Group Title: Agricultural research (Washington, D.C.)
Title: Agricultural research
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Title: Agricultural research
Uniform Title: Agricultural research (Washington, D.C.)
Physical Description: v. : ill. ; 25-28 cm.
Language: English
Creator: United States -- Science and Education Administration
United States -- Agricultural Research Administration
United States -- Agricultural Research Service
Publisher: Science and Education Administration, U.S. Dept. of Agriculture :
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Supt. of Docs., U.S. G.P.O., distributor
Place of Publication: Washington D.C
Publication Date: August 1997
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Subject: Agriculture -- Periodicals   ( lcsh )
Agriculture -- Research -- Periodicals   ( lcsh )
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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: VID00009
Source Institution: University of Florida
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Resource Identifier: ltuf - ABP6986
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issn - 0002-161X

Full Text
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FORUM


Making More Crop-
land by Tinkering
With Plants
The heart of America's riches has
always been its land.
It was the promise of land that
lured many of the men and women
who settled this country, starting with
the 104 English who landed at James-
town, Virginia, in May 1607. As the
nation grew, its patterns of settlement
were shaped by the quality of the
land (and availability of water).
Anyone who's ever flown coast to
coast can hardly fail to marvel at the
vastness of the United States. As one
English bride remarked when she
first came to this country with her
American husband and flew from
New York to California, "After we'd
gone as far as Iowa, I simply couldn't
believe it."
In fact, the land mass that encom-
passes the 48 contiguous states totals
1.9 billion acres-but so does the Sa-
hara desert. The crucial element is the
quality of the land, not the quantity.
According to USDA statistics, the
United States-excluding Alaska--
has 423 million acres of cropland,
ranging from Class I land, which has
no significant limitations for crop
production, to Class IV, where crops
should be grown only under carefully
selected land management practices.
Another way to assess land quality
is to use the classification of "prime
farmland," defined as possessing the
growing season, moisture supply, and
soil quality needed to sustain high
crop yields when treated and man-
aged according to modern farming
methods. Our grand total of prime
farmland-232 million acres-is
barely more than I out of every 2
acres of U.S. cropland, again exclud-
ing Alaska.
As any gardener can tell you, suc-
cess in growing specific plants-like


real estate values-often comes down
to location, location, and location.
Agricultural producers must fre-
quently wrest their crops from land
plagued by poor drainage, limited
root zones, limited natural fertility,
poor water availability, or high ero-
sion potential, as well as by a poor
mix or outright shortage of soil nutri-
ents needed for plants to thrive.
Agricultural Research Service sci-
entists are well aware of these prob-
lems and have worked to develop
crop varieties and soil management
systems that can deliver economic
yields under less than ideal growing
conditions. ARS supports one of the
world's few laboratories dedicated
primarily to the study of that intricate
relationship between soil and plants,
the U.S. Plant, Soil, and Nutrition
Laboratory in Ithaca, New York.
In this issue of Agricultural Re-
search magazine, you'll read about
how ARS researchers in Ohio and
Georgia are developing soybean and
wheat plants that can grow under
flooded conditions and how they've
traced the secret of survival to the
plants' roots, strangely riddled with
air passages.
Other ARS researchers have also
tackled aspects of the dilemma of
growing crops in inhospitable set-
tings. Some of their findings:
At the Ithaca lab, scientists dis-
covered that plants may have a sensi-
tive spot at the tips of their roots
when it comes to exposure to alumi-
num. Aluminum toxicity is the pri-
mary problem limiting agricultural
production on acid soils, the type of
soil seen in about half of the world,
including the northeastern and south-
eastern United States, South Amer-
ica, and Africa. In laboratory tests,
when aluminum was applied to other
parts of the roots, the plants were
able to function normally. But when
aluminum was applied to plant root
tips, root growth was inhibited within


a matter of hours. The scientists say
excessive aluminum also interferes
with plants' ability to take up essen-
tial calcium from the soil.
Crops such as cotton and corn
might borrow genes that give extra
drought tolerance. When dried star
moss, Tortula ruralis, is given just a
few drops of water, it changes quick-
ly from a rusty brown mass to lush,
green individual branches with star-
like needles. ARS researchers in Lub-
bock, Texas, isolated 74 proteins
thought to be involved in the repair
process because they increased in
numbers within 2 hours after the
moss was moistened.
A group of special proteins that
corn plants produce at times of
drought or salty conditions could
hold the key to developing plants that
can better withstand such adverse
conditions. ARS laboratory studies in
Hawaii showed that when clusters of
corn cells were subjected to too much
salt or too little water, the cells manu-
factured three proteins not found in
other cells free of such stresses. Like-
wise, when corn seedlings were de-
prived of water, they reacted by mak-
ing two other proteins not produced
by their well-watered counterparts.
Those two quickly disappeared when
the tiny plants were watered.
Each of these discoveries is just
one small part of the gigantic puzzle
of soil-plant-environment interac-
tions. But with the world's popula-
tion expected to climb from its cur-
rent 5.8 billion to 10.4 billion by the
year 2100-and a limited base of ara-
ble land worldwide-every new bit
of information that helps us make the
most of our available agricultural
land could prove vital in the effort to
produce enough food in the years to
come.

Michael D. Jawson
ARS National Program Leader
for Soil Biology & Biochemistry


Agricultural Research/August 1997








August 1997
Vol. 45, No. 8
ISSN 0002-161X

Agricultural Research is published monthly by
the Agricultural Research Service. U.S.
Department of Agriculture, Washington, DC
20250-0301.
The Secretary of Agriculture has determined
that this periodical is necessary in the transac-
tion of public business required by law.
Dan Glickman, Secretary
U.S. Department of Agriculture
Catherine Wotekj, Acting Under Secretary
Research, Education, and Economics
Edward B. Knipling, Acting Administrator
Agricultural Research Service
Sandy Miller Hays, Acting Director
Information Staff
Editor: Lloyd McLaughlin (301) 344-2514
Assoc. Editor: Linda McElreath (301) 344-2536
Art Director: William Johnson (301) 344-2561
Photo Editor: John Kucharski (301) 344-2900
Assoc. Photo Ed.: Anita Daniels (301) 344-2956
Information in this magazine ij public property
and may be reprinted without permission. Non-
copyrighted photos are available to mass media
in color transparencies. Order by photo number
and date of magazine issue.
Subscription requests should be placed with
New Orders, Superintendent of Documents,
P.O. Box 371954, Pittsburgh. PA 15250-7954.
See back cover for order form.
Complimentary 1-year subscriptions are
available to public libraries, schools, employees
of the U.S. Department of Agriculture, and the
news media. Send requests or comments to:
Editor, Agricultural Research Magazine, Room
408, 6303 Ivy Lane, Greenbelt, MD 20770. E-
mail lmclaugh@asrr.arsusda.gov
To visit Agricultural Research magazine on the
Internet, go to www.ars.usda.gov and select
News and Information.
This magazine maN report research involving
pesticides. It does not contain recommendations
for their use, nor does it imply that uses dis-
cussed herein have been registered. All uses of
pesticides must be registered by appropriate
state and/or federal agencies before they can be
recommended.
Reference to any commercial product or service
is mide with the understanding that no discrimi-
nation is intended and no endorsement by the
U.S Department of Agnriculture is implied.
USDA prohibit, discnminalion in its programs
on the basis of race, color, national origin, sex,
religion, age, disability, political beliefs, and
marital or familial status. (Not all prohibited
bases apply to all programs.) Persons with
disabilities who require alternative means for
communication of program information
r Braille. large print, audiotape, etc.i should
contact USDA's TARGET Center at (2021 720-
2600 n oice and TDDi. To file a complaint.
%rite the Secretary of Agncullure. U.S.
Department of Agriculture. "A ashington. DC
20250. or call 1800) 245-6340 (oice.I or (2021
720-1127 (TDD) USDA ii an equal opportu-
nity employer.


Agricultural Research



AERENCHYMA-For Crop Survivability 4

Mouth-Watering New Fruits 9

Less Fire, More Science for Grass Growers 12

Boosting Ellagic Acid in Strawberries 16

Smoking Out Bee Mites 19

Fungal Rivalry Protects Tomatoes 20

Enzyme Catalyst for Solventless Extractions 22

Winter Wheat Gets New Resistance to Hessian Fly 22

Science Update 23


















Cover: A corn-eastern
gamagrass hybrid.
Eastern gamagrass is a
native grass with a gene
pool that has a lot to offer
corn, including resistance
to cold and insects, as
well as tolerance to
drought and flood. Photo
by Scott Bauer. (K7698-1)


Agricultural Research/August 1997








AERENCHYMA
Lifelines for Living Underwater


It all started with the "Great Dig
of 1995" on the Spaulding farm
in Missouri. In September of that
year, a group of scientists from
around the country had gathered near
a soybean field.
A backhoe had dug a trench 7 feet
deep by 3 feet wide at the edge of a
50-year-old patch of eastern gam-
agrass that extended into the soybean
field. The scientists sought the secret
of a grass that farmers reported had
thrived during droughts-as well as
during prolonged flooding in 1993.
The first clue they got was that the
roots reached down to at least 7 feet,
easily passing through a clay layer
that is impenetrable to most crop
roots. And the roots of nearby
soybeans seemed to go down deeper
than the usual 2 feet, possibly be-
cause they were able to use the
channels formed by previous eastern
gamagrass roots.
The ability to penetrate the clay
layer and explore deeper regions for
soil water was one reason the grass
could stay "green and nice when
everything else was brown," says


Richard W. Zobel. He is a plant
geneticist with the Agricultural
Research Service's U.S. Plant, Soil,
and Nutrition Laboratory at Ithaca,
New York.
Zobel squeezed some of the thick
roots and found them squishy,
something he had never seen in roots
as healthy as these. But then Zobel
had never felt the roots of eastern
gamagrass.
One of this country's original
prairie grasses that helped feed roving
herds of bison, its population has
declined under continuous grazing to
where it isn't even known to many
experts-let alone the general public.
But what Zobel would find when he
put those roots under his microscope
in his motel room later that evening
would put eastern gamagrass on the
road to becoming a household
word-along with "aerenchyma."
That evening, Zobel excited his
colleagues in the motel restaurant
with his announcement that he had
found aerenchyma in all the roots.
Aerenchyma [pronounced air-
ENK-a-ma], even less familiar to


many than eastern gamagras,. is
tissue with air passages that enable
roots of plants-rice. for example-
to grow under after. In aquatic
plants, the corky tissue aids gas
exchange and buo\ anct.
Instead of a root tightly( packed
with an organized arra\ of cells, roots
with aerench3 ma are sponge. ith
large holes formed b\ cells either
pulling apart or disintegrating. These
holes run longitudinalkN through the
roots. The\ enable flooded roots to
snorkel air from the abo\ water parts
of the plant.
W. Doral Kemper-former ARS
national program leader for soil
management. \\lio is now retired-
participated in the digging expedition
organized by colleague E. Eugene
Alberts at Columbia. Missouri. He
explains that aerenchyma tissue
enables roots to sur\ i\e and punch
through the claypan layer \ hen it's
sopping wet, the only time it" soft
enough to be penetrated.
"'These roots live less than 2
years." Kemper says. '"But when they
die, they decompose slowly and help


At the USDA Natural Resources
Conservation Sernice's Big Flats (Nemw
York) Plant Materials Center, scientists
are excavating eastern gamagrass roots for
study. Left to right: agronomist Paul
Salon, NRCS; technician Richard Lychalk,
ARS; research scientist Jason Bull, Bureau
of Sugar Experiment Station, Queensland,
Australia: and plant geneticist Rich Zobel,
ARS.


Agncultural ReseMa lrh/ALIUtuL 19)9'













hold channels open for new genera-
tions ot roots. providing the gam-
agrass w ith continued access to water
in and below the claypan."
This additional water reser% oir
enables the plants to continue grow-
ing during prolonged droughts.
That's one of the reasons the
aerenchyma study excites Kemper as
no other field of research has in his
extensive career. "It promises to
relieve negative effects of both
drought and flooding, which are the
primary restraints to sustained
production in soils with restrictive
layers," Kemper says.

Plants As Rototillers
Alberts, who leads the ARS
Cropping Systems and Water Quality
Research Unit, says that part of the
promise of aerenchyma-gifted plants
like eastern gamagrass is using plant
roots instead of machines or chemi-
cals to improve a field.
"Tillage machines can help break
up the clay layer," says Alberts, "but
the claypan quickly returns. The only
tools likely to permanently improve


these dense soil layers in the long run
are plant roots. They can literally be
biological tillers, improving water
movement and providing channels
for other roots."

Not Just in Gamagrass
Zobel has also discovered aeren-
chyma in Vetiver grass, a plant that
farmers in India use in grass hedges
to collect soil and build terraces
similar to those built here with
bulldozers. He has also found some
short, upright types of eastern
gamagrass that would be good
candidates for grass hedges.
Excited by the potential of aer-
enchyma to enable crops to thrive in
wet soils and soils with restrictive
layers, John W. Radin, ARS national
program leader for plant physiology,
helped Alberts, Zobel, and Kemper
organize a workshop in Atlanta last
year. They invited all ARS scientists
known to be working on aerenchyma.
One of the workshop participants,
plant physiologist Tara T. VanToai,
has soybean plants growing partly
underwater in plots in Columbus,


Ohio. Another. soil scientist James E.
Box, Jr., is de\ eloping similarly
flood-tolerant wheat varieties in
Watkinsville. Georgia. w while others
in Florida are searching for \%ayN to
make sugarcane flood tolerant.
The Great Dig at the Spaulding
farm led to the realization that the
common thread \\as aerenchyma, a
trait normal asociated \ ith aquatic
plants. And, it %as suggested, since
eastern gamagras is a relative of
corn. the trait might be transferred to
that crop.
"Apparently it is possible," says
Bryan K. Kindiger, who is a plant
geneticist at the ARS Southern Plains
Research Station at Woodward,
Oklahoma. "We've done it. uninten-
tionally," he says. "We've already\
crossed corn and gamagrass and
generated hybrids that reproduce by
apomixis, which is asexually, through
seed." (See "Apomixis; It Could
Revolutionize Plant Breeding."
Agricultural Research, April 1993,
pp. 18-20.)
"Apomixis allows corn to repro-
duce seed clonally, causing seed to


Air-filled passages in roots allow them to grow

in saturated soil, penetrate compacted layers,

and tolerate both droughts and floods!


Agricultural Research/August 1997













breed true from year to year and en-
abling farmers to maintain high-
yielding varieties indefinitely," says
Kindiger. "By luck, we found the aer-
enchyma trait to be strongly associat-
ed with the same chromosome that
carries the gene for apomixis."
Farmers have long dreamed of
breeding apomixis into all major
crops, says Kindiger. The location of
the genes now promises to give them
not only this goal, but drought and
flood tolerance as a bonus.
"Science has caught up with the
dream," says Kindiger. He and
colleagues have introduced aerench-
yma into corn by crossing it with
teosinte, a large fodder grass that is a
close relative of corn.
"Our research emphasis is on
improving gamagrass as a grazing
crop for cattle," says Kindiger,
"especially in making gamagrass
reproduce asexually.
"I hadn't heard of aerenchyma
until last year, but the aerenchyma


angle represents a good spin-off to
our apomixis research."
Kindiger says eastern gamagrass is
a wild grass with a gene pool that has
a lot to offer corn, including resis-
tance to cold and insects-as well as
tolerance to drought and flood.
"Although it's not even close to
extinct, there's less than there used to
be in this country," Kindiger says.
"Domestic cattle have destroyed it in
many places, eating it to the ground.
They like it as much as buffalo did,
but the roaming herds of buffalo used
to move on before they finished the
plants off.
"And much of the prairie grass has
been plowed under to grow corn and
soybeans. But you can see gamagrass
all over ditches on Interstate 70
between Kansas and Missouri. It is a
very, very unique plant."
The successful cross-breeding of
gamagrass and corn by Kindiger and
Chet Dewald, an agronomist and
plant breeder-along with a 15-


Agronomist Chet Dewald checks a corn-eastern gamagrass hybrid that is being grown in a
project to map the genes that control aerenchyma formation and apomixis, or asexual
reproduction by seed.


species collection of gamagrass and
several strains of teosinte-led ARS
plant physiologist Jeffrey D. Ray to
spend a week at Woodward last year.
Ray says his lab was inspired by
the Spaulding farm dig. His col-
league, plant physiologist Thomas R.
Sinclair, was on that expedition.
Sinclair and Ray and colleagues are
looking for aerenchyma in various
types of sugarcane and corn plants.
"Aerenchyma is already very
common in sugarcane, but breeding
improvements are needed," says Ray.
"There's a special importance to this
work because if sugarcane can
produce in higher water tables, we
can slow down the degradation of
muck organic soils.
"We are losing about an inch of
organic soil a year to rapid decompo-
sition caused by exposure to air from
drainage," Ray says. "The Everglades
Restoration Project is very much
interested in creating sugarcane that
can grow in the Everglades with
minimal drainage.
"We went to Woodward to see
how prevalent aerenchyma was under
well-aerated conditions, because
many plant species such as corn have
varieties that will produce aerenchy-
ma tissue when flooded," says Ray.
"We're interested in the kind of
aerenchyma plants develop soon after
sprouting. Also, we wanted to see if
aerenchyma occurred in the offspring
of the teosinte-corn crosses."
Ray and his colleagues pulled up
plants, sliced them with razor blades,
and viewed the cross sections under a
microscope. They found aerenchyma
in the teosinte-corn offspring, as well
as in all of the eastern gamagrass
growing on well-aerated soils.

Guarded Optimism
Ray cautions that while he and
Sinclair are excited by the possibili-
ties, "at this early stage there is no


Agricultural Research/August 1997







4 Dark openings in this cross section of eastern gamagrass root are air
passages that form in aerenchyma tissue and enable plants to grow in
flooded conditions. The actual root size is 1.5 mm (about one-sixteenth
inch) across.


proof that aerenchyma is
always beneficial to
plants. In fact," he says,
"we have found that
aerenchyma may be a
negative trait for sugar- KEITH WELLER (K
cane grown on sandy
soils in south Florida.
Our experiments demon-
strate that aerenchyma tissue makes
sugarcane more sensitive to drought.
"While it can help plant roots
thwart drought by penetrating hard
layers, it could be a detriment in
times of drought in sandy soils that
are well aerated and well drained and
have no hard layers," says Ray.
Yet, this past summer, VanToai
grew soybeans with aerenchyma in an
artificially flooded field in Columbus.
The plants, offspring of plants that
survived a "flood of the century" in
China in 1991, thrived-despite
being partially submerged the entire
season, beginning 2 weeks after the
seedlings sprouted.
In a project sponsored by the U.S.
Soybean Board, VanToai is working
with 10 other scientists across the
country to breed new varieties of
these flood-and-drought-tolerant
soybeans within 4 years. They have
screened 230 soybean lines for DNA
markers linked to flooding tolerance
and have identified several.
VanToai analyzed eastern gama-
grass samples taken both from the
Shepherd farm in Cliftonhill, Missou-
ri, where it survived the flood of
1993, and from samples at another
location that was not flooded. She
found that the Shepherd farm samples
had more aerenchyma.
Dan Shepherd is not surprised. He
traces his 1,200 acres of eastern
gamagrass back to a clump of un-
known grass his father found in clay
soil surviving a killer drought in
1980, a drought that baked all other
grasses and plants to death with
temperatures up to 112F.


biologist identified the
grass, Shepherd went to
Dewald at Woodward
for help in growing
1) eastern gamagrass. The
USDA Plant Materials
Center in Manhattan,
Kansas, gave him Pete,
or PMK-24, the eastern gamagrass
variety that he started his prairie
pasture with. Now he sells the seed
and fattens up all 700 of his buffalo
herd on gamagrass for 8 or 9 months
out of the year.
Box, who retired in 1996 but is
still doing collaborative research,
says the discovery of aerenchyma in
eastern gamagrass has a significance
that goes well beyond the practical
implications for growing gamagrass.
"It convinced people that aerenchyma
is an important mechanism that
should be incorporated into major
crops," he says.


Penetrating Hardpan, Acid Soils
When he started studying aeren-
chyma in wheat in the 1980s, Box
found it hard to convince plant
breeders or farmers of its practical
use, because they didn't recognize
lack of oxygen in soil as a significant
yield robber.
Box says his work at the ARS
Southern Piedmont Conservation
Research Center in Watkinsville,
Georgia, convinced him that lack of
oxygen in a wet, restrictive layer
during the winter months was the
reason winter wheat in the Southeast
roots shallowly and yields only 30 to
35 bushels an acre-barely at the
break-even level, when it should be
yielding 100 to 200 bushels.
Farms that should have tremen-
dous yields of wheat, corn, or soy-
beans have been planted with trees or
overrun with weeds because of the
combination of summer drought and
a restrictive soil layer, says Box.


SCOTT BAUER (K7703-1)


Visiting scientist Victor Sokolov from the Institute of Genetics in Novosibirsk, Russia,
analyzes chromosomal variations in the root tip cells of corn-eastern gamagrass hybrids.


Agricultural Research/August 1997













Acid soils and hardpan layers
restrict root growth, not only in large
portions of the Midwest and the
Southeast, but also in most of the
eastern United States, where there is
enough rainfall to at least meet crop
needs. This amounts to a total of
more than 250 million acres.
"Worldwide, acid soils make up
about 10 billion acres," says Dale A.
Bucks, the ARS national program
leader for water quality and water
management. "This restriction limits
the water available to crops, resulting
in drought and lower yields in areas
with otherwise enough rain for the
best yields."
Charles D. Foy, one of the pio-
neers in finding crops that will
tolerate acid soils, agrees that shal-
low rooting caused by acid soils and
hard layers-as well as other associ-
ated factors, such as aluminum
toxicity and low oxygen-is an
important yield-limiting factor for
crops worldwide. He has found that


Visiting scientist Sergiu Cealic from the
Republic of Moldovia works on genetic
mapping of eastern gamagrass. If the
specific location of the genes that control
aerenchyma can be found, those genes
may eventually be transferred into corn.


Flood-tolerant soybeans from southeastern China show no injury in this field test of 20
domestic and Chinese lines. Each line was planted in a 4-foot row and flooded
continuously for 8 weeks.


eastern gamagrass roots are very
tolerant of soil acidity.
"Its roots grow well in soils with
pH in the range of 4.2 to 5.0, which
is common for claypans and other
restrictive layers and is toxic to roots
of most crops," says Foy.
He suspects that oxygen brought
into the soil by the gamagrass roots
might be rendering toxic forms of
minerals such as iron and manganese
harmless by oxidizing them to less
soluble forms.
Ralph B. Clark, an ARS plant
physiologist at Beaver, West Virgin-
ia, who has devoted his career to
finding ways to grow plants on acid
soils, says eastern gamagrass may
also rely on beneficial fungi, called
mycorrhizae, on its roots to help
ameliorate aluminum toxicity. He
found high numbers of them on root
samples from the Great Dig. Myco-
rrhizae also help plants acquire
essential nutrients under very defi-
cient conditions, such as those in
subsoil.
Jean L. Steiner, who heads the
Watkinsville lab, is continuing Box's
research, working with Box and Jerry
Johnson, a plant breeder at the
University of Georgia at Athens.
They are field-testing wheat types
with aerenchyma bred into them and
expect to have commercial varieties
in 2 years.
Steiner says the breeding tech-
niques Johnson is using with soft red
winter wheat would apply to all other
types of wheat.-By Don Comis.
For questions about this article,
contact E. Eugene Alberts, USDA-
ARS Cropping Systems and Water
Quality Research Laboratory,
University of Missouri, Agricultural
Engineering Bldg., Columbia, MO
65211; phone (573) 882-1144, fax
(573) 882-1115. *


Agricultural Research/August 1997









Mouth-Watering New Fruits


At the Horticultural Crops Research
Laboratory in Fresno, California, more
than 50 flavorful summer fruits have been
developed by horticulturist David
Ramming and other ARS scientists.


Commercial vineyards have planted more
than one million of the ARS-developed
Crimson Seedless grapevines.


even new, sweet-tasting fruits
rate as top performers in
orchard trials and informal
indoor taste tests.
Using conventional breeding
techniques and-in some cases-a
lab procedure known as embryo
rescue-scientists at the ARS Horti-
cultural Crops Research Laboratory
in Fresno, California, have within the
past few years produced three juicy
new peaches, two tasty nectarines, a
flavorful grape for fall, and a robust
new apricot.
Each new variety is derived from
about a decade of scrutiny in com-
mercial or research orchards or
vineyards inJACK DYKINGA (K6084-1)
California. The
state ranks first
nationally in
production of each
of these crops.
And the San
Joaquin Valley,
where the ARS
tests were cen-
tered, is Califor-
nia's premier
growing region for .
all of these fruits.
Small quantities
of some of the
fruits have already
been marketed by
growers who
provided orchard Autumn Red peach.
space for experi-
mental trees or
vines. Those tests took place while
the plants were candidates for new-
variety status and were known by
research numbers instead of names.
Today, the new varieties have already
been named and offered to growers
nationwide as cuttings.
If the fruits meet grower needs, it
may take another 5 years or so before
enough trees or vines are planted and
sufficient fruit harvested to market
nationwide.


The plump new peaches-Spring
Baby, Spring Gem, and Autumn
Red-and the nectarines Crimson
Baby and September Free are the
work of Fresno horticulturist David
W. Ramming and his retired col-
league, Owen L. Tanner.
Spring Baby peach is a bold
experiment: It represents the first
time the Fresno team has released a
peach with canning clingstone flesh
for fresh-market sales.
Says Ramming, "Normally, fresh-
market peaches for eating out-of-
hand are freestones, the kind with
flesh that softens quickly and doesn't
stick to the pit. But we're offering
Spring Baby
clingstone as a
fresh-market
peach because it
remains firm
longer and tastes
better than most
c c of the other U.S.-
grown freestones
available that
time of year
that is, around the
S"first week of
May."
The idea of
marketing a
clingstone as a
fresh-market
peach isn't new,
but it hasn't yet
become routine in
California.
Firm, round, and attractive, Spring
Baby peaches are about 2-1/2 inches
in diameter when ripe, with an
appealing, bright-red blush or over-
color covering much of the fruit's
surface. Spring Baby has very
smooth skin and isn't plagued by
split pits-a costly problem common
to other early-season peaches.
Spring Gem peaches, ready at the
end of May, are attractive, semi-
freestone peaches for the early-


Agricultural Research/August 1997












season fresh market. Larger than
Spring Baby, the Spring Gem fruit
may be up to 3 inches in diameter
when ready to eat. Like Spring Baby,
Spring Gem also boast a bright-red
blush on 30 to 50 percent of their
surface when ripe.
Both Spring Baby and Spring Gem
have pleasantly firm flesh when ripe.
That's an advantage over many other
early-season peaches, which are often
soft and difficult to ship without
bruising.
Spring Baby and Spring Gem trees
were once extremely undersized
embryos that Ramming and colleague
Richard L. Emershad carefully
removed from the developing stone,
or pit, then nurtured on a gel-like bed
of nutrients.
"We almost always have to use
this embryo rescue procedure to
develop very-early-season treefruits
and seedless grapes," says Ramming.
"When we cross early-fruiting
parents, the resulting embryo is
usually so tiny that it probably
wouldn't survive without our help."
The scientists' ongoing push for
new, early-maturing fruits means
winter-weary consumers can enjoy a
wider selection of American-grown
fruits sooner in spring than ever
before.
The researchers want to widen the
range of choices available to shop-
pers at the end of the treefruit and
table-grape season, as well. Though
California peaches can sometimes be
ready to harvest as late as October,
depending on the weather, peaches
that ripen in August are already
considered late season. That's the
ripening window for ARS' Autumn
Red peaches, which are ready for
salads, snacks, or desserts by the
third week of August.
These large freestones have
yellow-orange flesh that's red only at


the pit. And they're what growers
call fully blushed-most of the
yellow skin is covered with a dark-
red overcolor. "Autumn Red," says
Ramming, is one of several new
varieties offered to meet the demand
for high-red-blush peaches late in the
season."
Early-season nectarines are often
undersized, misshapen, and ruined by
broken pits. That's not the case with
the new Crimson Baby nectarine. It


Autumn Royal, a new seedless grape.


bears generously sized (about 2-1/2-
inch) fruit.
Large, round Crimson Baby
nectarines have clear, yellow flesh.
The nectarine's pretty red overcolor
may tint nearly 90 percent of the
skin, and sometimes it is lightly
dusted with speckles.
Even though California orchards
produce more than 150 kinds of
nectarines, there's still room at the
end of the season for new, good-
tasting varieties. "The majority of
nectarines that ripen in August and
September," says Ramming, "are


clingstones. Our new September Free
nectarines provide a very firm, top-
quality freestone fruit that's ready to
harvest about the last week of August
or the first week of September."
Ramming says trees of this
promising new, red-blushed fruit
were "vigorous and productive in
yield trials."
These fruits join the ranks of 26
other treefruits and grapes developed
at the Fresno laboratory during the
past 25 years for commercial growers
and backyard gardeners alike. Those
varieties include Flavorcrest, today
the third most widely grown fresh-
market peach in California; Fantasia,
which places among the top 20
California nectarine varieties; and
Flame Seedless, the nation's most
popular red seedless grape.
The newest grape from the Fresno
scientists is Autumn Royal, a black-
to-purple-black, generally seedless
grape for fall. Ramming worked with
research technician Ronald E. Tarailo
at Fresno to produce this crisp,
sweet-tasting grape. It ripens in the
first to second week of October, near
the very end of the table-grape season
for U.S. producers. And because it
stores well, it can be marketed into
December.
"Autumn Royal," says Ramming,
"is ready to eat at a time of the year
when shoppers really don't have a lot
of high-quality seedless grapes to
choose from. Even after winter
begins," he says, "this delicious
grape will give you a taste of sum-
mer."-By Marcia Wood, ARS.
David W. Ramming and col-
leagues are at the USDA-ARS
Horticultural Crops Research
Laboratory, 2021 S. Peach Ave.,
Fresno, CA 93727; phone (209) 453-
3061, fax (209) 453-3088, e-mail
dlramm@qnis.net *


Agricultural Research/August 1997









New Robada's a Superb Apricot


CRAIG LEDBETTER


Big and juicy Robada apricots
give U.S. growers an alternative to
the five standard varieties of
this fruit grown commercial-
ly in the United States today.
"Robada," says Agricul-
tural Research Service
geneticist Craig A. Ledbet-
ter, "has a pleasant balance
of natural sugars, acids, and
aromatic compounds.
People who've tasted it think
it's outstanding!
"Robada offers more flavor
and aroma than many other com-
mercial apricots. And it ships
well," says Ledbetter, who is at the
ARS Horticultural Crops Research
Laboratory in Fresno, California.
The jumbo fruit is intended for
fresh-market sales, though further
testing may reveal that it is also
suitable for drying, canning, or
freezing.
Robada ripens in mid-May
through nearly the end of the
month-"the peak of the California
apricot harvest," Ledbetter says.
The apricot's firm, finely textured
flesh is an attractive deep orange. A
bright-red blush may tint nearly half
of its surface, depending on how
much sun reaches the fruit during
ripening.
Like most other commercial
apricots, Robada is self-pollinating,
meaning that each tree will bear
fruit without the need for other
apricot trees to be planted nearby as
pollen sources.
Robada is the result of four consec-
utive hybridizations of different sets
of parent trees. Those crosses, made
by horticulturist David W. Ramming
of the Fresno laboratory, were fol-
lowed by 8 years of orchard observa-
tion by Ledbetter and Ramming.
ARS has obtained a patent for the
apricot. Commercial nurseries can
apply to the ARS Office of Technol-


9*


y


ogy Transfer for a license to produce
Robada trees.
Though the Fresno research
results apply primarily to California
orchards, Robada might be suitable
for other U.S. regions where apricots
are grown. California produces
nearly all of America's apricots. The
state's 1996 harvest of 76,000 tons
was worth $32 million to growers.-
By Marcia Wood, ARS.


PF Robada apricot trees
produce jumbo fruit
for fresh-market sales.




For further information about
U.S. Plant Patent Number 9,890,
"Apricot cv. Robada, contact Craig
A. Ledbetter, USDA-ARS Horticul-
tural Crops Research Laboratory,
2021 S. Peach Ave., Fresno, CA
93727; phone (209) 453-3064, fax
(209) 453-3088, e-mail
jlitster@qnis.net *


Agricultural Research/August 1997


7






JACK DYKINGA (K7087-19)


When you play with your
children on the front lawn,
feed your livestock on
pasture, or play a round of golf with
friends, you're likely enjoying a little
bit of Oregon. That's because most of
the nation's cool-season grass seed
comes from the Pacific Northwest.
Farmers grew over one-half-billion
pounds of grass seed in 1995-most
in Oregon's Willamette Valley.
Several species of ryegrass, fescue,
and bluegrass make up most of the
turf and forage crops.
But growing the seed is getting
tougher. After this year, Oregon seed
growers can use their most important
farming tool-fire-only on a very
limited acreage.
Field-burning each year after
harvest controls weeds, removes
leftover grass straw, and destroys
diseases, including growers' nemesis,
blind seed disease. Infected plants
look normal, but many of the seeds
won't germinate.
"Blind seed disease was inadvert-
ently introduced, most likely from
New Zealand, in the 1930s," says
ARS plant pathologist Stephen C.
Alderman. "By 1944, about 90
percent of the seed fields were
infected, and only 13 percent of the
seeds in some ryegrass crops germi-
nated." Alderman works at the ARS
National Forage Seed Production
Research Center in Corvallis, Oregon.
"Burning fields between harvests
completely controlled blind seed
disease and is largely credited with
saving the state's grass seed indus-
try," Alderman says.
In 1995, grass seed ranked fifth in
agricultural production for the state,
worth $236 million.
Jack Pimm, a third-generation
grass seed grower, heard his grand-
father and father talk about blind seed
disease when he was a child. But in
1995, he saw the devastation first
hand in his field near Halsey, Oregon.


"Only 70 to 75 percent of the seed
germinated. That was unheard of," he
said. The seed was from Pimm's
1994 crop, grown in a field that had
not been burned for 6 years. Through
the Oregon State University Exten-
sion Service, Alderman heard of the
problem and came in to help discover
the cause.
"Sure enough, we had blind seed
disease," Pimm says. To stop the
disease in its tracks, he burned four
of his fields and adopted new man-
agement techniques. Fortunately,
Pimm was able to sell his seed-but
at a substantial loss.
If field burning is so effective,
why are growers phasing it out?


As the valley's population expand-
ed in the 1960s, residents began to
complain about the smoke-filled
summer air. But it was a tragic
accident that set the stage for chang-
ing growers' management practices.
"In 1988, smoke from a wildfire-
believed to have started when the
wind blew burning grass straw out of
control-covered Interstate 5 south
of Salem, Oregon," says David
Nelson, executive secretary of the
Oregon Seed Council. "A chain
collision resulting in several deaths
and injuries mobilized the industry,
legislators, and the public to negoti-
ate a phase-down of field-burning."


Agricultural Research/August 1997

















































Before 1991, growers burned up to
250,000 acres per season in the
valley. The allowable burned acreage
has decreased incrementally since
then and will be limited to 40,000
acres, plus up to 25,000 acres of
steep terrain as identified by the
Oregon director of agriculture.
Grass seed farmers in eastern
Oregon, Washington, and Idaho may
face similar restrictions in the future.
At first, growers worried that
instead of diseases and weeds, their
businesses would go up in smoke.
"The industry was very uncertain
it would be able to make the change,"
Nelson says.


Alderman and other ARS, univer-
sity, state, and private researchers are
helping grass growers produce a
viable seed crop.
"Now there's a feeling of confi-
dence that we've solved enough of
the problems to produce the same
quality of grass seed without burning
all our fields," Nelson says. "ARS
has greatly helped the industry make
that transition."
But the challenges are ongoing:
the return of diseases, contamination
of the seed crop by weeds, and a
million tons of straw left each year
after harvest.
ARS scientists are working hard
on all three fronts. Alderman has


monitored fields since 1988 to detect
flare-ups of blind seed and ergot,
another serious fungal disease that also
destroys flowers and seeds.
"Early detection and treatment are
very important to prevent the sudden
increase and spread of diseases," he
notes. No chemical treatments effec-
tively control these diseases, but Al-
derman says specific plowing and
planting techniques should keep them
largely at bay without routine burning.
Two new lines of tall fescue will
help growers combat another disease,
stem rust. This rust attacks the stems
and leaves, rather than the flowers, and
can reduce seed yields by as much as
80 percent, says ARS plant pathologist
Bill Pfender.
Growers spend nearly $27 million
annually on fungicides to control stem
rust on grass seed crops. The new tall
fescue lines resist rust disease up to 10
times better than existing varieties. In
laboratory tests, more than half of the
plants from the new lines showed rust
resistance, compared to only 5 percent
of plants from older cultivars. ARS
geneticist Reed E. Barker and plant
pathologist Ronald E. Welty, who is
retired, developed the fescue lines.
"Increasing the number of plants in
a variety that are resistant to stem rust
can stop or slow development of a
disease epidemic," says Barker.

Managing Weeds, Certifying Seeds
Unlike most crops, grass is often its
own worst weed.
"Grass plants are not neat and tidy
like wheat or corn," says ARS agrono-
mist George W. Mueller-Warrant.
"Tillers and seeds on the same plant
mature at different times, and there's
no way the grower can get all the seed
to the same ripeness simultaneously."
Growers time their harvest to get the
best yield. But previously ripened seed
heads that have shattered and tiny
seeds that fall through the combine can


Agricultural Research/August 1997





BRIAN PRECHTEL (K7715-1)


mean that up to one-fourth of the total
seed production lands back on the
field.
"Many of the grass seed crops are
perennial, and anything that germi-
nates among the established plants is
undesirable," Mueller-Warrant says.
The reasons are genetic. About half
of Oregon's seed is produced under a
certification process managed by Ore-
gon State University.
To participate, growers submit re-
quests for each field they want certi-
fied. Then the Certification Service re-
views crop production records and
conducts a series of field and laborato-
ry evaluations. If the field meets the
review criteria, it can be certified.
"The industry has more than 1,250
varieties of grass seed eligible for cer-
tification, and about half of those were
in production in 1996," says Ronald
Cook, head of the Oregon Seed Certi-
fication Service. "Our job is to ensure
that the customers are getting the vari-
ety and product performance that they
are expecting." Growers, in turn, can
command higher prices for their seed
and reach expanded markets by grow-
ing certified seed.
One obstacle to certification is ge-
netic contamination.
If a seed falls off the grass plant
and germinates, it is the progeny of the
original plant. "These 'children' are
weeds," says geneticist Barker. He
notes that grass is wind-pollinated, so
the parent and seedling are easily
crossed. "This crossing may cause un-
wanted genetic shifts."
Cook says that in most crops, more
than 1 or 2 percent genetic contamina-
tion can jeopardize certification. Bark-
er is working with Cook to determine
if these standards make sense from a
genetic standpoint. Using molecular
DNA markers, Barker is examining
how much genetic shift is actually tak-
ing place.
But at least some shift is likely over
time, so weed control will always be
necessary.
14


Plant pathologists Stephen Alderman (left) and Bill Pfender compare rust-resistant tall
fescue (in top of magnifying lens) with a susceptible variety.


"At the same time as the growers
lost field burning, they lost several of
the chemicals they were using on
weeds," says Mueller-Warrant. He's
studied over 20 alternatives to the
herbicides that were not reregistered
by the U.S. Environmental Protection
Agency or that were taken out of pro-
duction because of environmental
concerns.
His tests show three as the most
promising: oxyfluorfen, metolachlor,
and pendimethalin. The first received
an emergency registration under the
tradename Goal in 1989. Mueller-
Warrant says that chemical best con-
trols a large flush of weeds germinat-
ing after heavy rains.
Metolachlor, known under the
tradename Dual, was registered last
year. The last and newest will be reg-
istered as Prowl.
"Pendimethalin will probably be
the most useful for the grower. In
field tests, it provided close to 100
percent control of seedlings with little
crop injury," he says.
Biological control also looks
promising for controlling annual
bluegrass weeds in ryegrass and tall
fescue crops and in cheatgrass or
downy brome, a noncrop grassy weed
infesting Kentucky bluegrass stands.
ARS soil scientist Lloyd F. Elliott
and colleagues in Corvallis and Pull-
man, Washington, have discovered


weed-killing bacteria that live natu-
rally among the plant roots.
"In laboratory and growth chamber
tests, the bacteria provided virtually
100-percent control of the undesir-
able species," Elliott says. He's ready
to test six of the bacteria in the field.

What To Do With Residue
While the burning phaseout in-
creased weed and disease problems, it
also gave growers an entirely new-
and perhaps the toughest-challenge:
managing 1 million tons of grass
...- ...la~ I-. I. I,


Weed scientist George Mueller-Warrant
assesses the effectiveness of weed control
practices in this field of perennial ryegrass
grown for seed.


Agricultural Research/August 1997






BRIAN PRECHTEL (K7719-6


Using DNA-profiling equipment, technician Lori Evans and geneticist Reed Barker can
identify genetic contamination among grass plants in seed-production fields.


straw annually. After harvest, a blan-
ket of plant stalks, or straw, covers
the field. Burning eliminated the
straw and stimulated regrowth of
next year's crop.
Unless the straw is removed from
the crowns of perennial grass plants,
the crowns don't receive enough
light, Elliott says.
Straw left on the field also limits
herbicide effectiveness.
About a third of the straw can be
sold for animal feed and bedding, but
the supply far exceeds demand.
Elliott and ARS agricultural engi-
neer Donald B. Churchill proved for
the first time that low-input, on-farm
composting of the high-carbon straw
was possible. Their method involved
gathering the straw in large windows
alongside the field and turning them
three or four times with a tractor-
mounted front-end loader.
"Before our experiments, it was be-
lieved that you would have to add ni-
trogen before the straw would decom-
pose. There was also concern that the
compost wouldn't reach high enough
temperatures to kill weed seeds and
inhibit diseases," Elliott notes.
Growers discovered that they
could also leave the straw on the field
to decompose in place, if they
chopped it fine enough that the grass
crowns weren't covered. Another
ARS research project addresses the
variation in crop needs and environ-


mental conditions across the Wil-
lamette Valley and drier grass-grow-
ing regions of the Pacific Northwest.
"The southern part of the valley
has poorly drained soils that are very
wet in winter," says ARS agronomist
Jeffrey J. Steiner. He's coordinating
a long-term sustainable cropping sys-
tems program with scientists from
ARS, Oregon State University, and
the USDA's Natural Resources Con-
servation Service; extension special-
ists; and growers.
The south valley supplies most of
the annual and perennial ryegrass
seed. The moderately drained soils to
the north allow more crop diversity,
and growers farm tall fescue seed as
a major crop. Well-drained hilly ar-
eas produce fine fescue seeds, but
these soils erode easily if not man-
aged properly.
In each of the three regions, Stein-
er and colleagues are looking at the
best methods for managing straw
(cutting and leaving on the field ver-
sus removing the straw), rotating
crops (grass seed continuously or ro-
tating grass with legume seed crops
and wheat or meadowfoam), and
planting methods (conventional or
no-till).
"One of the main problems is how
to rapidly establish each crop. Other-
wise a grower can go as many as 20
months in the rotation sequence


without an economic return," he says.
The first complete crop rotation
will end this year. But the study has
already provided valuable information
for growers.
"Clover, which fixes nitrogen in
the soil, is a good addition to both a
ryegrass-spring wheat rotation on
poorly drained soils and tall fescue on
better drained soils," says Steiner.
"By strategically growing alternative
crops before the grass seed, we can
break weed and disease life cycles."
Stephen M. Griffith, an ARS plant
physiologist, also looks at nitrogen
use in the seed crops. He and others
have found that as long as chopped-up
straw residue doesn't cover the grow-
ing crowns of the grass plants, it may
help the crop in the long run.
"Over time, the residues contribute
nitrogen to the soils," Griffith says.
"We also have evidence that the mi-
crobial community and soil quality
are improving underneath the straw,"
he adds.
Steiner says all these experiments
should lead to establishing biological
indicators of the health of the soil and
crops. The goal, he says, is to help
growers predict how their fields will
react to specific management changes
so they can maximize both economic
and environmental benefits.
"The loss of field burning and
chemicals required a major change in
how growers produce their crops. We
now have the opportunity to optimize
all aspects of grass seed manage-
ment," Steiner says.-By Kathryn
Barry Stelljes, ARS.
The ARS scientists in this story can
be reached at the USDA-ARS Nation-
al Forage Seed Production Research
Center, 3450 S. W. Campus Way, Cor-
vallis, OR 97331-7102; phone (541)
750-8722, fax (541) 750-8750, e-mail
elliottl@ucs.orst.edu *


Agricultural Research/August 1997








KEN HAMMOND (K7726-1)


Agricultural Research/August 1997









Boosting Ellagic Acid in Strawberries


Strawberries have long been
associated with good health.
Of course, until recently no
one knew that eight medium-size
berries contained only 30 calories
and had absolutely no saturated fat,
cholesterol, or sodium-or that they
were high in folate, overflowing with
vitamin C, a good amount of dietary
fiber and potassium, and traces of
calcium and iron.
Until this century, it was not
known that strawberries contain
ellagic acid-a natural organic
compound that some studies have
shown to have a beneficial health
effect. [See "Building a Better
Strawberry," Agricultural Research,
September, 1991, pp. 24-25.]
ARS scientists at Beltsville, Mary-
land, and Poplarville, Mississippi, are
studying the genetics of different
strawberry varieties, hoping to breed
more ellagic acid as well as other
beneficial nutrients into the fruit.
"We don't know how ellagic acid
is inherited, but for several years
we've been studying strawberry fruit
and all parts of the plant to determine
where the highest amounts of the
acid accumulate," says John L. Maas.
A plant pathologist with the ARS
Fruit Laboratory in Beltsville, Maas
and colleagues Gene J. Galletta and
Shiow Y. Wang have evaluated 36
strawberry varieties for ellagic acid
content.
"Interestingly, we found the
highest amounts of ellagic acid in
strawberry plant leaves," Maas
reports. "Leaves of Tribute and
Delite, two varieties introduced by
ARS, showed more of the compound
than any others tested. Seeds, in
general, showed more ellagic acid
than fruit pulp, and pulp from green
strawberries contained more than
pulp from red, ripe fruit."
Although the manner of inherit-
ance of ellagic acid is not known, this
study showed that the amount of the


compound varies significantly by
strawberry variety.
"This means that we now know we
can breed for high ellagic acid content
in fruit, where it is most needed,"
Maas explains.
According to Gary D. Stoner, who
is with the Department of Preventive
Medicine at Ohio State University in
Columbus, the beneficial health
effects of ellagic acid have not been


adequately determined. So he and
colleagues tested the compound in its
pure form for anticarcinogenic and
antimutagenic effects. In pure form,
ellagic acid is highly insoluble and
biologically unavailable.
However, Maas says that ellagic
acid, as it is biosynthesized in plants,
occurs in combination with glucose as
ellagitannins. These compounds are
quite water soluble and biologically
available.
"This means that relatively small
amounts of ellagitannins may be more
effective in the human diet than large
doses of ellagic acid," Maas reports.
"Strawberry fruit produce at least five
ellagitannins, but their chemical
structures and their effectiveness as
anticarcinogens have yet to be deter-
mined.


"Dr. Stoner just completed a study
to test the effectiveness of natural
ellagitannins from dehydrated
strawberry fruit added to diets of rats
to protect against some forms of
cancer, especially esophageal," says
Maas. "The diet significantly re-
duced the incidence of chemically
induced tumors in the esophagus.
Stoner and colleagues believe that in
addition to ellagic acid, other com-
pounds in the fruit contributed to the
positive results."
In a collaborative study with the
National Cancer Institute, Stoner and
colleagues found ellagic acid in
raspberries, blackberries, cranberries,
walnuts, and pecans.
"Although we don't yet know
how much ellagic acid would need to
be consumed to produce beneficial
results, these studies indicate that a
diet containing these foods would
certainly be recommended," says
Stoner.

Upping the Berries' Quotient
Now that it is known that ellagic
acid does exist in strawberry fruit,
seeds, and leaves, other ARS scien-
tists are seeking ways to increase the
amounts.
At the Small Fruits Research
Station in Poplarville, plant patholo-
gist Barbara J. Smith and horticultur-
ist James B. Magee are looking at
the effect nitrogen may have on
ellagic acid in two strawberry
varieties. And in collaboration with
Roy J. Constantin, Director of
Louisiana State University's Ham-
mond Research Station, they're
adding several types of soil amend-
ments to strawberry plots to study
their possible effect on ellagic acid
content.
In a greenhouse study, Smith and
Magee fertilized potted Chandler and
Pelican strawberry plants with
nitrogen-rich ammonium nitrate,


Agricultural Research/August 1997





KEN HAMMOND (K7727-1)


urea, calcium nitrate, and ammonium
sulfate. The control plants received
no nitrogen.
"We found no difference in ellagic
acid content of ripe fruit harvested
from plants grown in all sources of
nitrogen. However, we did find
differences between strawberry plant
varieties: Chandler produced about
twice as much as Pelican," Magee
reports. "We're still analyzing data
for more details."
In the Hammond study, Magee and
Constantin have been adding several
amendments to the soil. Initially, they
applied one of the following to each
strawberry test plot at the rate of 10
tons per acre: hardwood bark, cotton-
wood bark, crab meal, sewage sludge,
and waste generated from processing
cottonseed.
"Our soil is very low in organic
matter, and we're hoping to increase
the levels with these additives,"
Constantin says. A study completed
with these same amendments last
year showed no significant changes in
strawberry yield.


Pelican, one of the two straw-
berry varieties used in the Poplar-
ville ellagic acid studies, was de-
veloped and released by Gene J.
Galletta and colleagues. Galletta
is a plant geneticist at the ARS
Fruit Laboratory in Beltsville.
Now winding down his career,
Galletta plans to retire from ARS
in January 1998. He has devel-
oped and released 21 strawberry
varieties for growers and 4
disease-resistant strawberries for
breeders. In addition, he has
released 21 new blueberries, 3
thornless blackberries, and a
raspberry.
Galletta introduced five new
strawberry varieties in 1994 and
1995: Delmarvel, Latestar, Mohawk,
Northeaster, and Primetime. Pelican
and Winona are his newest introduc-
tions, released in 1996.
Pelican, resistant to anthracnose, a
major strawberry disease, was
developed in conjunction with
researchers from the Louisiana
Agricultural Experiment Station,
North Carolina Agricultural Research
Service, and ARS' Small Fruits
Research Station at Poplarville,
Mississippi.
"Pelican is best adapted to the
southern Coastal Plain and lower
Piedmont, especially for fall planting
and late winter and early spring
production," Galletta says.
Researchers at the University of
Minnesota worked with Galletta for
15 years to produce a strawberry
specifically adapted to the environ-
ment of the north-central region of
the United States.
"We needed a variety that would
fit into an integrated pest manage-
ment program that included minimal
use of chemicals to control pests and
diseases," Galletta says. "And we
needed winter-hardy plants that could
resist most pathogens."


Plant geneticist Gene Galletta and plant
pathologist Barbara Smith evaluate
Chandler strawberries for growth and
ripening characteristics.

Winona, released in 1996, is the
fruit of their labor. The result of
cross-breeding that included Earli-
glow and Lateglow, two of USDA's
earlier releases, Winona has consis-
tently produced large, bountiful fruit
in Minnesota field tests.
Researchers have applied for a
patent for Winona, which is now
available in nurseries.
"My collaborators think Winona
may replace Blomidon, a strawberry
variety that was popular in Minneso-
ta before it showed symptoms of the
physiological disorder June Yel-
lows," says Galletta.-By Doris
Stanley, ARS.
Gene J. Galletta and John L.
Maas are at the USDA-ARS Fruit
Laboratory, Bldg. 004, 10300
Baltimore Ave., Beltsville, MD
20705-2350; phone 301-504-5652,
fax 301-504-5062, e-mail
galletta@asrr.arsusda.gov and
jmaas@asrr.arsusda.gov
Barbara J. Smith and James B.
Magee are at the USDA-ARS Small
Fruits Research Station, P.O. Box
287, Poplarville, MS 39470; phone
601-795-8751, fax 601-795-4965, e-
mail bjsmith@ag.gov and
jmagee@ag.gov *




LILA DE GUZMAN (K5069-21)


\ -


Bee Mites


Beekeepers have a long-established
practice of using smoke to calm their
bees before opening the hive. Now
U.S. Department of Agriculture
scientists have found another potential
benefit from smoke: Some plants,
when burned, give off natural chemi-
cals that control honey bee mites.
Frank A. Eischen, an entomologist
with USDA's Agricultural Research
Service in Weslaco, Texas, has found
that smoke from certain plants either
kills varroa mites or causes them to
fall off the bees.
This mite began infesting honey
bee colonies in the United States in
the 1980s, was discovered in 1987,
and has since become the biggest
threat to managed honey bees. The
mites attach to bees and feed on their
blood. If the infestation is severe and
left untreated, the mites usually kill
the colony.
The standard treatment for the
mites is fluvalinate, a synthetic
pyrethroid harmless to the bees. Bee-
keepers put fluvalinate-impregnated
strips in their hives to kill mites, but
they can use the strips only during
times when bees are not making
honey. Otherwise, the chemical could
contaminate it.
Another problem with fluvalinate is
that European researchers have
reported that mites are developing
resistance to the chemical.
Several years ago, Eischen began
looking for alternative controls for
mites. So far, he has tested smoke
from about 40 plants. The first one he
tried was a desert shrub called creo-
sote bush, native to Mexico, Texas,
and other areas of the Southwest. A
Mexican beekeeper, David Cardoso,


)ut


had recommended that Eischen test
the olive-green plant, known in
Mexico as gobernadora.
Eischen set up a standard lab test,
placing 300 to 400 mite-infested bees
inside a cage and covering the cage
with a plastic container. Then he put
the plant material inside his smoker,
lit it, puffed the smoke into the
container, and corked the plastic
container opening to prevent the
smoke from escaping.
He kept the smoke inside for 60
seconds, then removed the bees.
Next, he placed the bees over a
white, sticky card to catch any mites
that fell off the bees.
"Lo and SCOTT BAUER (K5111-10)
behold, the
smoke from
creosote bush
was knocking
down mites
right, left, and
center,"
Eischen says.
"It gave us the
idea to start
looking at other
plants that,
when burned,
give off chemi-
cals that re-
moved the
mites without
harming bees."
harming bees." Varroa jacobsoni mite.
Among the
40 different
plants Eischen
has tested, the most promising plants
are creosote bush and dried grape-
fruit leaves. Creosote bush smoke
achieves a 90 to 100 percent mite
knockdown after 1 minute, but Eis-


M


Brownish-orange bumps on the backs of
these bees are Varroajacobsoni mites.




chen says that excessive exposure
can harm the bees. "It's similar to
burning tobacco in that respect," he
says. "It's hard to find chemicals that
remove mites without harming bees."
Grapefruit leaves fit that descrip-
tion. After 30 seconds, smoke from
the grapefruit leaves knocked down
90 to 95 percent of the mites in the
cage test. With grapefruit leaves,
however, few of the mites are killed.
Most simply fall off the bees.
"The smoke chemicals either
irritate the mites or confuse them. We
aren't exactly sure," Eischen says.
"But we do know that the grapefruit
leaf smoke doesn't seem to have any
bad effects on the bees at all. The
bees come through fine."
Eischen stresses that the findings
thus far are preliminary. "These are
crude experiments, and we haven't
yet analyzed the active chemicals in
the smoke that knock down the
mites," he says.
"We're not
yet telling
beekeepers to
use these meth-
ods for
controlling
varroa mites,"
says Eischen.
"We're using
these experi-
ments to try to
identify and
isolate the
chemicals that
act as
miticides."-
By Sean
magnified about 30x. Frak, A.
Frank A.
Eischen is at
the USDA-ARS
Honey Bee Research Laboratory,
2413 E. Hwy. 83, Weslaco, TX
78596; phone (210) 969-5005, fax
(210) 969-5033, e-mail
eischen@rsru2.tamu.edu *


Agricultural Research/August 1997








Fungal Rivalry Protects Tomatoes


Tomato plants could get a new
natural ally against pathogen-
ic Fusarium oxysporum fungi
that cause wilt disease.
Using a new experimental ap-
proach, ARS researchers are exposing
the plants' roots to benign saprophytic
strains of Fusarium that prevent their
virulent cousins from causing harm.
The aim is to eventually give
tomato growers a natural alternative
to controlling wilt with methyl
bromide, says Deborah R. Fravel, a
plant pathologist at ARS' Biocontrol


search Center. They also began tests
on Maryland's Eastern Shore, where
some commercial melon fields are
heavily infested with wilt.
Also interested in the Beltsville
work is plant pathologist Dan
Chellemi of the USDA-ARS Horticul-
tural Research Laboratory in Fort
Pierce, Florida. He'd like to test the
beneficial fungi against a virulent new
form of fusarium wilt dubbed Race 3.
Over the past 3 or so years, it has
become a fungal scourge of tomato
crops grown in Quincy and other


Both tomato plants being compared by plant pathologists Deborah Fravel and Robert
Larkin were exposed to the same fusarium wilt pathogen, but the healthy one was
protected by a benign, saprophytic strain.


of Plant Diseases Laboratory in
Beltsville, Maryland.
In greenhouse studies there over
the past couple of years, use of the
helpful fungi reduced the disease by
up to 80 percent in both tomato and
watermelon seedlings.
This summer, Fravel and a col-
league, plant pathologist Robert P.
Larkin, began small-scale field
studies on a half-acre plot located at
ARS' Beltsville Agricultural Re-


locales near the Florida-Georgia line.
Fumigating soil with methyl
bromide has traditionally been the
first line of defense against fusarium
wilt, says Fravel. It is done before
transplanting seedlings from the
greenhouse to crop field. Fumigation
also kills weed seeds, nematodes,
root-attacking insects, and other
soilborne microbes that cause harm.
Other tactics are called on as well.
For example, in Quincy, some farm-


ers have kept Race 3 fusarium wilt in
check by rotating tomatoes with a
grain crop or turfgrass, which the
fungus can't survive on. They also
grow commercial tomato lines with
genetic resistance to the new race,
Chellemi says.
Methyl bromide fumigation re-
mains the primary defense. In fact,
tomato crops account for 25 percent
of the chemical's total use for soil fu-
migation. But its days are numbered.
Starting January 1, 2001, the U.S.
Environmental Protection Agency
will impose a ban on its use for all
domestic crops, not just tomatoes.
The ban stems from concern that me-
thyl bromide depletes the ozone lay-
er, Earth's atmospheric shield against
the sun's ultraviolet light.
Meanwhile, researchers have
joined the fruit and vegetable indus-
try in an intense search for suitable
alternatives. Among these: solariza-
tion, a heat treatment that sterilizes
soil using clear plastic, along with
mulching, crop rotation, and biologi-
cal control.
"Our main emphasis is finding an
alternative to methyl bromide as a
soil fumigant against plant patho-
gens," says Fravel. "Our goal is to
develop an effective biocontrol of
fusarium wilt of tomatoes and some
other crops of economic importance."
Unchecked, wilt fungi waste little
time invading a plant through its
roots and xylem, or vascular water
supply system. The pathogens use the
xylem as a conduit to spread and
grow in the plant, causing blockages
and stealing vital nutrients. Such as-
saults can exact a heavy toll on yield.
But casting certain strains of the
benign Fusarium fungi onto the
scene evens the score, the researchers
found. For one, the protectant mi-
crobes colonize the root system better
than their pathogenic brethren.
"They live on and in the vicinity
of the roots, as well as just inside the


Agricultural Research/August 1997













roots' epidermis, or outer cell layer,"
Larkin explains. There, they crowd
out the competing pathogens for
sugars, amino acids, and other
nutrients both need in order to
flourish.
But the good fungi don't cause
disease, and they're not fungal
freeloaders. In fact, five of the strains
the scientists examined play a very
important role: they jump-start
plants' natural chemical defense
system against the pathogens.

Helping Plants To Help Themselves
Scientists named the phenomenon
"induced systemic resistance." In
greenhouse studies, Fravel and Larkin
observed the response in tomatoes,
muskmelons, and watermelons.
Induced systemic resistance might
be likened to the immune response of
a child vaccinated against a germ-
caused disease. As part of treatment,
a doctor administers a weakened form
or strain of the germ to the young
patient. This stimulates the child's
immune system to make antibodies or
other defensive cells that destroy the
virulent forms.
Plants don't have immune systems,
so they can't make antibodies against
microbes that attack them. But they
can defend them-
selves with natural


antifungal com-
pounds called
phytoalexins and
other antimicrobial
substances.
The trick is to
ensure that plants
muster their defenses
ahead of time-and
that's where the
benign Fusarium
strains play a role. In
this sense, the
microbes serve as a
kind of vaccine for
the plant.


Plant pathologist Ri
Larkin examines a I
culture of the benefit
of the fungus Fusari
oxysporum.


In tomatoes, this may help
plants mobilize compounds that
gum up or block the wilt fungi's
avenue of attack in the xylem. As
a result, the pathogens can't grow,
spread, or cause disease as easily.
To study the phenomenon and
gauge the extent of its protection
to the plants, the scientists must
first grow the good fungi in a
liquid culture. They then apply the
microbes to the roots of potted
watermelon or tomato seedlings at
rates of 100,000 to 1,000,000
spores per gram of soil. The fungi
are given about 2 weeks to fully
colonize the roots.
The treated seedlings are then
transplanted into potting soil collect-
ed from wilt-infected fields. An equal
number of untreated seedlings are
also transplanted, of which less than
half typically escape the disease. But
up to 80-and sometimes 90-
percent of the treated seedlings grow
to mature, wilt-free plants.
The results can vary, depending on
the temperature, humidity, soil type,
and other greenhouse conditions,
Larkin says. "But on average, you get
a 50- to 80-percent reduction in the
disease."
The scientists hope for equal
success in outdoor
studies. A chief interest
is to see how long
obert microbe-colonized
iquid
icial strain plants can maintain their
ium resistant state under
field conditions.
"This kind of thing is
still being investigated,"
says Larkin, referring to
plant scientists' interest
in the phenomenon in
general. He wonders if
the induced resistance is
going to last the whole
season.
Perhaps most impor-
tant, though, is that the


Plant pathologist Deborah Fravel
observes growth of the plant-pathogenic
strain of Fusarium oxysporum that causes
fusarium wilt.

fungi help keep tomato plants wilt-
resistant as seedlings. "The younger
the seedling, the more susceptible it
is to the pathogens," says Larkin.
"Most losses are in the seedling
stage-those 4 to 6 weeks after they
are put in the field."
But harmful microbes are just one
of many plant perils, including
soilborne nematodes and weeds that
vie for sunlight, water, or nutrients.
As an alternative to methyl bro-
mide then, commercial use of the
fungi "would have to be incorporated
with other controls for weeds and
pests like nematodes," says Larkin.
In Chellemi's view, "It's an extra
step you could take to minimize
fusarium wilt. But no one should rely
on a single tactic, whether it's
biological control or resistant variet-
ies or chemical fumigation," he
cautions. "When you do that, you
leave yourself vulnerable."-By Jan
Suszkiw, ARS.
Deborah R. Fravel and Robert P.
Larkin are at the USDA-ARS Biocon-
trol of Plant Diseases Laboratory,
Bldg. 011A, 10300 Baltimore Ave.,
Beltsville, MD 20705-2305; phone
(301) 504-5080, fax (301) 504-5968,
e-mail dfravel@asrr.arsusda.gov *








Enzyme Catalyst for Solventless Winter Wheat Gets New
Extractions Resistance to Hessian Fly


Out with the old and in with the new, as the saying
goes. Now, scientists in the Food Quality and Safety
Research Unit at the National Center for Agricultural
Utilization Research in Peoria, Illinois, have found a
way to significantly reduce the amounts of solvents
used in the laboratory analysis of fat in foods such as
hamburger.
Janet M. Snyder, an ARS chemist, says her pro-
cedure cuts solvent use by as much as 98 percent by
combining supercritical fluid extraction (SFE) with an
enzyme catalyst-lipase.
SFE uses carbon dioxide gas under high pressure,
which causes the gas to act like a liquid. In an extrac-
tion chamber, the fluid flows through a sample and
dissolves specific chemicals-or fats, in the case of
food extractions. The gas is then decompressed and
harmlessly vented into the atmosphere, leaving the
extracted fats behind.
In traditional extractions, scientists must use several
milliliters of solvent and two or more steps to complete
an extraction. By combining SFE and the lipase, the
extraction can be completed in one step and without
chemical solvent. The result is a more accurate fat
reading for specific samples and less waste solvents to
dispose of.
Food researchers are delighted to be released from
their solvent dependency. Like chemists in analytical
laboratories, they routinely perform large numbers of
extractions every day. "Up till now, we've needed as
much as 50 milliliters of solvent-a quarter cup-to
perform one conventional extraction," says Jerry W.
King, an ARS chemist and expert in SFE.-By Dawn
Lyons-Johnson, ARS.
Janet M. Snyder is at the USDA-ARS Food Quality
and Safety Research Unit, National Center for Agricul-
tural Utilization Research, 1815 N. University St.,
Peoria, IL 61604; phone 309-681-6236, fax 309-681-
6679, e-mail snyderjm@mail.ncaur.ncaur.gov *


The Southeast's warmer climate allows up to six genera-
tions of the Hessian fly to breed each season, and that spells
trouble for soft red winter wheat growers.
The Hessian fly, Mayetiola destructor, is considered
wheat's most damaging pest. In 1989, damage from the pest
was estimated at $28 million in Georgia alone.
Plant breeders have been able to give wheat some natural
resistance to the Hessian fly for many years. Now ARS
entomologist Roger H. Ratcliffe in West Lafayette, Indiana,
in cooperation with researchers at Purdue University, has
developed and tested a new cultivar, a variety called Grant,
and eight experimental wheat breeding lines-Carol, Erin,
Flynn, Iris, Joy, Karen, Lola, and Molly-derived from
Newton, a commercial hard red winter wheat susceptible to
Hessian fly. All show improved resistance.
"Grant, a soft winter wheat, offers high yields, improved
disease resistance, and better cold hardiness. It has been
performance-tested in Indiana, Illinois, Missouri, and Ohio
and in the Uniform Eastern Winter Wheat Nursery in West
Lafayette," says Ratcliffe. "Grant's soft wheat milling and
baking scores resemble those of Caldwell, one of the
leading varieties grown in Indiana."
In 8 years of testing, Grant outyielded Caldwell by 4,630
pounds per acre. It also heads, or starts grain formation, I to
2 days later, has shorter, stronger straw, and is more likely
to survive harsh Indiana winters, Ratcliffe says.
Besides leaf rust and powdery mildew, the new wheat
variety resists wheat soilborne mosaic, wheat spindle streak
mosaic, and take-all diseases. Infestation with Septoria leaf
blotch and glume blotch was less severe on Grant than on
Caldwell.
Ratcliffe says the eight breeding lines proved resistant to
one or more of four Hessian fly biotypes in tests using
seedling wheat plants. All the lines resemble Newton but
can be up to 4 days later in heading and from 4 inches
shorter to 2.5 inches taller.
The new lines have adequate winter hardiness for grow-
ing in field trials in many areas of the United States. The
lines should prove useful for breeding Hessian fly-resistant
cultivars or for genetic studies.
Wheat breeders will use this germplasm to develop
improved wheat cultivars adapted to the eastern and south-
ern states. Seed is now available from Purdue University
and will be available in 1998 from the ARS National Small
Grains Collection in Aberdeen, Idaho.-By Hank Becker,
ARS.
Roger H. Ratcliffe is in the USDA-ARS Crop Production
and Pest Control Research Unit, Entomology Hall, Purdue
University, West Lafayette, IN 47907-1158; phone (765)
494-4606, fax (765) 494-5105, e-mail roger-
ratcliffe@entm.purdue.edu *


Agricultural Research/August 1997









Science Update


Convenience Food for Good Bugs
Liver and ground beef are two
ingredients in the recipe of a new lab
diet for mass-rearing pest-eating
insects. ARS scientists are patenting
the diet. It has been used to rear
about a dozen different insects to
adulthood. These include a native
parasitic wasp (Diapetimorpha
introita) and a predator, the spined
soldier bug. Under a cooperative
research and development agreement
(CRADA), Predation, Inc., of Ala-
chua, Florida, is evaluating the ARS
diet for rearing a native lady beetle
(Coleomegilla maculata) and two
predatory mites. ARS scientists are
refining the diet. For example, they
want soldier bugs raised on it to lay
more eggs than they do with the
current formulation. They also want
to come up with capsules-a few
millimeters in diameter-to contain
and store tiny diet servings. So, under
a different CRADA, Analytical
Research Systems, Inc., of Micano-
py, Florida, is formulating new
polymer coatings for encapsulating
the diet. One requirement: An insect
must be able to pierce the capsule to
get at the food. With an encapsulated
diet, commercial biocontrol com-
panies would have technology for
economically supplying massive
numbers of beneficial insects to
growers for use as an alternative to
chemical insecticides. Patrick D.
Greany, Center for Medical, Agricul-
tural, and Veterinary Entomology,
Gainesville, Florida, phone (352)
374-5763, e-mail
pgreany @ nervm.nerdc. ufl.edu

Keeping Cattle Cool
With cattle as with people, it's not
just the heat, it's the humidity that
often leads to daytime heat stress. An
ARS-led study of feedlot cattle
indicates the animals won't recover


from daytime heat stress if a hot or
muggy night follows. Researchers
estimate a July 1995 heat wave in the
midcentral United States cost the
cattle industry around $28 million in
animal deaths and reduced livestock
performance. But the heat wave
allowed them to take a closer look at
how temperature and humidity were
linked to the deaths. Using a Temper-
ature-Humidity Index (THI), the
scientists found strong links between
losses of vulnerable animals and three
or more successive 24-hour periods
with daytime THI scores over 83 and
nighttime scores over 74. The re-
searchers are now examining whether
feedlot cattle might benefit from
smaller feed rations for a day or two
before a predicted heat wave. Cattle
generate body heat when they digest
feed, so eating less may ease the
animals' overall heat levels. G. LeRoy
Hahn, USDA-ARS Roman L. Hruska
U.S. Meat Animal Research Center,
Clay Center, Nebraska, phone (402)
762-4271, e-mail
hahn @marcvm.marc. usda.gov

Getting Texas Farmers the Fax
on Crop Water Needs
A new weather station network
uses early-morning faxes to reach
farmers, news media, and other
subscribers in the northern Texas
High Plains. The 26-county region
annually produces over $700 million
worth of crops and $1.8 billion in
livestock and livestock products. The
network's information on plant water
needs can save farmers thousands of
dollars in water costs. Predictions
include soil water evaporation and
plant water use for irrigated crops.
They're based on hourly data from a
dozen weather stations and other
information from ARS scientists. At
least one newspaper uses the predic-
tions to help urban readers know
when to water the lawn. USDA's


Natural Resources Conservation
Service, water districts, and crop
consultants use the network to advise
farmers and others on water use and
conservation. The network is operat-
ed by the Texas Agricultural Experi-
ment Station at Amarillo. Corn and
wheat farming associations helped
build it. So did local water districts
and the Texas Agricultural Extension
Service. Farmers provide support
including land, phone lines, and
equipment for the weather stations.
The network team plans to add
information on diseases and pests. By
1999, farmers may be able to get fax
alerts about western corn rootworms
along with their morning coffee. The
network complements a similar one
in the southern Texas High Plains.
Terry Howell, USDA-ARS Water
Management Research Unit, Bush-
land, Texas, phone (806) 356-5746,
e-mail tahowell@ag.gov

Will Cotton Fiber "Muscle Up"?
Biotech cotton that grows stronger
fiber is the goal of a 5-year project of
ARS researchers and Agracetus, a
unit of Monsanto based in Middleton,
Wisconsin. ARS scientists are
evaluating some of Agracetus'
transgenic cotton plants and crossing
the most promising ones with other
varieties. New, higher speed ma-
chines that weave cotton yarn require
even stronger fiber to work best. So
higher strength fabric could give the
United States an edge in the global
textile market. And since wrinkle-
resistant, 100-percent cotton fabric
has gone through a chemical treat-
ment that can cut fiber strength up to
50 percent, starting with stronger
fiber could help reduce this weaken-
ing of the cotton's "muscles." 0.
Lloyd May, USDA-ARS Coastal
Plains Soil, Water, and Plant Re-
search Laboratory, Florence, South
Carolina, phone (803) 669-5203, e-
mail cotton@florence.ars.usda.gov


Agricultural Research/August 1997








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The Germplasm Enhance-
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A new South Africa
connection-flowers and
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consumers.


International cooperation
delivers Romosinuano cattle
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