. Wood, a
horticulturist, and
Reilly, a plant path-
ologist, work at the
ARS Southeastern
Fruit and Tree Nut
Research Laborato-
ry in Byron, Geor-
gia. There, they are
developing new
strategies to combat
pecan scab and pro-
tect this native nut
crop.
Wood, who heads Horticulturist Br
the Byron lab, says greenhouse plant
two of the main
advances leading to the U.S. pecan
industry's success have been the
introduction of fungicides and
airblast spray technology for quickly
and effectively dispersing pesticides
throughout an orchard.
"We're studying ways to build and
improve on these advances," he says.
"The approaches have quadrupled
yields and boosted farmers' profits.
But they've also increased operating
costs, at a time when wholesale
prices for pecans have declined. So
we're developing ways to effectively
control scab while reducing spraying


costs and minimizing environmental
impact."
Pecan scab, caused by the fungus
Cladosporium caryigenum, is gener-
ally the most damaging pecan
disease. Discovered on pecans in
1888, it started to become a problem
in the early 1900s, when farmers first
domesticated the crop.
Scab attacks the foliage, twigs, and
developing fruit. The disease causes
lesions to appear on leaves as small,
charcoal gray to black, concentric


uce Wood (left) and plant pathologist Charles Reilly
s for pecan scab damage.

circles. Severe infection causes
defoliation, fruit abortions, and
poorly filled fruit, thus reducing
yields. It is active throughout the
growing season and, if left un-
checked, can cause near total crop
losses.
The disease continues to be a
problem, particularly for the primary
commercial pecan tree varieties-
Desirable, Schley, and Stuart-
grown in the Carolinas, Georgia,
Alabama, Florida, Mississippi,
Louisiana, and east Texas, where the
climate is generally moist. Pecan


scab is not a problem in arid western
regions, like New Mexico, Arizona,
and California. Overall, it costs
pecan growers at least $22 million
each year in losses and control costs.

Holding the Threat at Bay
Current scab control strategies
often require 9 to 11 fungicide
sprays per season. Growers typically
spray first when leaves begin to
emerge from swelling buds, around
the first or second week in April.
But scientists
have found that
young leaves
emerging from
breaking buds in
the spring are not
vulnerable to scab.
It is after the
leaves have grown
for about 10 to 14
days that foliage
becomes suscepti-
ble, Reilly says.
"This means
that growers can
abbreviate their
spray schedule by
eliminating or
delaying the
inspect typical first spray.
This could save
about $15 to $18
an acre in control
costs and also cut pesticide use."
Reilly says weather conditions are
the driving force in scab infection
and that the disease worsens during
periods of high rainfall. "We're
developing new predictive spray
methods, so growers can potentially
reduce costs and pesticide use by
cutting the spray schedule during
dry years," he says.
Grower complaints of substantial
crop losses to scab-even though
their orchards received several
fungicide sprays per year--have


Agricultural Research/August 1998













raised suspicions about emerging
scab resistance to fungicides.
"We haven't been able to prove
increased resistance," says Reilly.
"But we have discovered major
deficiencies in the timing and
techniques of fungicide application
that may give the false impression of
resistance."
To the scientists' surprise, Reilly
says, they discovered the disease
protection from fungicides only lasts
about half as long as the 2 to 3 weeks
previously assumed. "Standard
control strategies traditionally used
in commercial orchards leave
developing fruit unprotected from
scab about half of the time," says
Reilly.
A second discovery was that the
approximate 4-day kickback
activity-the fungicide's ability to
kill scab after infection-was closer
to being nonexistent for most
fungicides, under commercial field
conditions.
"This new information will allow
growers to adjust spray strategies to
spray orchards quickly once infec-
tive conditions develop, or to spray
before conditions are right for the
disease to take hold," Reilly says.

Better Spray Coverage
A major scab control problem for
pecan growers is the time required to
spray an entire orchard. Airblast
sprayers typically used in orchards
carry 500 or 1,000 gallons of fungi-
cide, travel about 2 miles an hour,
and deliver about 100 gallons of
spray per acre. This restricts spray
coverage to about 75 acres a day.
Many commercial pecan orchards
are over 400 acres and require more
than one airblast sprayer to protect
the crop in a timely manner.
To measure fungicide application,
the researchers studied how much
and where spray materials were


being deposited in the trees, some of
which are up to 70 feet tall.
"We discovered that a primary
reason for poor scab control was
uneven coverage," says Wood. "The
top third of the tree receives very
little spray, and coverage of the
lower two-thirds is often excessive."
The scientists concluded that con-
temporary spray equipment contrib-
utes to scab-related losses because
foliage and fruit are often poorly
covered by pesticides.
Wood and Reilly are evaluating a
new nozzleless sprayer developed by
Michigan State University research-
ers that will allow for improved
protection against disease and insect
pests. The sprayer penetrates the tree
canopy better, while reducing spray
volumes by one-half to two-thirds.
"Preliminary evaluation of this
new spray technology for pecans
appears highly promising," says
Reilly. "The strategy includes use of
an atomizer that creates uniform
droplet size, giving superior penetra-
tion of fungicides carried by a high-
energy airstream into the tree cano-
py. The nozzles on traditional
sprayers either clog up or wear out,
causing a need for frequent inspec-
tion and replacement.
"On average, growers produce
about 286,000 million pounds of
pecans per year," Reilly says.
"They're very excited about having
new scab control strategies that
lessen crop losses and save money,
while reducing pesticide usage."-
By Tara Weaver, ARS.
Bruce W. Wood and Charles C.
Reilly are at the USDA-ARS South-
eastern Fruit and Tree Nut Research
Laboratory, P.O. Box 87, Byron, GA
31008; phone (912) 956-6420, fax
(912) 956-2929, e-mail
a03bwood@ attmail. com
a03nuts@attmail.com *


If unchecked, lesions like these caused by
pecan scab can lead to tree defoliation and
reduced yields.


ROB FLYNN(K8125-1)


This new nozzleless sprayer uses one-half to
two-thirds less spray to achieve superior
coverage and penetration of the tree
canopy.


Agricultural Research/August 1998







Gene Turns Fungus

Against Itself


A clever killer lives in the
cornfield, hiding in dried
husks of dead plants. His
weapon: a poison so deadly even he
could succumb to its toxic powers
without a means of self-protection.
But someone got wise to the killer's
game-and stole his secret to protect
the innocent.
It sounds like a plot from film noir.
But this detective story took place in
a laboratory. The investigators were
plant pathologists Greg Upchurch,
with USDA's Agricultural Research
Service, and Jon Duvick, with
Pioneer Hi-Bred International,
Incorporated.
The villain was a group of fungi in
the genus Cercospora. These micro-
bial miscreants secrete the toxin cer-
cosporin, which allows them to feed
on plant tissues. Cercospora fungi
cause disease on many crop plants,
including grey leaf spot on corn and
purple seed stain on soybeans.
But growers are the real victims.
Grey leaf spot can take 5 to 50 per-
cent of a crop's yield. In 1996, rough-


ly 80 percent of the cornfields in cen-
tral and southern Illinois were hit.
No-till cultivation, a must for saving
soil from erosion, unfortunately gives
this fungus more opportunity.
At the ARS Soybean and Nitrogen
Fixation Unit in Raleigh, North Caro-
lina, Upchurch and his research team
isolated and cloned a gene that pro-
tects Cercospora fungi from their
own toxin. The scientists determined
the gene's function by inactivating it
through mutation. In the presence of
toxin, their mutant strain with the
nonfunctioning gene had 60 percent
less growth than a strain with an in-
tact protective gene.
It appears the gene is responsible
for making a protein that pumps the
toxin out of fungal cells. Upchurch's
research team named the protein "cer-
cospora facilitator protein," or CFP.
Could the fungi's secret weapon be
turned into a plant protector, they
wondered?
Finding the answer was critical. Al-
though Upchurch's talented team dis-
covered the unique cfp gene, getting it


Plant pathologist Greg Upchurch inspects tobacco plants inoculated with Cercospora
nicotianae fungi for evidence of lesions indicating infection.


transferred into corn would take the
skills of researchers at Pioneer.
"Many companies are looking for
genes to put into plants for various
reasons, and they have the skills and
expertise to move these genes into
crops," says Upchurch. "But finding
specific genes can mean a lot of basic
research, and this may not be an op-
tion for every company."
"We have our own large gene dis-
covery group," says Pioneer's Du-
vick. "But when we hear about good
research with real potential, we're al-
ways interested. No one company or
research project will be able to dis-
cover all the genes."
The two scientists embarked on a
cooperative research and develop-
ment agreement that allows them to
perform several joint research
projects. Their goal: to determine
whether the gene for cercosporin re-
sistance can be used to protect other
organisms. The agreement allows
both partners to do more with their
scientific resources.
"Information and materials being
exchanged under this agreement give
us another approach to our corn dis-
ease programs," says Roger Kemble,
Pioneer's research director for crop
protection. "We are pleased to work
with USDA on this project."
To transfer a useful gene into
crops, scientists must:
First show that they can move the
gene from organism to organism, a
process called transformation;
Be sure the new host organism
adopts the new gene as part of its own
genetic programing. In the case of the
cfp gene, it means knowing that hav-
ing the gene causes the new host or-
ganism to make the CFP protein;
Prove that the new gene is effec-
tive-that it reaches plant leaves and
wards off the toxin's effects; and
Test the gene as part of the
plant's total genetic package in the
field.


Agricultural Research/August 1998













Since corn is such a complex
organism, a simpler one was sought
for transformation and initial testing.
Although brewers yeast is a favored
organism for plant biotechnology, it
seems to naturally resist cercosporin.
Upchurch found that the cercosporin-
vulnerable fungus Cochliobolus
heterostrophus fit the bill.
C. heterostrophus transformed
with the cfp gene did show resistance
to cercosporin-a good omen for the
gene's potential use in plants includ-
ing new corn or soybean hybrids.
Achieving transformation and ef-
fective protection in C. heterostro-
phus gave Upchurch confidence to try
putting the gene in tobacco plants, the
classic "lab rat" of plant science. Pio-
neer Hi-Bred researchers began in-
serting the gene in corn.
Upchurch used a small piece of
bacterial DNA called a plasmid vec-
tor. This plasmid vector served as a
molecular "bus" to carry the cfp gene
into plant cell nuclei. A culture of
Agrobacterium containing cfp plas-
mid was used to infect the plant and
transmit the cfp gene so that it could
be incorporated into the plant's genet-
ic programing. Although this tech-
nique can be used for many plants, it
doesn't work well in corn.
To get the gene into corn, Pioneer
brought a more recent innovation, a
gene gun, to the investigative team.
Corn can be more of a challenge to
change genetically-that's why the
gene gun was needed.
"There's probably no single reason
why genetic transfer should be harder
with plants like corn," said Duvick.
"Someday, we'll probably find out
that it's many unrelated things-
that's how complex the plants are."
After the gene was transferred, Up-
church and Duvick needed to be sure
their respective plants were actually
making the protective protein. For
this, Upchurch produced special anti-
bodies to detect CFP in plants.


Soybeans with purple seed stain caused by Cercospora kikuchii rest on a printout showing
the genetic code for cercospora facilitator protein.


The antibodies are specific pro-
teins that bind to the CFP protein
much as human antibodies do with
cold viruses. Producing antibodies in
nature is a standard laboratory tech-
nique used in medicine and plant
science. Upchurch's team got the
antibodies by using fragments on the
CFP protein that they suspected
would trigger antibodies in an ani-
mal. These antibodies allowed them
to confirm that the CFP protein was
present in tobacco and corn.
But having CFP present is not
enough. It has to be actively working
in place in cells to protect the plant.
Pioneer plans to test CFP corn in
a greenhouse and in test fields.
Armed with this new genetic shield,


it will soon meet Cercospora when
scientists expose the corn to this fun-
gal crop killer.
"This is only the first of many
tests," says Duvick. "If it shows
promise, we'll still have a long way to
go. Good science isn't based on the
evidence of a single summer's
data."-By Jill Lee, ARS.
Greg Upchurch is in the USDA-
ARS Soybean and Nitrogen Fixation
Research Unit, P.O. Box 7616, De-
partment of Plant Pathology, North
Carolina State University, 2416
Gardner Hall, Raleigh, NC 27695;
phone (919) 515-6996, fax (919) 515-
7716, e-mail
gregupchurch @ ncsu.edu *


ROB FLYNN (K8142-1)


I.
When lesions caused by Cercospora nicotianae occur in large numbers, such as on
this tobacco leaf, they cause significant leaf tissue death.


Agricultural Research/August 1998






BUGSL SINGER!
KEN HACKMAN (K8117-6)
Flings Biocontrols Where You Want 'Em


Agricultural Research/August 1998














C coming soon to a farm near
you: six- and eight-legged
creatures that arrive in
flying saucers and fan out to devour
or otherwise demolish their living
prey...cotton aphids and other farm
pests.
The craft isn't a spaceship. It's the
Bugslinger, or Aerodynamic Trans-
port Body, one of two new devices to
help farmers deploy beneficial, pest-
killing insects and mites to exactly
where they're needed in fields.
The new devices do this more
quickly, easily, and economically
than others tested by the scientists.
Bugslinger, or ATB, and its partner
in biocontrol, the Mite Meter, should
boost the use of good bugs and
reduce growers' reliance on
chemicals.
Agricultural engineer Lyle M.
Carter and his Agricultural Research
Service colleagues in California
invented the devices for strategically
scattering the beneficial insects.
They are currently testing and
refining both the Mite Meter and the
ATB.
Carter, agricultural engineer
Joseph H. Chesson, and machinist
John V. Penner are based at ARS'
Western Integrated Cropping Sys-
tems Research Unit in Shafter.
They're seeking a patent for the
ATB. It's an innovative modification
of targets used in skeet or trap
shooting. The beneficial organisms-
which are either predators or para-
sites of crop-destroying insects-
travel in a lightweight, disk-shaped
container launched from the edge of
the field. The disk has a suitably
sized exit for the beneficial to use
once their mothership lands.



Agricultural engineer Lyle Carter uses a
standard clay pigeon launcher to propel
the Bugslinger disk into a newly planted
field.


"Right now," says Carter, "we're
working with a disk made of pow-
dered limestone that's about 4 inches
in diameter and 1 inch high. But
disks could also be made of materi-
als that degrade faster, such as paper,
oatmeal, tree bark, alfalfa hay,
compacted fertilizer pellets-or even
compressed peat moss like that used
for nursery pots. Any of these
alternative containers," he says,



KEN HACKMAN (K8118-11


The lightweight, biodegradable ATB
(Aerodynamic Transport Body) can be
loaded with insect predators or parasites.
This device will quickly distribute beneficial
insects throughout this field of young cotton.


"will deteriorate naturally after a few
rains or after the field is irrigated a
few times."

A Big Fling
The researchers' tests show that
even the delicate biocontrol wasp
Aphelinus nr. paramali survives the
disk's 110 mile-per-hour speed and
175G rotational force. The Apheli-
nus wasps attack cotton aphids, a
pest that also carries the costly citrus
tristeza virus.
The ATB launcher can be mount-
ed on a truck, tractor, or all-terrain
vehicle that would travel along field
roads, slinging saucers as it goes.


"That's much faster than manually
placing containers of biocontrol
agents near plants," notes Carter,
"and is comparable in application
time to ground spraying of insecti-
cides." Though any beneficial insect
or mite is a candidate for this special
shuttle service, it seems best suited
for use with adult predators or adult
parasites that can quickly fly away
from the container.
Because the launching device
operates from the perimeter of a
field, it reduces the number of times
workers would otherwise need to
enter the property. This lowers labor
costs, reduces soil compaction after
rain or irrigation, and helps thwart
the inadvertent spread of weed seeds
and pests that can cling to clothing or
machinery.

Bombs Away!
If the ATB is a catapult, the Mite
Meter is a gentle bomber that effi-
ciently and precisely dispenses
predatory mites or other beneficial.
The Mite Meter may boost use of
these commercially available preda-
tors by cotton growers, who don't yet
generally rely much on the tiny but
hard-working helpers.
The prototype Mite Meter consists
of a small, chilled holding tank for
the biocontrols. They rest within
vermiculite, corn grits, or other
carrier material. A tiny gate dispenses
precise amounts of the mite-and-
carrier mix onto a narrow conveyor
belt. The belt's speed is adjustable
with a small electric motor. On
reaching the end of the belt, the
mixture falls to the ground.
The Mite Meter can be attached to
a tractor to dispense 500 to 20,000
mites per acre across as many as 10
acres in an hour.
Carter and co-researchers at
Shafter tested the prototype with
western occidental mites, Galendro-


Agricultural Research/August 1998













mus occidentalis, and big-eyed bugs,
Geocoris punctipes. Both of these
predators eat Pacific spider mites,
strawberry mites, and two-spotted
mites. The big-eyed bug attacks
additional pests in cotton and other
crops, as well.
In outdoor tests, more than 95
percent of the beneficial mites and
big-eyed bugs survived a trip through
the Mite Meter. The apparatus can't
ferry beneficial wasps, however,
because they are too fragile.
Carter says the prototype Mite
Meter is superior to many other
devices for applying beneficial
because of speed, precision, and high
survival rate of mites. Too, the meter
enables growers to use mites straight
from the box, that is, the shipping
container from the insectary where
the mites were raised.
Much of Mite Meter's precision is
owed to the design of its tank. An
inner, 1.5-liter bottle-like the kind
soft drinks are sold in-fits into an
insulated jug. The jug is kept frozen
when not in use.

KEN HACKMAN (K8119-1)
-:A..::- .-.; ".


S.. '


Says Carter, "Keeping the mites
cool and comfortable is critical.
Otherwise, they move around quickly
in the tank, generally upward and
away from the gate and metering belt.
That means your application rate
might be too low at the beginning of
the run and too high at the end. You'd
have to buy extra mites to make up
for the inconsistent distribution."
Some mite applicators require
further diluting of an insectary's
mite-and-carrier mixture. Typically,
insectaries ship predaceous mites in
concentrations of from 1,000 to
20,000 mites per one-quarter to 1 cup
of carrier.
With the Meter, there's no need to
buy and mix any extra carrier. That
means there's no increased risk of
accidentally killing some of the
mites. Otherwise, the longer the mix
is tumbled, the greater the number of
mites that are inadvertently killed.
Both the Mite Meter and the ATB
should give commercial insectaries
the option to provide customers with
preloaded containers of beneficial


Agricultural engineer Joe Chesson (left), machinist Vic Penner (center), and agricultural
engineer Lyle Carter adjust the application level of the Mite Meter used to apply
predaceous mites in a newly planted cottonfield.


Attached to a tractor, the Mite Meter can
be calibrated to dispense from 500 to
20,000 biocontrol mites per acre.


that can be taken directly to the field
and dispensed.
"With the Mite Meter," Carter
points out, "you're working with a
small volume of mixture, instead of a
lot of bulky carrier. Because you're
applying the mites at insectary con-
centrations, you only need to refill the
tank every 2 hours or so. And you
don't need to stop to re-cool the
material. We estimate that all these
advantages might add up to a cost
savings of about 30 to 50 percent over
other approaches."-By Marcia
Wood, ARS.
For more information on patent
application number 08/933,124,
"Aerodynamic Transport Body for
Distribution of Biological Agents," or
on the Mite Meter, contact Lyle M.
Carter, USDA-ARS Western Integrat-
ed Cropping Systems Research Unit,
17053 N. Shafter Ave., Shafter, CA
93263; phone (805) 746-8004, fax
(805) 746-1619, e-mail
lcarter@lightspeed.net *


Agricultural Research/August 1998









Microbe Helps Evaluate Dietary
Fiber

Scientists at the Richard B. Russell Agricultural Re-
search Center in Athens, Georgia, brought in a small, new
consultant last summer for an inside job. The assistant was
microscopic and lived in people's intestines. It did not
shrink from its task: eating indigestible pieces of food. The
humble, mild-mannered microbe helped the scientists
identify the best foods for a high-fiber diet.
Nutritionists have long preached the gospel of including
fiber in the diet. It helps with weight control and may pro-
tect the colon from certain cancers. But everyone knows
fiber-rich diets can sometimes lead to bloating and gas.
Nutritionists are still debating which fiber will work
best with the least discomfort.
Perhaps a bacterium could provide some of the answers,
suggested Scott Martin, an anaerobic microbiologist with
the University of Georgia at Athens.
He shared his thoughts with Agricultural Research
Service microbiologist Danny E. Akin and chemist W.
Herbert Morrison at the nearby Russell center.
The trio began designing experiments to use bacteria
from the human gut to evaluate fiber quality.
The microbe they picked: Bacteroides ovatus. It is one
of the few human-dwelling, fiber-digesting bacteria that's
been isolated.
The researchers found that B. ovatus tore through oat
bran, dissolving almost 75 percent of a sample in 3 days.
That means the oat bran may not be the best fiber candi-
date. If fiber breaks down too quickly, it can't provide the
bulking and cleaning roles in the gastrointestinal system
that nutritionists say are critical to human health.
Maize or corn bran was slowest to break down, with 42
percent digestion over the same period. But slowest
breakdown may not be best to avoid the discomfort of
intestinal gas.
Wheat bran struck a middle ground.
Finding that balance in digestibility might someday
provide fiber supplements for consumers who can't deal
with a morning bowl of high-fiber flakes. Researchers said
they hope their initial work will be valuable to food
producers and nutritionists for this reason.-By Jill Lee,
ARS.
Danny E. Akin and W. Herbert Morrison are in the
USDA-ARS Quality Assessment Research Unit, Richard B.
Russell Agricultural Research Center, 905 College Station
Road, Athens, GA 30605; phone (706) 546-3482, fax (706)
546-3607, e-mail deakin@athens.net
hrhr06a@prodigy.com *


Earlier Castration Reduces
Stress

The kindest cut may be the one made at a young age,
when it comes to castrating beef cattle.
Scientists in the ARS Livestock Behavior Research
Unit at West Lafayette, Indiana, found calves castrated
shortly after birth suffered less stress and recovered faster
than those castrated around weaning time.
Farmers remove their calves' testicles to reduce
aggressiveness in male animals as they mature. It may
also improve the taste and texture of beef, says Julie
Morrow-Tesch, an ARS animal physiologist/ethologist
who heads the research unit. Meat from uncastrated cattle
can be tougher and may carry an unpleasant odor.
The West Lafayette lab studies livestock behavior in
order to gauge the stress level in animals.
"It's important to understand which management
practices can be combined or should be performed
independently to reduce stress in livestock," says
Morrow-Tesch. "By integrating castration prior to wean-
ing, stress levels may be lower for calves at weaning,
thereby improving animal well-being."
Morrow-Tesch used two different methods of castra-
tion-surgical and banding-on three separate groups of
Angus, Simmental, and crossbred calves: Two groups
were castrated and one was not. In banding, a tight rubber
band around the animal's scrotum cuts off the blood
supply to the testicles. After several days, the scrotum
drops off. Cattle producers prefer this method because it's
less expensive and not as labor-intensive as surgically
removing the testicles.
Calves are usually weaned when they're 36 weeks old.
The West Lafayette researchers castrated one group of
animals at 36 weeks and the other at 33, which was 3
weeks before weaning. They measured the calves' stress
level by checking blood levels of haptaglobin, a protein
the liver makes when an animal is injured.
They found that haptaglobin levels were higher in
calves castrated at 36 weeks than those castrated at 33
weeks or at birth-indicating a higher level of stress for
the older animals. Surgically castrated calves also showed
higher levels of haptaglobin, meaning surgical castration
was more stressful than banding.-By Dawn Lyons-
Johnson, ARS.
Julie Morrow-Tesch is in the USDA-ARS Livestock
Behavior Research Unit, Poultry Science Bldg., Room
218, Purdue University, West Lafayette, IN 47907;
telephone (765) 494-8022, fax (765) 496-1993, e-mail
jmorrow@www.ansc.purdue.edu *


Agricultural Research/August 1998



















Hygienic worker bees have uncapped some
of the cells in this brood comb and already
cleaned out chalkbrood mummies from
several of them. Mummies still awaiting
removal appear as white dots.


Variations in color among chalkbrood
mummies reflect the presence or absence of
fungal fruiting bodies-one of the
reproductive stages of the fungus.


Microbes Help Bees Battle

Chalkbrood


helpful microbes that live in
the hives, stored food, and
bodies of healthy honey
bees enhance many aspects of bee
life. Some of the microorganisms
produce antibiotics that might hold
the key to protecting tomorrow's
domesticated honey bees from one of
their worst enemies-the harmful
Ascosphaera apis fungus that causes
chalkbrood disease.
"A natural organism that's already
known to occur in hives of healthy
honey bees," says Agricultural
Research Service microbiologist
Martha A. Gilliam, "should be easier
than a synthetic chemical to register
with the federal government as a
biological control for chalkbrood."
Gilliam is with the ARS Carl Hayden
Bee Research Center in Tucson,
Arizona.
A microbe-based commercial
fungicide might be more effective at
penetrating the many layers that
protect chalkbrood spores.
"The spores themselves are
extremely thick-walled," says
Gilliam. "And they're enclosed
within three other protective struc-
tures-a sac that houses numerous
spores, a spore ball that holds many


sacs, and a spore cyst that contains
spore balls. Though not impenetrable,
these spore cysts are quite difficult
for a synthetic chemical to attack."
In her search for beneficial bacte-
ria, yeasts, and molds of the bee
world, Gilliam has combed hives of
the familiar European honey bee,
Apis mellifera, in the United States
and abroad. Her sleuthing has yielded
some 8,000 strains of microbes that
she has painstakingly isolated and
identified.
Gilliam's research has shown that
some of the microbes live amiably in
bees' intestines and help with diges-
tion. Others cause pollen grains-
carefully packed into the comb cells
by worker bees-to ferment and form
beebread that nourishes the colony's
brood and young bees. Some mi-
crobes act as food preservatives and
keep the beebread from spoiling in
the hive.
And Gilliam's investigations have
revealed that microbes such as certain
Penicillium, Aspergillus, and Bacillus
organisms apparently produce
compounds that inhibit growth of
chalkbrood-causing fungal spores.


A Growing Menace
Chalkbrood attacks only at the
larval stage. Bees develop from eggs
about the size of a pinhead that are
laid in a six-sided brood-comb cell
by the queen bee. White, wormlike
larvae hatch from the eggs and
transform into pupae. Later, young
bees emerge from the pupal cocoons.
Larvae may become infected with
spores carried in pollen or spread by
the nurse worker bees that tend the
colony's brood. Larvae mummified
by chalkbrood often look like tiny
sticks of chalk. Mummies may be
white, black, or greyish and mottled.
Since the 1970s, chalkbrood has
increased in spread and severity in
America. There are no chemicals
registered in the United States for its
control.
To fight chalkbrood, beekeepers
can frequently re-queen their hives;
that is, replace the reigning queen
with a new one. Other tactics include
discarding infected brood combs,
keeping hives well-ventilated, and
feeding sugar syrup and fresh pollen
to keep bees well-nourished, strong,
and healthy. Growers should also
remove dead mummies that are
dumped by nurse worker bees onto


Agricultural Research/August 1998


















iB
The entr
have bee











the bottom boards of the hive or the
ground near the hive.
Chalkbrood damage can affect the
pocketbooks of not only beekeepers
and growers, but also consumers.
Bees are important pollinators of
crops ranging from apples to zuc-
chini that are worth more than $10
billion annually in America. An
estimated 80 percent of all the food
that we eat-or, four out of every
five bites-comes from fruits and
vegetables pollinated by bees or
other insects.
Too, bees produce delicious
honey and fragrant beeswax.
Gilliam stores about 1,000
powdered, freeze-dried microbial
strains from bee hives in her Tucson
lab. When she needs certain cultures
for experiments, she revives them by
placing the powder on a gel-like bed
of nutrients or mixing them with a
nutrient broth.
In some tests of the microbes, she
uses European honey bees bred for
sensitivity to the chalkbrood fungus.
Stephen Taber III, now retired from
the Tucson lab, bred these bees for
the tests.
Gilliam feeds chalkbrood-tainted
"pollen patties" to the bees. Any
microbes that assist these super-


ance to this beehive is littered with chalkbrood mummies that
n expelled from the hive by hygienic worker bees.


vulnerable bees may be equally
useful-if not more so-to European
honey bees elsewhere. Her tests
include isolates of Mucor spinosus,
Rhizopus arrhizus, an as-yet-
unidentified Rhizopus, a Penicillium,
and Aspergillus tamarii.

Help From the Bees' Genes
Besides aid from microbial allies,
some worker bees get help from
another source: their genes.
Some bees have genes that compel
them to take on the chore of dispos-
ing of dead and dying brood. This
limits spread of A. apis spores, as
well as the microbes that cause other
diseases, such as American and
European foulbrood.
Scientists elsewhere have shown
that two different genes contribute to
this good housekeeping. One drives
the bees to remove the little beeswax
plug that seals each brood-comb cell.
A second gene directs the bees to pull
the sick or dead young out of the cell
and push them from the nest.
In earlier work, Gilliam and Taber
developed a quick, reliable test for
accurately detecting these inherited
traits. The test also produced more
evidence that bees can be selected
and bred for this healthful behavior.


For the test, researchers freeze a
chunk of brood-containing comb,
killing the immature bees, and they
place it in the hive. Hygienic bees
remove the dead within 48 hours.
Sloppy bees take a week or more.
Gilliam has used the test to identify
dozens of chalkbrood-savvy queens
from Arizona hives.
Many bee researchers agree that
genetically controlled hygiene habits
are the most important factors in
chalkbrood resistance or tolerance;
microbes play a secondary role.
However, Gilliam's research may
pinpoint strains of beneficial microbes
that can be commercially produced to
augment natural populations. These
microorganisms may become nearly
as important a tool as genetics for
boosting bee health.-By Marcia
Wood, ARS.
Martha A. Gilliam is at the USDA-
ARS Carl Hayden Bee Research Cen-
ter, 2000 E. Allen Rd., Tucson, AZ
85719; phone (520) 670-6380, ext.
121, fax (520) 670-6493.
Visit the Carl Hayden Bee Re-
search Center's home page on the
World Wide Web at http://
gears.tucson.ars.ag.gov *


Agricultural Research/August 1998













S ushi rice is sticky rice by
American notions of quality
texture. But stickiness is
what holds the raw fish and seaweed
together in that Japanese specialty.
More than half of American-grown
rice is exported, so it's important to
understand cultural differences when
it comes to developing this widely
used grain.
Scientists with the Agricultural Re-
search Service are using cutting-edge
technology and trained sensory panel-
ists to evaluate American K
rice varieties for Asian mar-
kets.
ARS chemist Franklin E.
Barton heads the Quality
Assessment Research Unit
at Athens, Georgia. He and
Elaine T. Champagne, who
is in charge of ARS' Food
Processing and Sensory
Quality Research Unit at
the Southern Regional
Research Center in New
Orleans, Louisiana, have
traveled to Japan several
times and found that con-
sumers' tastes in food differ
m A' i m Food sciel
from Americans' many separated
ways. scores for
"The Japanese palate can
detect subtle nuances in rice
quality that U.S. consumers
just can't perceive," Barton says.
"Here at home, most people cover
their rice with gravy. But in Japan,
the rice is almost an art form. The
food there has to be as beautiful to
look at as it is flavorful to eat."
During milling, U.S. rice proces-
sors remove the outer hull and by so
doing, for white rice, remove about
15 percent by weight of the grain's
outer layers. Japanese consumers like
whiter rice varieties and sometimes
mill their rice a little deeper.
"When I go to the store at home,"
Champagne says, "there're generally
one or two brands of medium- and


long-grain rice. In Japan, you find
rice connoisseurs who want variety
and prefer their rice fresh-milled
within days of purchase. In the Unit-
ed States, weeks or months may pass
from milling to market."
There is no one right way for rice
to taste. But the relative amounts of
protein and starch in rice play a big
role in its flavor and texture.
ARS scientists are using near-
infrared reflectance (NIR) technology
in studies to evaluate the chemical


ntist William Windham analyzes texture data for ric
into groups for light (L) or deep milling (D), based
partial least squares factors 1 and 2.


makeup of rice. They use other
instruments to check the physical
pressure needed to chew it. And the
scientists complement their research
with trained sensory panelists, be-
cause eating is an experience that
involves several senses simultan-
eously. Rice evaluation can't be
reduced to just a mechanical process.
So what do these machines-and
their human counterparts-actually
reveal? Americans like their rice to
cook firm, with kernels that break
apart easily; that happens when rice
is high in protein and amylose, or
rice starch. Japanese prefer a rice that


cooks soft and sticky-as when pro-
tein and amylose are low.

Getting Rice To Measure Up
What's needed is a way to evalu-
ate rice so the right variety goes to
the right consumer. By combining
human and mechanical evaluations,
researchers hope to find effective
tools for analysis.
"Japanese want a rice that is about
18 percent amylose, and they want 5
percent protein or less,"
says Barton. "American
rice ranges from 13 to 25
percent amylose and 5 to
9 percent protein. Our
rice is diverse enough to
offer the Japanese suit-
able varieties."
The NIR instrument
can determine the starch-
protein ratio in rice with
high precision by measur-
ing light just beyond the
visible spectrum.
When a rice sample is
exposed to a precisely
defined amount of near-
:e samples infrared light waves, a
on the computer measures the
reflectance-how much
light energy bounces
back. Each food compo-
nent has a characteristic reflectance.
To be effective, NIR equipment
has to be calibrated correctly. It
works based on many samples in its
database. When a new NIR reading is
taken, the computer compares the re-
sults only to the other evaluations al-
ready in its database.
"If you are trying to evaluate U.S.-
grown brown rice and all your previ-
ous samples are Japanese white rice,
you will get a bad reading," says
Barton. "But if you add a sufficient
number of brown rice samples, then
rice color won't confuse readings on
other unrelated characteristics, such
as amylopectin and amylose."


Agricultural Research/August 1998


































ARS chemist Franklin Barton uses a near-infrared reflectance (NIR) spectrometer to scan a
sample of rice for its starch-protein ratio, while the monitor in the background shows the
spectrum of the previous sample.


Barton demonstrated that any
correctly calibrated NIR system
could measure rice constituents and
would often give good marks to U.S.
rice. This prompted an international
re-evaluation of how rice quality is
determined.
If NIR technology could be cali-
brated for samples of every kind of
rice grown in the world, it might be
possible to have a global quality
evaluator for rice that could be sim-
ply calibrated for whatever market
was wanted-American high-protein,
Asian high-starch, or even Indian
aromatic.

A Global Taste Test
In working with Japanese scien-
tists and others, "one of our goals all
along has been to develop a universal
taste tester," says Champagne. "This
instrument would give an indication
of what sensory properties a rice has,
allowing you to find the most appro-
priate and highest value market for
that rice."


This universal taster is not yet per-
fected. But the work done in Athens
and New Orleans has already helped
Foss North America, Inc., an interna-
tional food evaluation company, to
develop a new international-style rice
taste-texture analyzer. It's being sold
throughout Australia, with more mar-
kets planned.
To make an NIR system mimic the
sensory evaluation of a person, it is
necessary to first start with what hu-
mans experience when eating a food
like rice.
That's where Athens food scientists
Bob Windham and Brenda G. Lyon
played a vital role. They joined forces
with Champagne and her colleague,
Karen L. Bett, to do the human taste
and texture evaluations and apply
them to NIR.
Lyon and Bett are experts at taste
and texture panels. But their task was
a big one. The first experiment in-
volved examining the effects of dry-
ing conditions, moisture content, and
degree of milling on four short- and


DiseaSe-Res.ot"i_..i-s -
Jeffersotn a rew semidfwarf:ri% e
variety, hit the market only last year
but is already popular-i.uug south
ern farmers who must contend with
fungus-caused rice diseases-such as
leaf blast and sheaf blight.
For an encore, ARS scientists who
developed Jefferson have just re-
leased another new rice variety-
Madison, which has multiple disease
resistance, like Jefferson, but matures
9 days later in the season.
Madison is ready for harvest about
120 days after seedlings emerge.
That's similar to other leading com-
mercial varieties, says ARS geneticist
Anna M. McClung, who heads rice
research at Beaumont. Texas.
Because early-planted Jefferson
and Madison mature by mid- or late
July. farmers may produce a second
harvest from the ratoon crop-new
growth sprouting from the flooded
stubble. Ratoon yields-can-be-a thii-d
to half the main crop about 60 days
after the first harvest.
Commercial seed companies can
obtain foundationiMadisonwseed
through theTexas Rice3 improvement
Association. More than 270,000
pounds of Jefferson, worth over
$200,000, were sold to seedsmen for
planting in the 1997 and 1998 grow-
ing seasons. This year. an-estimated
75.000 of the 270,000 acres of rice in
Texas were planted t.oJefferson.
In Uniform Ride Regional Nursery
tests, Madison, produced liog-grain
rice with July.crop yields similar to
Jefferson. Its milling quality was
found to be similar to-Jefferson, Cy-:
press, and-.Gilfmont. varieties. ARS
released XMadison jointly with state -
agricultural- experiment stations in
Mississippi, Arkansas,:Louisi~ a, -and
Texas.-B Ben. Hrdin, ARS,
Anna M. McClung isis: he =USDA-
ARS Rice Research: Unit,-: 109 Imes
Rd., Beaumini, TX 77713; phone
(409)- 752-5221, fax (409). 752-5720,
e-mail a-mcclungCgtwinu;4tu- .: :
--, "-:"--:: .5 : ";i -: "


Agricultural Research/August 1998










Comparison of Rice Varieties


medium-grain rice varieties grown in
the United States.
Samples of each of the four
varieties were obtained from four
rice-growing states-Arkansas,
Louisiana, Texas, and California. The
scientists looked at the effects of five
kinds of drying methods, two mois-
ture levels, and two kinds of milling
on each variety, evaluating a total of
220 samples: 110 for texture and 110
for flavor.
And that's how they split up the
work: Bett did flavor; Lyon did tex-
ture. The two scientists each led a
team of eight trained panelists in
sampling the rice. The panelists had
to have naturally sensitive palates.
But why so many samples? Be-
cause Americans and Japanese pro-
cess rice differently, U.S. rice pro-
ducers usually give their customers
12 percent moisture, while Japanese
growers go with about 15 percent.
Most U.S. producers dry their rice
mechanically, but some Japanese


KEITH WELLER (K8132-1)


Food scientist Brenda Lyon uses a
computerized texture analyzer that
translates compression analysis data for
rice samples into force compression curves
shown on the monitor. Correlation of these
values with NIR spectra will lead to
development of quality models for rice.


growers air-dry their rice right in the
field.
Because the Japanese palate is
more sensitive to rice flavor than that
of most U.S. consumers, Bett's group
faced the special challenge of finding
objective new ways to describe the
properties of cooked rice based on
flavor intensity, odor, and mouth
feel.
Some rice, for example, confers a
buttery smell and sweet, cornlike fla-
vor that the researchers aptly de-
scribe as popcorn. Other samples
bring to mind the pleasing scent of
dried lilac or lavender, and are thus
described as floral. A pungent, sulfu-
rous smell earned other samples the


less complimentary moniker of "sew-
er animal."
Not surprisingly, "Our panelists
learned that rice doesn't just taste
like rice," says Champagne. Then
Bett went on to do another flavor and
texture project using her panelists to
evaluate more than 100 different
kinds of rice from around the world.
After the panelists did their job,
Windham's expertise came into play.
His skill in mathematics and comput-
er science allowed him to "train" the
NIR systems in evaluating quality
based on the human data.
After Bett's and Lyon's panelists
rated texture and flavor characteris-
tics by numbers-ranging from 1 for


Agricultural Research/August 1998













not sticky to 10 for glutenous or glu-
ey-Windham had to turn the rank-
ings into equations the NIR computer
could understand.
Windham and Lyon had worked on
applying panel data to NIR systems
before, in a study of fresh and frozen
poultry. However, the rice project was
much more extensive, and flavor and
texture data with many subtle differ-
ences had to be uncovered.
"You can never replace human
taste evaluation, but near-infrared can
be a complement," said Windham.
"The trick is linking descriptive sense
to NIR's world of numbers and
calculations."

Getting to the Root of Differences
Evaluating the rice wasn't enough,
either. Researchers also needed to
understand why different flavor and
textures occur. The answer lay only
partly in the complex interaction of
protein, moisture, and amylose, says
Champagne.
Another mystery: Japanese con-
sumers tend to prefer short grains over
long. Short varieties tend to be low in
amylose, and long grains are usually
high. Barton's theory is that compo-
nents, such as starch and protein, in
short and long grains may also be
bound together differently.
Too, outside factors can play a sig-
nificant role in sensory qualities. Over
the past few years, ARS and other
food scientists have gained new in-
sight into subtle ways that mechanical
harvesting, milling, and other practic-
es can alter cooking properties of rice.
Lyon confirmed previous findings
that texture could be affected by
whether a particular rice is grown in
Arkansas or California. Japanese
consumers are known to prefer
California-grown varieties.
Deep milling-that is, removing
more than 15 percent of the grain's
outer layers-can increase stickiness,


but it's an expensive option for
producers.
Making rice fit Asian markets is
vital to U.S. growers.
The opportunity to reach the Jap-
anese market opened under the 1994
General Agreement on Tariffs and
Trade. For the first time, the United
States could export rice to Japan.
Since that market opened, research-
ers at ARS' National Rice Germ-
plasm Evaluation and Enhancement
Center at Stuttgart, Arkansas, have
collected germplasm of Japanese va-
rieties to evaluate for U.S. growers.
"Genetic engineering lets us make
breeding changes sooner, based on
consumer tastes," Lyon says. "It's
important that we give growers the
yields they need, but we also need to
think of our customers when we ex-
port to Japan."
This new open market may also
change Americans' tastes in rice. A
building appetite for ethnic cuisine
in this country is sparking more in-


terest in exotic rice, such as aromatic
varieties from abroad. American
growers are developing new hybrids
that combine high yields with these
popular exotic traits.-By Jill Lee,
ARS.
Franklin E. Barton, Brenda G.
Lyon, and William R. Windham are
in the USDA-ARS Quality Assessment
Research Unit, Richard B. Russell
Agricultural Research Center, 950
College Station Rd., Athens, GA
30605; phone (706) 546-3288, fax
(706) 546-3607, e-mail
wbarton @ athens. net
bglyon @ athens.net
bobw @ athens.net
Elaine T. Champagne and Karen
L. Bett are in the USDA-ARS Food
and Feed Quality Research Unit,
Southern Regional Research Center,
1100 Robert E. Lee Blvd., New
Orleans, LA 70179; phone (504) 286-
4451, fax (504) 286-4430, e-mail
etchamp @ nola. srrc. usda. gov
kbett@nola.srrc.usda.gov *


KEITH WELLER (K8131-1)


A nuclear magneuc resonance spectrumeter enauies cnemiis ranaKn Dariun krigint, irary
Gamble (center), and David Himmelsbach to graphically display a rice sample's water
absorption and gelatinization data.


Agricultural Research/August 1998













I t's December 1991, and the scene
is a darkened physics lab at New
Mexico State University at Las
Cruces.
U.S. Army atmospheric scientist Ron
Pinnick fires laser bursts at the target-
a sheep manure pellet mounted on a
pin. Within seconds, a computer screen
reveals the pellet's contents.
Pinnick's account of the test to his
friend Dean M. Anderson, an animal
researcher, caused a light to go on in Anderson's brain:
The laser had possibilities for analyzing livestock diets
through fecal analysis, he thought.
Anderson has conducted rangeland research for 21
years at the Jornada Experimental Range operated near
Las Cruces by USDA's Agri- DEAN ANDERSON (K81461)
cultural Research Service. .... :
Anderson's research has ::.'-1:. i.i
included monitoring food
preferences of grazing
livestock. And for most of his
time at the Jornada, this has
required him to analyze
animals' fecal material the
old-fashioned way: by hand.
"Collecting, preparing, and
examining samples under a
microscope requires several
days," Anderson says. "But
the laser takes only a few
seconds and is more precise Cattle and sheep forage oi
than the human eye." Short
bursts of laser light excite the
electrons in the sample and


6,500

c-
a)
c-
Z
0
2400

200
<1


Tarbush


400 500
Fluorescence (nm)


I


aria


cause a unique pattern of light
wavelengths to show up on a com-
puter screen as sort of light finger-
prints.
Linking a manure pellet's laser
fingerprints to chemical compounds
found in specific range plants,
Anderson says, could reveal exactly
what plants an animal has eaten.
And with this kind of dietary knowl-
edge, researchers can recommend
how ranchers might better match their animals to their land.
For example, if sheep crave a certain plant that goats won't
eat, it may make sense to recommend grazing sheep on land
with that plant.
He also envisions using the laser analysis system to help
spot individual animals with
L peculiar grazing tastes.
... Recently, Anderson
teamed up with scientists at
Sandia National Laboratory
in Albuquerque, New Mexi-
co. These scientists have
been evaluating use of alter-
native light sources that are
more readily available and
less destructive than lasers,
such as xenon lamps. They
are testing these for potential
civilian and military applica-
tions, including detection of
New Mexico rangeland. volatile organic, bacteria,
and transmissible spongiform
encephalopathies such as
mad cow disease.


Agricultural Research/August 1998


To obtain 3-D spectral signatures of
different arid rangeland plants,
scientists suspend ground samples in a
solvent. Electrons in molecules extracted
b) the solvent are excited bh
wavelengths of energy berteen 200 and
400 nanometers (nm I emitted b) a
xenon lamp. When the light is turned
off, energy characteristic o colors in the
visible light spectrum is released as
fluorescence. Such information will be
useful in performing fecal analysis to
determine the diet of foraging animals.












One Sunday in November 1991,
Pinnick-then working at the nearby
White Sands Missile Range-
accompanied Anderson for an
afternoon on the Jornada. Anderson
showed him his traditional technique
for collecting and analyzing fecal
pellets. The next month, they began
firing lasers at sheep pellets.
Since then, Anderson has ana-
lyzed more than 100 samples of
rangeland plants and animal manure.
He and his physics colleagues have
found the light fingerprints of many
plants including alfalfa, native
tobosa grass hay, and a shrub called
tarbush.
A colleague at Los Alamos
National Laboratory is interested in
the potential to monitor the diets of
wild deer and elk that graze on
federal land. Wild animal diet
analysis is important to developing
wildlife management strategies.
Anderson's basic technique is
simple. He uses chloroform or a
saline solution as a solvent to extract
samples of plants and manure. Then,
in a darkroom, the laser or xenon
beam is aimed at the sample. Both
the laser and the xenon lamp are
connected to electronic equipment
for capturing and analyzing light
fingerprints.
"We would like to evaluate about
500 rangeland plant species found
on the Jornada, starting with the 25
or 30 most popular with our live-
stock," he says. "We also need to
evaluate results in different seasons
and with other solvents."-By Don
Comis, ARS.
Dean M. Anderson is at the
USDA-ARS Jornada Experimental
Range, P.O. Box 30003, MSC 3JER,
New Mexico State University, Las
Cruces, NM 88003-8003; phone
(505) 646-5190, fax (505) 646-5889,
e-mail deanders@nmsu.edu *


Microwaves To Measure Fruit Maturity

Microwave ovens deserve their reputation for making food preparation
easier and faster. But in the future, microwave technology may play a taste-
tester role that could mean fresh fruits and vegetables arrive at the table with
even more fresh, just-picked flavor.
The microwaves used in this research were at a very low level. The goal
wasn't to cook the fruits and vegetables but to measure the properties that
influence how electromagnetic waves pass through them.
Two of these properties are well known to physicists and electrical engi-
neers but may be new to others. The dielectric constant tells how a material,
living or not, stores electric energy. The dielectric loss factor indicates the
ability of a material to absorb energy from an electric field and convert it to
heat. As it turns out, there is a correlation between these dielectric properties
and the maturity of fresh produce.
"We characterized produce from a microwave viewpoint," says Agricultural
Research Service's Stuart Nelson. "We did this to build a database and explore
its use as a measure of maturity in peaches."
Nelson, an agricultural engineer, and Roy Forbus, an industrial engineer
who is now retired, measured dielectric properties on 23 fruits and vegetables
for their database. The scientists got their samples at the same place consum-
ers usually find theirs: the supermarket produce section.
Once they had a database with information about the dielectric properties of
fruits and vegetables in general, Nelson and Forbus were ready for a subse-
quent project. They would look at microwaves as a tool for evaluating ripeness
in peaches. This time, the University of Georgia's Agricultural Experiment
Station made peaches available to test-Forbus and a student did the picking.
Why look at microwaves as an evaluating tool? They may detect total
soluble solids, which are really sugars, in fruits such as peaches. Sugars
increase with ripeness. Not enough sugars means your peach was probably
taken too soon from the tree.
Preliminary results suggest low-level microwave measurements may lead to
development of instruments that growers could use to pinpoint ideal harvest-
ing times. Dielectric properties varied with microwave frequency and the
character of the produce itself, such as the fruit's chemical composition and
the amount of water in it.
A bonus of this research is that the information could help processors of
microwave foods keep the fruit compote in your TV dinner more flavorful
during that fast-track heating.-By Jill Lee, ARS.
Stuart O. Nelson is in the USDA-ARS Quality Assessment Research Unit,
Richard B. Russell Agricultural Research Center, P.O. Box 5677, Athens, GA
30605-5677; phone (706) 546-3101, fax (706) 546-3607, e-mail
sonelson@bac.uga.edu *


Agricultural Research/August 1998








Old Virus Morphs Into New

Chicken Threat


I n the past 2 years, a new strain
of avian leukosis virus has
swept like wildfire through the
broiler breeder chicken industry
around the world. It has attacked the
industry at its source, decimating the
breeder birds that are the parents of
the birds we eat.
Gregorio Rosales, president of the
U.S. Primary Breeders Veterinary
Roundtable, says losses of breeder
birds can be as high as 20 to 40
percent in the most severe cases. The
usual loss is 1 to 2 percent per week
during the phase when birds are at
their peak of laying the eggs that will
be raised as broilers.
The roundtable includes the top
seven U.S. primary breeders-that
account for 95 percent of the U.S.
broiler industry. Rosales, a veterinary
medical officer with Ross Breeders,
Inc., of Elkmont, Alabama, says
infections are now occurring in
younger chickens and spreading
faster than any other avian leukosis
virus (ALV) known before. This new


strain, referred to as ALV subgroup
J, was first isolated in England in
1989 and in the United States in
1994. Infections caused by this virus
reached epidemic proportions in
1996.
Shortages of breeding stock are
already showing up, according to
Rosales. He says this threatens the
industry's ability to meet the bur-
geoning demand for chicken on the
dinner table. U.S. industry managers,
for example, are concerned that they
may not be able to keep up with
consumer demand for almost 8
billion broilers a year. "The threat to
breeding companies is enormous,"
says Rosales.
"If a producer goes out of busi-
ness, a gene pool assembled over
many years of breeding is lost. And
this would be a serious loss, since
there are no more than eight major
breeding firms in the world," he says.
Murray R. Bakst, acting head of
the Agricultural Research Service'
Avian Disease and Oncology Labo-


Molecular biologist Robert Silva and technician Cecyl Fischer inspect DNA sequences of
samples from the most recent avian leukosis virus sub-group J isolated from a U.S. broiler
breeder flock.


"The threat to breeding
companies is enor-
mous. --Gregorio Rosales, presi-
dent of the U.S. Primary Breeders
Veterinary Roundtable


ratory located near the campus of
Michigan State University at East
Lansing, says the industry came to
that lab for help.
This makes sense, says veterinary
medical officer Richard L. Witter,
because the East Lansing lab was set
up in 1939 for a similar crisis-
involving less virulent strains of
avian leukosis. In the same spirit of
cooperation seen today, Michigan
State then donated 50 acres of land
for the lab.
Witter formerly headed the East
Lansing lab but has recently returned
to full-time research, spending some
of his time working with avian
leukosis.
Witter, who has followed the
disease for much of his career, says
that the virus that causes the often-
fatal tumors in chickens was first
isolated in the 1940s by Ben R.
Burmester at the East Lansing lab.
Subsequent research found that avian
leukosis is actually caused by a group
of viruses. Before 1989, five sub-
groups affecting chickens had been
identified, A through E.
"Until sub-group J," says Witter,
"the various strains of the virus
predominantly caused lymphoid
tumors that grow from cells in the
chicken's bursa, an organ near the
end of its intestinal tract. The new
strain causes predominantly myeloid
tumors, which grow throughout the
body, often on bone surfaces."
Witter says the breakthrough that
led to solving the earlier avian


Agricultural Research/August 1998












leukosis problem came in 1977 with
ARS' development-in concert with
industry-of a quick test. Over the
next 10 years, a detect-and-eradicate
strategy was put into action, and the
industry was on a secure path.
Until now.

New Measures Needed
Once found only in egg-laying
breeds, the disease has quietly
evolved into a new strain found only
in chickens raised for meat.
The ALV-J strain renders the
industry's detect-and-eradicate
strategy useless. It is also highly
variable, seeming to change con-
stantly, and it spreads too fast. By the
time it is detected and the infected
birds are removed, it has already
spread to other chickens.
"That's terrible for eradication,"
says Aly M. Fadly, the ARS veteri-
nary medical officer who heads the
ALV-J research team.
Unfortunately, Fadly says, team
members may have to unlearn what
they know about avian leukosis,
because the new strain is so different.
"It may require an entirely new
control technology," he says.
The J subgroup was first isolated
in 1989 by L.N. Payne (retired),
formerly with ARS' British counter-
part agency, the Institute for Animal
Health, located in Compton New-
bury, Berkshire, England.
Fadly identified the U.S. strain in
1994. Telephone calls from industry
convinced him by 1996 that the J


Built for White Leg-
horn egg-layers, the
lab's pens and cag-
es were too small to
hold broilers.


Agricultural Research/August 1998


strain was spreading far more rapidly
than other strains. He says a typical
call went like this: "Although we
removed all the hens infected with
ALV-J, we're still finding new ALV-
J cases in their penmates."
Earlier ALV strains were poor at
spreading by contact. Just removing
infected chickens solved the problem.
But the J strain spreads with deadly
efficiency from hen to hen and chick
to chick.
"We don't yet understand how it
moves so fast," Fadly says.
"Myeloid leukosis is probably the
biggest threat to the broiler industry
worldwide at the moment," says
Rosales.
"There is a tremendous need for
universities and federal programs to
continue working on it. The ARS lab
at East Lansing and Britain's Institute
for Animal Health have been leaders
in poultry tumor research," he says,
"particularly East Lansing. If it
weren't for their work, we wouldn't
have the industry we have today."


Fadly, who serves as adviser to the
Primary Breeders Veterinary Round-
table, says the J research team at East
Lansing is working with world-class
scientists. These include Kathleen
Conklin at the University of Minne-
sota at St. Paul, an expert on the
molecular biology of tumor-causing
viruses, and Hsing-Jien Kung, a
tumor expert at Case Western Uni-
versity in Cleveland, Ohio.
Both Conklin and Kung are
interested in learning how retro-
viruses such as the J virus cause
cancer. Conklin is also intrigued by
the variability of the J virus and its
ancient wildfowl genes.
Payne had found a switch point,
where two chains of genes from two
different strains of avian leukosis-
subgroup A from modern-day
wildfowl and an ancient subgroup
found in every chicken's genome, or
genetic library-recombined.
The J virus cannot infect people or
other animals besides chickens.
Retroviruses like J reverse the normal


BRUCE FRITZ (K8129-1)



4_ 3(


In one of the remodeled floor pens at the ARS Avian Disease and Oncology Laboratory in
East Lansing, Michigan, chemist Lucy Lee and technician Barry Coulson inoculate broiler
chickens with an experimental recombinant vaccine against ALV-J.













viral replication process of injecting
viral DNA into an infected cell to
reproduce viral RNA. When a
retrovirus infects a cell, it injects its
RNA into the cell, along with an
enzyme that uses the RNA template
to make a DNA viral molecule. The
retrovirus becomes part of the
infected animal's genetic makeup.
Hubbard Farms, Inc., of Walpole,
New Hampshire, is one of the
primary breeding companies repre-
sented in the roundtable firms. In a
cooperative research and develop-
ment agreement with this company,
ARS developed a DNA-based test for
detection of the virus, called a
polymerase chain reaction (PCR)
test. ARS expects to sign many more
such agreements with companies,
including a diagnostic lab, for work
on a quick detection test that can be
used in the field.
In 1997, the East Lansing lab
pulled out all the stops. By June, the
lab's leader received permission to
redirect $200,000 to J research. Six
of the unit's eight scientists spend at
least some of their time on this work.
Fadly has a growing number of
technical assistants, including two
technicians and two Michigan State
University graduate students. He is
also working with poultry experts in
the public and private sectors and is
collaborating with scientists at the
University of Georgia at Athens and
the University of Delaware at
Newark.
Recently, Fadly received 10
samples of J viruses found on
breeder farms. Team member Robert
F. Silva, a microbiologist, used the
PCR test to see how variable these
samples were. His tests gave the first
proof that they were as variable as
feared.
"They have changed greatly since
they were first detected in England in
1989," says Silva, "and everyone is


wondering what changes are yet to
come."
Solid evidence emerged once
Silva went on to map genes of key
parts of the virus samples. In com-
paring the new samples with each
other and with the strain found in


ARS veterinary medical officer and project
leader Aly M. Fadly and visiting Spanish
scientist Natalia Majo, an assistant
professor at the University of Barcelona,
examine microscopic lesions in tissue
samples from poultry with ALV-J infection.


England, he confirmed significant
genetic changes, including the loss of
stretches of DNA in one sample.
"Because of this extreme variabil-
ity, it will be difficult to develop
effective vaccines and diagnostic
tools," Silva says.
The discovery of sub-group J
caught the ARS unit, as well as the
industry and researchers everywhere,
off guard. For one thing, the chicken
pens at East Lansing had been built
for smaller White Leghorn egg-


layers, next to which broilers look
like turkeys. The lab's pens and
cages were too small for the broilers.
The veterinary roundtable gave
the East Lansing lab $140,000 for
poultry research. This freed up more
ARS funds, in addition to the
$200,000 in redirected funds, to buy
new cages and retrofit the lab and
chicken pens for broiler research.
The lab's maintenance staff worked
overtime and had the pens ready by
the end of 1997. The first broilers
arrived in January 1998.
ARS immunologist Henry D.
Hunt is exploring the idea of a quick
test that could spot the virus and lead
to removal on the same day a chick
hatches. He is taking blood samples
from broiler chicks to look for virus-
infected cells. He also wants to see if
he can use chicken cells to produce
ALV-J proteins for a possible
vaccine.
Meanwhile, ARS biochemist Lucy
F. Lee is working on developing a
genetically engineered vaccine.
"We're building an ever-expand-
ing consortium of private industry,
university, and federal researchers to
solve the problem," says Witter.-
By Don Comis, ARS.
Murray R. Bakst has returned to
the USDA-ARS Germplasm and
Gamete Physiology Laboratory,
Bldg. 262, 10300 Baltimore Ave.,
Beltsville, MD 20705-2350; phone
(301) 504-8795, fax (301) 504-8546,
e-mail murray@ggpl.arsusda.gov
Richard L. Witter, Aly M. Fadly,
Robert F. Silva, Henry D. Hunt, and
Lucy F. Lee are at the USDA-ARS
Avian Disease and Oncology Labo-
ratory, 3606 East Mt. Hope Rd., East
Lansing, MI 48823; phone (517)
337-6828, fax (517) 337-6776, e-
mail witterr@pilot.msu.edu
fadly@pilot.msu.edu
silvar@pilot.msu.edu
hunthd@pilot.msu.edu
leelu@pilot.msu.edu *


Agricultural Research/August 1998






-----I-mm-Wmm-


Sticks and Stones May Brake
Erosion
In silty southern streams, sticks and
stones-willow posts and limestone
rocks-can protect bluegill, bass, and
catfish from the effects of erosion
caused by watershed development.
More roads, roofs, and fields mean
more rainwater reaching streams more
quickly with greater erosive punch.
That's why ARS, the U.S. Army
Corps of Engineers, and USDA' s
Natural Resources Conservation
Service in 1994 developed a coopera-
tive project to restore stream and creek
habitats. As part of the effort, ARS
conducted a 3-year study to determine
which of the two stabilizing tech-
niques would be more effective in
restoring fish habitat in a stream
damaged by extreme erosion. The
limestone seemed slightly better,
based on diversity and number of fish,
but the willows are more economical.
The 7- to 20-foot dormant willow
posts, planted in the streambanks,
come to life in spring and grow sturdy
roots to protect the bank from erosion.
Piles of limestone rock-formed into
ridges perpendicular to the current or
parallel with the bank-deflect
currents and hold slumping banks in
place. F. Douglas Shields, Jr., USDA-
ARS National Sedimentation Labora-
tory, Oxford, Mississippi; phone (601)
232-2919, e-mail
shields @ sedlab.olemiss.edu


SCOTT BAUER (K5210-16)


29MC101o' -,,. -
Hydraulic engineer Doug Shields (right)
and student research assistant Rick
Rauteux observe changes in channel
geometry and stream corridor habitats
caused by water rushing over a headcut.

Agricultural Research/August 1998


Two Proteins Determine Wheat
Texture
ARS scientists have identified the
elusive molecular basis for wheat
texture, referred to as hardness or
softness. Generally, hard wheats are
for breads; soft wheats, for cookies
and cakes. The discovery should help
breeders develop super-soft and other
custom wheats. ARS researchers have
shown for the first time that two
proteins called puroindolines-pinA
and pinB-correlate perfectly with
wheat texture. All soft wheats have
pinA and a specific form of pinB that
has glycine as its 46th amino acid.
Most hard wheats differ from soft
wheat only in having serine as the
46th amino acid in pinB. The other
hard wheats tested have the glycine
pinB and no pinA at all. With tradi-
tional breeding or biotechnology,
scientists could develop varieties with
specific puroindoline combinations.
By boosting levels of soft-wheat
puroindolines, for example, they might
create a super-soft variety for making
new kinds of cakes and cookies.
That's because millers could grind the
grain more finely than is now possible
without damaging the starch, a com-
mon milling problem. Craig Morris,
USDA-ARS Western Wheat Quality
Laboratory, Pullman, Washington;
phone (509) 335-4055, e-mail
morrisc @ wsu.edu



Spud Book Holds 4,000 Pedigrees
A new compilation of more than
4,000 pedigrees of North American
and European potato varieties is
available for the first time to potato
breeders and industry. An ARS
geneticist compiled the handbook in
collaboration with scientists based in
Poland, the Netherlands, and Ireland.
The handbook gives information on a
variety's origin, year of release,
countries of cultivation, female and
male parents, source or list of refer-
ences, and unreleased ancestors of


currently cultivated varieties. Scientists
compiled the information from breed-
ers and institutions preparing parental
lines for breeding in the United States,
Europe, and Russia. In North America,
the pedigrees are computerized and
also published in the American Potato
Journal. European varieties, however,
are often released without publishing
pedigree information. The handbook
will be available in both English and
Polish. The United States ranks fourth
globally in potatoes, producing nearly
48 billion pounds a year. Kathleen G.
Haynes, USDA-ARS Vegetable Labora-
tory, Beltsville, Maryland; phone (301)
504-7405, e-mail
khaynes @ asrr.arsusda.gov



New Homegrown Hop Adds German
Zest to Beer
Brewers and beer drinkers can now
find the prized aromas of hops from
Germany's Tettnang region in ARS'
new variety, Santiam. Hops give beer
its distinctive aroma and a zesty
bitterness to balance the sweetness of
malted barley. While the original
Tettnanger variety can be grown in this
country, its yields are lower than in
Germany. Santiam, however, yields
twice as much as Tettnanger grown in
Oregon, Washington, and Idaho, the
principal hop-growing states. Hop
seeds can add undesired oils to beer,
but Santiam is the first naturally
seedless Tettnang-type hop. With
Santiam, ARS has now provided
domestic alternatives to all three
premier European aroma hops: Tett-
nanger, Hallertau, and Saaz. In 1997,
ARS hop varieties accounted for two-
thirds of the U.S. harvest valued at
$117 million. At least one-third of the
hops in American beers have ARS
origins. John Henning, USDA-ARS
Forage Seed Production Research
Center, Corvallis, Oregon; phone
(541) 750-8746, e-mail
jhenning @ css.orst.edu


amm m mmmmm 11 lm I I 1 11m1 1 ls





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