U.S. Department of Agricullure Agricultural Research Serv ice November 2000
Well-Being of Farm
Animal well-being is a major concern
of the public, especially since the intro-
duction of intensive confinement-
keeping large numbers of livestock or
poultry in one area. The U.S. food animal
industry-with an estimated worth of
$100 billion a year-is concerned too.
But there is little scientific information
that can be used to address those
The ARS national program "Animal
Well-Being and Stress Control Systems"
is designed to fill that gap. Begun in
1994, the program's long-range goal is
to develop measures of animal well-
being to be used for evaluating and pos-
sibly improving the way farm animals
Farmers and representatives from the
beef, dairy, swine, and poultry industries
met with ARS scientists last year to help
set the program's research priorities,
which can be viewed on the World Wide
Web at http://www.nps.ars.usda.gov/
There are five ARS locations in this
program: Clay Center, Nebraska; Co-
lumbia, Missouri; Lubbock, Texas;
Mississippi State, Mississippi; and West
Lafayette, Indiana. But there are links to
numerous ARS researchers in other parts
of the United States, such as Dean M.
Anderson in Las Cruces, New Mexico
(see feature story in this issue, page 4).
Anderson's use of electronic signals to
round up cattle minimizes stress on the
cattle and their handlers. He uses satellite
signals and Global Positioning System
(GPS) receivers to locate the cows, while
electronic "turn signals" come through
microphones in special collars worn by
Anderson teaches a course in low-
stress animal management and is a
student of Temple Grandin, Burt Smith,
and Bud Williams, experts in low-stress
animal handling. Grandin recently
visited the ARS lab at Lubbock and also
participated in an ARS "Healthy Ani-
mals 2000" symposium at Beltsville,
Maryland, along with Julie Morrow-
Tesch, an ARS animal scientist at
Grandin advocates thinking, seeing,
and hearing like a cow to improve the
design of cattle facilities-the holding
lots, the various ramps, walkways, al-
leyways, and corridors livestock pass
through en route to trucks, feedlots, and
slaughterhouses. She has been known to
crawl through these passages to look for
things that might alarm animals.
Despite her unorthodox methods,
Grandin is simply encouraging operators
of farms, feedlots, and particularly
slaughterhouses to use common sense
and good husbandry practices. We want
to do our part as scientific researchers
to contribute to the efforts of people like
her, who are improving animal well-
being through a combination of research
and skilled observations.
Just as Grandin has found that some-
times a simple adjustment is all that is
needed-like tying down a chain that is
moving and rattling, bothering the
cattle -ARS researchers at Mississippi
State found they could help chicks thrive
by lowering water lines. The proper
height helps chicks coordinate their
breathing and swallowing, especially in
hot weather when they may be panting.
The chicks drink more water and don't
lose their appetite, ensuring normal
You find solutions like this only if you
take the time to observe animals in their
Morrow-Tesch doesn't use GPS to
observe cattle behavior; she uses night-
vision goggles to spot individual cattle
in densely populated feedlots. From her
mobile trailer lab parked in the feedlot,
she can observe the animals day or night
with the help of the night goggles and
special tape that reflects when struck by
invisible infrared light. The cattle can't
see her, and they're accustomed to the
trailer, so they continue their natural
She also places video cameras in
commercial feedlots to record animal
behavior. In one such project, 24-hour-
a-day observation of cattle showed that
switching their standard morning feeding
time to sunset reduced aggressive be-
haviors by almost half. In dry weather,
the pushing and shoving that occurs
among cattle stirs up dust. The slashing
of aggressive behaviors brought dust
levels well below allowable limits.
Jack Nienaber, of Clay Center, also
films livestock behavior. And he uses
automated weighing feeders to record
how much feed livestock eat, and
automated sensors to monitor livestock
temperature and heart and respiration
rates. This data reveals the thermal stress
level of livestock and will be useful in
managing cattle in feedlots.
In West Lafayette, ARS scientists are
observing responses of different genetic
lines of swine to handling and transport
to market. They are correlating behavior
with physiological measurements, which
could lead to an objective measure of
In Columbia, ARS researchers are
studying how appetite stimulants help
pigs cope with stress during the fragile
neonatal period. Also, new dietary
supplements have been found to help
piglets fight disease and other stresses.
Improving survival by one piglet per litter
is worth about $400 million a year for
the swine industry.
Lewis W. Smith
ARS National Program Leader
Agricultural Research/November 2000
Vol. 48, No. 11
Agricultural Research is published monthly by the
Agricultural Research Service, U.S. Department
of Agriculture (USDA). The Secretary of
Agriculture has determined that this periodical is
necessary in the transaction of public business
required by law.
Dan Glickman, Secretary
U.S. Department of Agriculture
I. Miley Gonzalez, Under Secretary
Research, Education, and Economics
Floyd P. Horn, Administrator
Agricultural Research Service
SaiJ\ Millrer Hai, i Director
Infi irmjiir- Sriwff
Edlior. Roheri So% ers
As.,ticiale Editor: Nue Kendal]
A\r DireLtor \ illia.m Iohrnon
Phioto Ediior A-\rta Dajme!
Staff Phoiograplher.- Scott Bauer
Information in this magazine is public property and
may be reprinted without permission. Non-
copyrighted photos are available to mass media in
color Lran.parencie. Order by photo number and
date of magazine issue.
A. ,, ,l,/r,, Re .tLc/ magazine articles and
photographs are posted on the World Wide Web
monthly at http://www.ars.usda.gov/is/AR/.
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Orders, Superintendent of Documents, P.O. Box
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The Cyber Cow Whisperer and His Virtual Fence 4
Fabric To Dye For 8
Faster Detection of Plum Pox Virus 10
Sunflower Scientists Keep Looking Ahead 11
New Fungal Strain Spells Trouble for Caterpillar
Whitewashing Agriculture 14
New Products To Suppress an Old Insect Pest 18
Learning To Live with Japanese Brome 20
Lactic Acid Reduces Microbes in Poultry 20
The Cause of Bronze Wilt of Cotton 21
Promising New Mastitis Vaccine 22
Science Update 23
Cover: Posts and barbed wire are part of the scenery on most ranches. But satellite
technology is making it possible to guide animals over rangeland with electronically
generated cues rather than traditional fences and cattle drives. Photo by Scott Bauer.
In the next issue!
" TERRIFIC TUBERS-Tired of the same old spuds? ARS plant
breeders have developed several new high-yield, disease-resistant
varieties that are giving established ones some stiff competition.
(* WONDERING WHEN TO WATER? In Texas, a network of weather
stations takes the guesswork out of irrigation by faxing farmers daily
water-use information. The goal: A secure future for a major water
source, the Ogallala Aquifer.
(0 LEAF-SURFACE ECOLOGY-What really happens to a plant after
it's sprayed with a pesticide? By using the latest scanning electron
microscopes, scientists can magnify a leaf hundreds of thousands of
times and observe a world they've never seen before.
Agricultural Research/November 2000
Sky Rider, but he's really a
Cyber Cow Whisperer.
His colleagues call him Sky
Rider because he rounds up
cattle with the help of Global Positioning
System (GPS) signals coming from
But his prototype locator/controller
cow collar also whispers electronic ver-
sions of the cowboy's "gee" (go right)
and "haw" (go left) into the cow's ears.
By controlling movement, the whispered
commands act as a virtual fence.
"Cows can seem ornery if they don't
do what we want them to do," says
Anderson, anARS animal scientist in Las
Cruces, New Mexico. "After all, they still
have some wildness in them from their
prehistoric ancestors, aurochs." These
wild oxen once roamed Earth freely.
They stood 6 feet tall and were the sub-
ject of many a cave painting, along with
wooly mammoths and bison.
Anderson is a longtime student of
using cattle's innate behaviors to manage
them in a kinder, more effective, and
gentler way. He has automated the
husbandry principles of better-known
practitioners of low-stress animal
management, such as Bud Williams, Burt
Smith, Temple Grandin, and Buck
Brannaman, the real Horse Whisperer,
played by Robert Redford in a movie of
the same name.
Anderson also teaches low-stress ani-
mal-handling concepts, such as how to
control cows by invading and retreating
from their personal space.
"You can make a cow move in differ-
ent directions depending on where you
stand, or by the direction, angle, and
speed of your approach," he says. "The
virtual fence uses electronically gener-
ated cues instead of a person to achieve
the same effect."
Hands-Off Cattle Drivers
Anderson oversees his "sky-riding"
research from a pickup truck. He gives
the cows their marching orders with a
On the 300-square-mile Jornada Experimental Range near Las Cruces, New Mexico,
technicians Rob Dunlap (left) and John Smith round up cattle the time-honored way.
High-tech equipment may make roundups easier in the future.
manually operated signal transmitter,
which looks like a remote control for toy
airplanes and cars. Anderson says man-
ual control is necessary in the research-
and-development phase, but eventually
his virtual fence will be completely au-
tomatic, with all signals coming from
satellites. Ranchers will be free to have
their morning coffee while they check
their computers to see their cows' move-
ments over the past few days and then
program future meanderings.
Anderson says that the patented inven-
tion won't replace resource managers or
the cowboys who ride the range, but it
will help them accomplish their goals by
working on "animal time."
"Animal time is preferable to human
clocks when managing cows and their
behaviors. This reduces stress for both
the cowboys and the cows."
Traditionally, cowboys and ranchers
rise before the cows and then wake the
cows up to move them to another pas-
ture. Balky cows often stand stubbornly
between the ranchers and a second cup
of coffee, not to mention the rest of their
busy schedules. If the electronic whis-
per is used correctly, it can lower the
stress of these cattle roundups.
Anderson explains: "It is desirable to
administer the sound cues when the an-
imal is moving. As a foraging animal ap-
proaches a virtual fence line and passes
a programmed point, it activates sound
cues to the animal's right or left side.
Software in the device mathematically
determines to which side the cues should
be applied, based on the animal's angle
of approach to the virtual fence line.
Since animals tend to move away from
startling sounds, if we want the animal
to move left, we'd give the cues to the
right side, and vice versa."
Agricultural Research/November 2000
. -IM ^ B *^ --k *t **
A prototype cow collar whispers electronic versions of the cowboy's
"gee" (go right) and "haw" (go left) into the cow's ears. By controlling
the cow's movement, the whispered commands act as a virtual fence.
,.- -!-1.- --- a.L
a.- -I ~ ij s5~~
First, Get Their Attention
The initial sound cues are soft,
although they can get louder if the animal
continues to move without changing
direction. At another predetermined
point, a mild electrical shock-also
capable of increasing in intensity, if
needed-is applied from a battery on the
collar to reinforce the sound. The shock
is the same as that given off by electronic
collars used to train dogs or keep them
within safe boundaries. It's designed to
get the animal's attention without
inflicting physical harm. Preliminary
research indicates it's seldom necessary
to use the electric shock, or even raise
the decibels, once cows learn the con-
sequences of not responding appro-
priately. It takes only a few times for them
to learn the correct response.
"If a cow's too stubborn to go the way
we want it to go, even after a full set of
Agricultural Research/November 2000
sound and shock treatments, we leave it
alone so we don't put unwarranted stress
on it," Anderson says. "Remember, we're
manipulating animal behavior, and a one-
size-fits-all approach is simply not
He plans to attach heart monitors to
some cows before proceeding much fur-
ther, to quantitatively document the
physiological impact the cues have on
"I don't think it stresses the animals
unduly because many times I've seen
them resume grazing shortly after being
startled by a signal. The only difference
is that afterward they're facing the de-
sired direction," Anderson says.
Livestock Can Shape Landscapes
So why move a cow at all? One reason
is to provide animals with enough high-
quality forage to meet their nutritional
"Improved testing technologies allow
us to determine-in minutes rather than
days-exactly what the animal has been
eating. This information allows us to re-
spond immediately in managing their
needs, and the virtual fence can rapidly
guide the animals to new areas of for-
age." Anderson says.
Furthermore, few land managers
would dispute the pivotal role animal
distribution plays in shaping landscapes.
Past overgrazing certainly played a part
in desert landscapes around the world.
Anderson and his cows operate on a
range station established 88 years ago in
the vast Chihuahuan Desert. In 1912,
about 190,000 acres of semidesert range-
land in southern New Mexico were
withdrawn from public use to form the
Jornada Experimental Range. Sprawling
between the San Andreas Mountains to
the east and the Rio Grande Valley to the
west, this research ranch is one-fourth the
size of Rhode Island and is ARS' largest
Since the Jornada's beginning, animal
scientists have worked to establish
principles for proper grazing manage-
ment by trying various tools to distribute
cattle evenly over large pastures.
Separating water troughs from salt
blocks helped lure them to different areas
but has never been fully successful.
"There are few, if any, simple answers
when it comes to managing animals,"
Anderson says. "Fences are the only sure
way to rotate cattle grazing areas, but
they're not always practical here in the
arid Southwest, where a cow may have
to graze more than 640 acres to get
enough grass in a year."
Early in his research career, Ander-
son experimentally evaluated rotational
stocking, in which large numbers of cat-
tle were moved through a series of rela-
tively small paddocks at short intervals
to prevent overgrazing. This procedure
had merit; but conventional fencing
costs, even electric fences or suspension
fences with widely spaced posts, made
it an economically questionable practice
outside the research arena.
For the first time, virtual fencing of-
fers a tool to improve foraging through
manipulating animal distribution and
stocking density in a flexible and rapid
manner without the need for continuous
human presence or ground-based wire
"It is obvious how excluding animals
from areas with poisonous plants or
sensitive landscapes-such as stream
areas-could be accomplished using this
device; however, it may be less obvious
how animal density can be managed,"
Anderson says. Virtual fence lines do not
have to enclose just acreage; they can
be programmed to surround individual
animals. Group dispersion can be
managed by deciding how close together
individual animals should be during
foraging or other activities.
Origin of the Concept
The idea of a virtual fence for cows
came to Anderson when he was a gradu-
ate student in the mid-1970s-long be-
fore current technology was available.
"On Highway 6, just north of Waco,
1 Craig Hale (left), of Future
Segue. and animal scientist Dean
Anderson examine the prototype
virtual fence device they invented.
Audio cues generated from the
device tell the cattle which way to
2 Technician Roy Libeau left) and
Anderson place a neck saddle
containing the prototype virtual
fence system on a cow. (K9102-7i
3 The prototype virtual fence
device is shown here as a neck
saddle. Future versions ma. be
reduced to the size of an ear tag
or smaller. (K9102-9)
4 Cattle and sheep grazing together
in a "*lerd." The animals are
bonded socially, so they remain
5 Gary Rayson (left), an associate
professor at New Mexico State
University, and Anderson use
luorometry to rapidly determine
diet composition of free-ranging
6 Postdoctoral research associate
Mary Lucero and animal scientist
Rick Estell evaluate plant-extract
data from diets of cattle. (K9101-20)
Photos by Scott Bauer
Texas, my graduate adviser and I were
driving and talking when a small paddock
came into view. There, with outstretched
necks, leaning against a fence that no
longer stood upright, was a menagerie of
livestock, all attempting to secure that last
blade of green grass just out of reach. My
professor commented: 'That is what
fences were not designed to do,'"
"I thought, That's right. If you manage
cattle correctly so they have enough
nutritious plants to eat all the time, you
should be able to manage them with a
fence that's as invisible as radio waves."
Intermingled Species Graze Safely
Anderson and colleagues have used
electric fences on the Jornada to protect
sheep from predators. To help eliminate
the use of the costly fences, Anderson
again turned to innate animal behaviors
as management tools. Cattle and sheep
won't always stay together if stocked on
the same pasture. But if a bond between
the two species is formed, the sheep will
consistently stay close to the cattle in a
configuration termed a "flerd."
Anderson and Clarence V. Hulet, a re-
tired ARS animal scientist, raised lambs
with young heifers for 30 to 60 days to
get them to bond to cattle. The cattle drive
off coyotes and stray dogs.
There is another benefit to inter-
mingling cattle, sheep, and even goats:
Bonded livestock species spread them-
selves more evenly over the pasture
during foraging, compared to animals that
have not bonded. Furthermore, sheep tend
to eat plants passed over by cattle, so more
animals could potentially be raised per
acre. Anderson and colleagues found that
adding two sheep per cow did not damage
the range during years with average to
above average precipitation. With virtual
fencing, sheep and goats could experience
the same freedom as the instrumented
cows they follow.
Who's the Boss?
"With virtual fencing," says Anderson,
"I'm again trying to capitalize on innate
animal behavior. I will accomplish my
management goals, but on their schedule.
It's like doing a job the way you know it
should be done, but letting your bosses
feel like it was all their idea.
"For example, after a cow has been in
a corral for a drink of water, with a few
subtle cues as she leaves the corral it
should be possible to move her to a new
area to graze. A fundamental law of phys-
ics is that it's easier to move a body that's
already in motion than to start one mov-
ing from a dead stop," Anderson says.
"If you let the animals think they're
winning and still accomplish your goals,
you have a win-win situation-and you
don't need a 'Berlin Wall' to hold them
in. My career has focused on the efficient
and humane treatment of animals-from
rotational grazing, to weighing animals
as they pass through gates to a water
trough in a pasture without having to
gather them in a barn for manual weigh-
ing, to the virtual fence, which allows the
animal to move freely but under guidance
based on sound ecological practices."
Anderson credits USDA's Natural
Resources Conservation Service, Grazing
Lands Technology Institute, for providing
financial support for his research.
It's Economical, Too
For large areas of the world, conven-
tional fencing is just not economical, yet
animal control is desperately needed to
prevent improper resource use.
"Half of the cost of fencing is in the
labor, which would go sky-high if you
fence high mountain pastures," says
Anderson. But with virtual fencing, "you
no longer have to fence for human
convenience. Virtual fences can go
wherever the ecology dictates the cow
needs to go. In the past, we've always
placed fences based on accessibility-
whether by vehicle, horse, donkey, or on
foot. Human convenience has always won
out, not any theory of range management.
But that's not always best for the range
or the cow."
Anderson believes that technological
advances will eventually make the virtual
fence more affordable. "In the future it
may be possible to instrument individual
animals for only a few dollars apiece,"
he says. "Data I collected in 1998 sug-
gested that conventional fencing costs
from $1,200 to $14,000 per mile for
materials and installation."
But Anderson thinks cost won't be as
big a barrier to adopting virtual fencing
as the ability to think differently about
cattle management. Since cows follow
leaders, and bonded sheep and goats fol-
low cows, Anderson envisions needing
the virtual fence device only on the lead-
ers. He plans research to find out how and
if he can identify the characteristics of
leaders among range animals.
"The leaders on the range may not
have the same motivation to lead as the
animals that are always first to enter the
milking parlor," he says.
Anderson makes it clear he isn't
advocating an end to conventional fences.
"Fences that mark property boundaries
or protect the health and safety of people
or livestock should not be replaced with
virtual fences," he says. "But for manage-
ment of vast acreages, eliminating
internal fences may be ecologically and
"The cow won't do the job like a 9-to-
5 employee, or even a 4 a.m- to-10 p.m.
rancher," Anderson says, "but the cow
will do the job-with a little help from
21st century technology."-By Don
This research is part of Rangeland,
Pasture, and Forages, an ARS National
Program (#205) described on the World
Wide Web at http://www.nps.ars.usda.
Dean M. Anderson is with the USDA-
ARS Southern Plains Area Range Man-
agement Research Unit, P.O. Box 30003,
Las Cruces, NM 88003-0003; phone
(505) 646-5190, fax (505) 646-5889,
e-mail email@example.com. *
Agricultural Research/November 2000
ut .,A.4- t Z6.'f.<"
6 [4 11I
%iViotton ma\ soon be afforded the same upscale
recognition as wool, thanks to ine\' technology ARS chemists
Jeanette NM. Cardamone and William N. Nlarmer have found a
\way to make cotton more chemnicall similar to its high-end
counterpart-\ ool-so that a fabric blend of the two can be
Dveine a cotton/i ool blend is difficult because the two fibers
hae dillerent chemical makeups,. Wool. w which is sheep hair,
is made of animal proteins. while cotton is made of plant
cellulose-the main part of a plant's cell \ all. Nonnally, when
\ ool and cotton are blended together. t\o separate dye baths
are required because the wool takes up most of the dye.
"The process we developed is a ne~ single-bath dyeing pro-
cedure called union dyeing," sa s Cardamone. She and Marmer
are with the Hides. Lipids. and Wool Research Unit at ARS'
Eastern Regional Research Center IERRCi. in Wyndmoor,
Pennsl\ ania. "This process helps textile manufacturers over-
come a major technological barrier: dyeing all-natural blends
to the same depth of shade in one step.
In the con national procedure. Cardamone explains, cotton
is dyed first and \ool second Wool is dyed in an acidic
environment at high temperatures, and cotton is dyed in a
nonacidic en\ ironment at lower temperatures. This difference
requires that the w\ool and cotton be dyed either separately, or
sequentially in one bath in \ which the pH and temperature levels
"Our improved method uses pretreatments to make the
cotton as receptive to dye uptake as the w\ool," she says.
Cardamone and Nlarnmer's simple approach is to reverse the
chemical charge of cotton from negative to positive before
I... ... H v.,r. ,, i1, dyeing. w ool is already positive. To do
this, they use cationic fixatives-
positl\el) charged ions-which are
typically used after cotton is dyed to
help it keep its color. Applying the
fixatives before d being gt\ es both fiber
components of the fabric a positive
y charge Since the d\e is negatively
charged-and opposites attract-the
S cotton and \\ool e to a uniform shade
because the dye is attracted equally to
both fibers. This union-di being process
use. one dye ill one bath, under one
set of conditions.
Cotton industry officials are excited
about the new process. "This tech-
Technician Chet Sutton nology is easy to adopt," says John
studies colorfastness of
a studies colorfastness of on-dyed wooTurner, a senior chemist with Cotton
a union-dyed woo Incorporated in Cary, North Carolina.
cotton blend. Incorporated in Cary, North Carolina.
Agricultural Research/November 2000
"It doesn't require elaborate equipment or expense. In the past,
there was no satisfactory method for cotton mills to dye blends.
This technology could potentially increase the use of cotton."
Cotton Incorporated wants to expand the use of cotton and make
it more profitable for cotton farmers and the textile industry.
PEGGY GREB (K9137-3) "This process gives cot-
ton an upscale market. A
cotton/wool blend would
have greater value than a
100-percent cotton item,"
Turner says. "And depend-
ing on the blend level, it
could be cleaned in the
washing machine." Cotton
Incorporated has a research
partnership with the ERRC
w The wool industry also
f finds the concept appealing
b because it creates a new mar-
ket for wool. Approximately
"c g to c because it creates a new mar-
66,800 sheep producers raise
7.2 million sheep and lambs,
producing about 49.2 mil-
lion pounds of wool in the
United States. Even so, the
country still imports wool
Chemists Jeanette Cardamone from Australia and New
and William Marmer study
records of the effect of dyeing Zealand. This technology
regimen on dye uptake. could help open more mar-
kets for American wool by
Keeping Colors Colorful
The ERRC scientists also use another method that helps
make dyeing wool/cotton blends possible-a durable-press
finishing resin. The resin treatment was originally developed
by chemists at the ARS Southern Regional Research Center
(SRRC) in New Orleans, Louisiana, to prevent wrinkling in
100-percent cotton. SRRC scientists further developed the
technology to increase cotton's dyeability. SRRC chemist
Eugene Blanchard collaborated with ERRC scientists on using
the durable-press finishing resin treatment for cotton/wool
Cardamone says resin treatments, which are alternatives to
cationic fixatives, are important for good colorfastness in
laundering. Colorfastness is a textile industry standard that
determines how stable the color is in a garment. Good
colorfastness means the garment won't fade after one washing.
Resin pretreatment is best for garments that require excellent
colorfastness. Cationic fixatives could be used for outerwear
garments where colorfastness to washing is moderate but
colorfastness to dry cleaning is high, notes Cardamone.
"Both pretreatment systems will effectively lead to union-
dyeing of wool/cotton blends, but the treatment should be
selected to accommodate the anticipated end use. A wool/
cotton-blend fabric is ideal for multiseason apparel because
wool provides inherent resiliency and warmth while cotton
contributes comfort and coolness," says Cardamone. "These
experimental textile treatments may broaden the market for
cool-weather garments made of cotton/wool blends. In
sweaters, for example, the blend's wool component retains
body heat and imparts thickness, while cotton makes it
comfortable to wear. Both natural fibers are great at wicking
away moisture, too."
Through a cooperative research and development agreement
between ERRC researchers and chemical specialties
manufacturer Hercules, Incorporated, other pretreatment
systems are being investigated.
Applied commercially, these technologies may cut textile
dyeing costs-savings that can be passed on to consumers
seeking versatile garments for spring and fall.-By Tara
This research is part of New Uses, Quality, and Market-
ability of Plant and Animal Products, an ARS National
Program (#306) described on the World Wide Web at http://
William N. Marmer and Jeanette M. Cardamone are with
the USDA-ARS Eastern Regional Research Center, Hides, Lip-
ids, and Wool Research Unit, 600 East Mermaid Lane, Wynd-
moor, PA 19038; phone (215) 233- 6585 [Marmer], (215) 233-
6680 [Cardamone], fax (215) 233-6795, e-mail wmarmer@
arserrc.gov firstname.lastname@example.org. *
Technician Kimberly Baxendale dyes samples of a wool/cotton
Agricultural Research/November 2000
Faster Dtedition of
Plum Pox Virus
S scientists with the Agricultural
Research Service have devel-
oped techniques that not only
confirm the presence of plum
pox virus (PPV), but also identify its se-
vere and less virulent strains.
PPV infects stone fruits, such as
plums, apricots, peaches, and nectarines,
as well as almonds. It produces blem-
ished, misshapen fruit and can cause fruit
to drop prematurely from
the tree. It can even keep JOHN HAMMOND (K91
a tree from bearing any
fruit at all.
Determining the ori-
gin of plum pox virus is
a critical step in eradicat-
ing this emerging disease
that now threatens the
$1.3 billion U.S. stone
fruit industry. The chal-
lenge lies in being able
to distinguish different
serotypes, or strains, of
the virus. This knowl-
edge can help research- Symptoms of p
ers determine the se-
verity of infection on
different tree species and
provide clues to its origin
and mode of transmission.
While stone fruits have been in the
United States for centuries, PPV has not.
It was first detected in 1999 on peaches
grown in Adams County, Pennsylvania.
Before that, it was not known to occur
in North America at all. Therefore, any
PPV infestation represents a major threat
to everyone involved in stone fruit pro-
ARS researchers in the Floral and
Nursery Plants Research Unit at the U.S.
National Arboretum in Washington,
D.C., led by plant pathologist John
Hammond, and working with colleagues
at the University of Agriculture in
Vienna, Austria, have developed a new
way to detect and identify the virus by
using a technique called polymerase
chain reaction (PCR).
"Previously available serological
methods sometimes lack sensitivity of
detection or strain specificity," says
Hammond. "And biological testing by
grafting onto indicator species is slow
and cannot differentiate PPV strains by
serotype." PCR, on the other hand, is
faster and far more specific.
PCR exponentially multiplies the
target molecules in the virus' nucleic
ilum pox virus on apricot fruit and leaves.
acid, making enough DNA copies to be
analyzed. ARS researchers and their
Austrian colleagues have developed PCR
primers that initiate this DNA replication.
The results enable the detection of all
PPV strains in a sample.
The scientists then combined PCR
with a method called restriction fragment
length polymorphism. This technique
uses special enzymes to identify DNA
fragments unique to each strain. The
variation in the size of these fragments
helps researchers differentiate strains of
"The ability to distinguish between
different isolates of the same serogroup
is important because it allows us to track
the origin of an infection," says
Hammond. "For example, if an orchard
is found to be infected, the source might
be the mother trees used for propagation,
aphids from a neighboring orchard, or
weed hosts of the virus."
Distinguishing PPV serotypes may
also help researchers correlate a par-
ticular strain with its ability to infect a
specific type of host plant. Some strains
of PPV may infect a tree easily, while
others can do so only with great
Other researchers have developed
PCR methods that can differentiate some
PPV serotypes but not isolates within a
single serotype, Hammond says.
"The distinction may indicate that the
tree has been infected for a long time and
that variants have begun to appear. Or it
could be that the tree has been infected
on multiple occasions and from differ-
ent sources," says Hammond. This
knowledge is key to checking the spread
of the disease and eradicating it from
infected areas.-By Jesds Garcia, ARS.
This research is part of Plant Diseas-
es, an ARS National Program (#303)
described on the World Wide Web at
http://www. nps. ars. usda.gov.
John Hammond is in the USDA-ARS
Floral and Nursery Plants Research
Unit, Building 010A, Room 242, Belts-
ville, MD 20705; phone (301) 504-5313,
fax (301) 504-5096, e-mail jhammond@
Agricultural Research/November 2000
PEGGY GREB (K9116-1) resistance and
o of other mildew races,
Gulya and coworkers
Not "er located new sources of
S i mildew resistance and
ist transferred the genes into
agronomically acceptable germplasm.
o, he Now, new sunflower hybrids with USDA-bred
resistance, combined with fungicides, may avert
The fungus Sclerotinia causes sunflower diseases that
account for half of the disease-related yield losses in the
Northern Great Plains. In some years these losses total $15
million. Sclerotinia stalk rot, the most significant sunflower
gricultural Research Service sunflower scien disease in the United States, appears year in, year out, regardless
tists, ever vigilant for new pathogen strains of weather.
(causes of disease) that can threaten commercial With neither chemical-control nor genetic-resistance
sunflower crops, have a successful track record weapons, the U.S. grower is nearly defenseless. ARS scientists
in countering them through plant breeding. In have been searching for tolerance to the disease, both in
their continuing endeavor, these researchers and their cultivated breeding lines and in wild sunflowers, for the past
international colleagues currently focus mainly on three major two decades. Recent germplasm releases by the ARS team have
diseases: Sclerotinia stalk rot and head rot and downy mildew. given the sunflower industry its first sources of tolerance to
"To develop new sunflower breeding lines with disease Sclerotinia stalk rot.
resistance, we rely heavily on genetic resources from wild Sclerotinia head rot occurs during wetter-than-normal
sunflowers that evolved in their native North PEGGY GREB (K9119-1) growing seasons-like September 1999.
America," says ARS plant pathologist More than 75 percent of the sunflower
Thomas J. Gulya, of the Red River Valley acreage in North Dakota had head rot, which
Agricultural Research Center in Fargo, not only caused substantial yield losses, but
North Dakota. also contaminated the soil for many years.
The North Central Regional Plant Intro- Whenever soil is highly contaminated with
duction Station-a joint venture among sclerotia, growers must rotate to a crop like
ARS, 12 agricultural experiment stations, wheat, which is prone to scab, instead of to
and Iowa State University, in Ames-now other Sclerotinia-susceptible broadleaf
provides a reservoir of 1,600 cultivated sun- crops, such a soybeans, dry beans, or
flower accessions (specimens) and more canola. ARS scientists had already been
than 2,200 accessions of the 49 wild sun- working with researchers in Argentina and
flowerworking with researchers in Argentina and
flower species from which scientists may o France to find sources of resistance to head
draw for breeding experiments or research rot, but after the 1999 epidemic, head rot
rot, but after the 1999 epidemic, head rot
purposes. l research became a much higher priority.-
Scientists like Gulya are typically unsung By Ben Hardin, ARS.
heroes. As diseases are controlled, the low This research is part of Plant Diseases,
incidence of epidemics tends to go un- an ARS National Program (#303) described
noticed. For example, some 15 years ago, a ;.A on the World Wide Web at http://www.nps.
single registered fungicide was so effective
Plant pathologist Thomas Gulya ars. usda.gov.
compares a sunflower seedling Thomas J. Gulya is with the USDA-ARS
mercial plant breeders did not include showing typical symptoms of downy Northern Crop Science Laboratory, Red Riv-
mildew resistance among their top breeding mildew (left) with a healthy seedling er Valley Agricultural Research Center P.O.
priorities. During the past 2 years, however, protected by a new fungicide. Box 5677, University Station, Fargo, ND
ARS scientists at Fargo have found new 58105; phone (701) 239-1316, fax (701) 239-1346, e-mail
fungicide-resistant strains of downy mildew. Anticipating email@example.com. *
Agricultural Research/November 2000
New Fungal Strain Spells Trouble for
T he future of environmentally
friendly crop insecticides could
be brightened by the discovery
of a more effective fungus from
which to make mycoinsecti-
cides. Mycoinsecticides are fungal
sprays that work on insect pests from the
inside out. Fungal spores attach to an
insect's cuticle, germinate, and then
penetrate its body. Spores from dead
A public-private venture survive to
has found a new, highly infect later
virulent fungal strain that pest gen-
kills a broad range of cat- erations.
erpillar pests. A new
the Beauveria bassiana fungus known
as BB-1200 appears to be even more
effective in curbing lepidopteran-or
caterpillar-pests than its close relative,
the commercially available GHA strain.
In laboratory bioassays, BB-1200
consistently exhibited virulence equal to
or greater than the GHA strain against
all lepidopteran pests tested, including
fall armyworm, beet armyworm, black
cutworm, corn borer, and cabbage loop-
er-pests that are not highly suscepti-
ble to the GHA strain, according to ARS
ecologist Stephen P. Wraight.
"These lepidopteran defoliators are
among the most destructive insect pests
of important crops like corn and cabbage
and other vegetables. Each year, they
cause billions of dollars in losses," says
ARS entomologist John D. Vandenberg.
Cooperation Leads to Success
While the GHA strain of B. bassiana
is effective against some lepidopteran
pests-including diamondback moth-
in the field, vegetable crop damage typ-
ically results from the feeding activities
of several caterpillar pest species.
Manufacturers of conventional pesti-
cides, however, are often reluctant to
research new controls for these pests
because their hosts are considered to be
minor crops and therefore offer limited
It was through a cooperative research
and development agreement between
ARS and Mycotech Corporation of
Butte, Montana, that spores of Beauveria
strain GHA came to be incorporated in
two commercial biocontrol products:
Mycotrol and BotaniGard. These
products grew out of joint efforts to
exploit a Beauveria strain first dis-
covered by Vandenberg over two decades
Now with ARS at the U.S. Plant, Soil,
and Nutrition Laboratory at Ithaca, New
York, Vandenberg collected the GHA
strain while he was a graduate student at
Oregon State University-Corvallis in
1977. Originally isolated from a chry-
somelid beetle, the GHA strain was test-
ed extensively against grasshoppers and
whiteflies before its commercial devel-
opment and patenting by Mycotech.
The commercial products Mycotrol
and BotaniGard are registered for use in
the United States, Mexico, and other
countries for biological control of grass-
hoppers, whiteflies, aphids, thrips, and
diamondback moths. They can be used
on many important agricultural crops,
such as cabbage, broccoli, cucumbers,
and greenhouse ornamentals.
"The fungus used in the Mycotrol and
BotaniGard products could be said to
originate here at Ithaca," says Wraight.
That's because Mycotech scientists
discovered the commercial pest-control
potential of the GHA strain after
screening many other strains selected
from the ARS Collection of Entomo-
pathogenic Fungal Cultures (ARSEF) in
Ithaca. The GHA strain originated from
Vandenberg's culture, originally depos-
ited as ARSEF-201.
Curated by ARS microbiologist
Richard A. Humber, the Ithaca collection
includes about 6,200 cultures of fungi.
Specimens are stored at very low
temperatures in liquid nitrogen, and
many have undiscovered insect bio-
control properties, Humber says.
The Search for a Better Fungus
"After the discovery of ARSEF-201,
the search intensified for a more highly
virulent, broad-spectrum mycoinsecti-
cide effective against a large group of
lepidopteran pests," says Wraight.
Since the registration of Mycotrol in
1995, its use in the United States has been
largely limited to greenhouse production.
Larger markets have been slow to devel-
op, but vegetable production is one area
in which demand for mycoinsecticides
is strong. That's partly because of recent
passage of the Food Quality Protection
Act, which regulates insecticide use on
certain food crops.
During 1998 and early 1999, ARS
scientists at Ithaca tested about 50 strains
of B. bassiana and several of Paecil-
omycesfumosoroseus-selected from the
extensive culture collections of ARS and
Mycotech-against the diamondback
moth, fall armyworm, European corn
borer, and corn earworm. They also
tested promising strains against the beet
Uarmyworm,. blk cutI or ni. cabhhba.ge
looper, and imported cobbajge orn
"Man, of the c strain cmIe from the
ARSEF collection, which is veritable
A healthy armyworm (right) next to two treasure trove of untapped potential bio-
that were killed and overgrown by
B. bassiana strain Mycotech BB-1200. control fungi," says Wraight. "But we
found no single strain with acceptable
mass-production characteristics that was
KEITH WELLER (K9124-2) also highly virulent against more than
three pest species."
Entomologist John Vandenberg examines a
culture of BB-1200, discovered to be highly
virulent against a broad range of
Better Than the Rest
Then, in June 1999, Wraight and
Vandenberg, who head up the ARS
fungal-screening program at Ithaca,
discovered the high virulence and
exceptionally broad lepidopteran host
range of the BB-1200 strain.
"Mycotech had received this new
isolate-originally taken from a
diamondback moth-from a collaborator
and passed it on to the ARS fungal-
screening program for routine study as
part of our long-standing cooperative
agreement," says Wraight.
Laboratory testing of the BB-1200
strain is continuing at Ithaca, to further
characterize its host range and virulence
and to determine its potential for use as a
biological control agent in the United
States, says Wraight. Field and green-
house experiments are planned that will
compare effectiveness of exposing moths
either to direct sprays of fungal spores or
to spores sprayed on plant foliage.
Meanwhile, researchers at Mycotech
are investigating industrial-scale mass
production and shelf life of the new fun-
gal strain. Other Mycotech collaborators
are assessing its efficacy against thrips,
whiteflies, and other major insect pests.
Mycotech has applied to the appro-
priate regulatory agencies to request
permits for limited field testing in the
United States. Preliminary field evalua-
tions against armyworms and diamond-
back moths are under way in Mexico and
Guatemala. Results of these studies will
determine whether further commercial
development is warranted.
The Ithaca lab's role in future de-
velopment efforts will focus both on field
testing of new BB- 1200 formulations and
on laboratory studies to discover reasons
for BB-1200's high level of potency
against lepidopteran pests. If successful,
this collaboration could lead to regis-
tration, production, and use of one or
more new mycoinsecticides to control
lepidopteran pests and better protect the
nation's vegetable crops.-By Hank
This research is part of Plant, Micro-
bial, and Insect Genetic Resources, Ge-
nomics, and Genetic Improvement, an
ARS National Program (#301) described
on the World Wide Web at http://
www.nps. ars. usda. gov.
Stephen P. Wraight, John D. Vanden-
berg, and Richard A. Humber are with
the USDA-ARS U.S. Plant, Soil, and Nu-
trition Laboratory, Tower Rd., Ithaca, NY
14853; phone (607) 255-2458, fax (607)
255-1132, e-mail firstname.lastname@example.org
jdv3 @ cornell. edu/rah3 @ cornell. edu. *
Agricultural Research/November 2000 Agricultural Research/November 2000
An Empire apple protected with a kaolin coating (left) and another one treated with conventional pesticides (right).
of his hand ... and he was far from New York City.
In the orchards of ARS' Appalachian Fruit Research
Station in Kearneysville, West Virginia, the severe
drought of 1999 revealed another advantage of covering
apple and pear trees with a white, reflective film of specially
processed kaolin, a type of clay. Empire apples harvested from
treated trees were an average of 17 percent larger than fruit
from trees left naked to withstand the heat-even from trees
that were irrigated. And there was no decline in the number of
Sekel pears reacted a little differently. The protected trees
yielded twice as many pears as the naked trees-with no loss
in fruit size, says Glenn, a soil scientist and plant physiologist.
On the West Coast, the stark-white particle film, now sold
under the trade name Surround WP, prevents sunburn on ap-
ples and walnuts, he adds.
Yes, fruit can suffer sunburn too, and the damaged areas are
perfect places for rot organisms to multiply. So packers pay
bottom dollar for produce with blemished skin or shells, or
they reject it altogether. In studies here and in South America,
South Africa, Australia, and New Zealand "the kaolin-based
product has cut sunburn damage on apples in half," Glenn says.
That reduction gives growers an economic advantage, says
Jim McFerson, manager of the Washington Tree Fruit Research
Commission. He notes that
several Washington apple
growers are using kaolin to
prevent sunburn alone. In his Minepal COatlig Col
collaborative studies with
Glenn, the coating has not increased tree vigor or yield nor
improved the color of the state's apples as it has in the East.
As nomads crossing the desert wear white robes to reflect
the sun's rays, trees wearing the specially processed kaolin
coat reflect the heat-producing infrared wavelengths, as well
as the burning ultraviolet rays. In fact, it's the ability to keep
the tree cooler under a blazing sun that increases yield.
"The reflective kaolin helps to improve the tree's environ-
ment by reducing leaf temperature and heat stress," explains
Glenn. As a result, the leaves keep their tiny portals-sto-
mates-open, allowing more carbon dioxide to enter. This
gives the leaves more raw material to photosynthesize into
food for the tree.
"The tree doesn't have to abort as much fruit, and there's
more carbon for its own growth and maintenance," explains
Glenn. The result: a healthier, happier tree that can support
higher yields year after year.
In the Kearneysville orchards last summer, kaolin-coated
trees photosynthesized up to 30 percent faster than uncoated
trees, says Glenn. He measures the rate of photosynthesis by
covering the whole tree with a clear balloon through which he
forces air with a fan. His instruments read how much carbon
dioxide enters the balloon at the bottom and how much exits
the top. The difference is a
measure of photosynthesis.
A multiyear drought
ldCut Cei~ al S ongoing in Israel has
parched farmland, forcing
Agricultural Research/November 2000
the country to import fresh water from Turkey for irrigation.
So Israeli horticulturist Amnon Erez, who recently retired from
the Volcani Center in Bet-Dagan, spent 4 months in Kear-
neysville last year learning about the film's stress-reducing
potential. Now back in Israel, Erez is overseeing a wide range
of crop studies to demonstrate Surround's ability to help plants
and trees thrive under extreme heat and water stress.
"He had never seen anything that affects a tree's micro-
climate as much as Surround does," says Peter Barrows, project
manager with Surround's producer, Engelhard Corporation of
Iselin, New Jersey.
Robin Matson, western field representative for Engelhard,
says Surround improves color and raises the sugar content of
Arizona-grown lemons, while preventing the trees from
shutting down under the hot temperatures common in the
Southwest. And Surround-coated grapes reach the desirable
sugar content-known as brix-a little sooner than those left
It All Began...
About 8 years ago, while looking for a way to reduce the
use of synthetic chemicals in orchards, Glenn conceived of
using kaolin particles as a physical barrier that would repel
insects and prevent disease organisms from digging in. He
approached Engelhard, one of the largest producers of kaolin,
about doing cooperative research.
Among its many uses, kaolin gives paper its whiteness and
is used in paint, pottery, and cosmetics. And it's safe to ingest.
A tiny bit of kaolin is already in aspirin and some other tablets.
(See "Particle Films: A New Kind of Plant Protectant,"
Agricultural Research, November 1998, pp. 16-19.)
But agricultural uses were uncharted waters. Early studies
by Glenn and ARS entomologist Gary J. Puterka showed that
the physical barrier controlled insect damage well. The type
of kaolin Glenn had selected for the studies transmitted visible
light and gases necessary for photosynthesis while reflecting
ultraviolet and infrared bands. But the film was difficult to
spray on the trees because it didn't suspend in water. So
Engelhard, under a cooperative research and development
agreement with ARS, removed the waterproofing additive,
improving kaolin's ability to mix with water. What's more,
leaving out the additive dramatically cut the cost of the product.
That started what may prove to be one of the most versatile
agricultural products ever to hit the market (see box on page
17). Surround Crop Protectant went commercial in 1999. This
year it was upgraded to a wettable powder formulation called
Surround WP Crop Protectant.
Barrows says Engelhard priced the product to compete with
insecticides. Since it is a physical barrier, it must be reapplied
to cover new growth or after a heavy rain, he says. The cost of
three to four applications of Surround is about equal to one
application of the insecticide pear growers use against pear
It was this tiny but devastating insect that boosted Surround
commercially last year. "We had intended to have a year of
trial usage," says Barrows. But entomologists found pockets
of insecticide resistance. "When it became known that
Surround controlled pear psylla as well as it does, we had to
make and ship a lot more than we anticipated."
Glenn stresses that "specially formulated kaolin has the
potential to greatly reduce pesticide use on conventionally
grown crops. The Organic Materials Review Institute has listed
Surround WP for organic food production."
Soil scientist Michael Glenn (left), entomologist Gary Puterka
(center), and Engelhard Corporation marketing director John
Mosko evaluate the particle film coverage and the color of
Insects Don't Like Biting the Dust
After several years of testing, the product is proving its
prowess against all shapes and sizes of insects. The white leaves
keep insects from recognizing their favorite hosts, and the tiny
particles ensure a lack of hospitality. Just as people don't like
climbing into a bed full of sand, insects don't like crawling on
a plant or tree covered with kaolin. It sticks to their wings,
legs, and mouth parts, so they quickly leave to find a more
comfortable place to feed and lay eggs.
In studies around the country, codling moths, apple maggots,
plum curculio, leafhoppers, Japanese beetles, rose chafer,
thrips, and rust mites-not to mention pear psylla-have fled
whitewashed crops in search of greener pastures. Even glassy-
winged sharpshooters-the transmitter of Pierce's disease,
which threatens to devastate southern California's grape
Agricultural Research/November 2000
vineyards avoid kaolin-treated lemon trees. And early results
suggest they'll stay away from treated grapevines too.
ARS' Puterka says the specially formulated kaolin parti-
cles "have the potential to work against almost any insect. The
key is getting good coverage of the crop. If you can get it to
stick and stay, it will control most insects." One crop that has
failed the stick test is cabbage, so Surround doesn't control
cabbage loopers and other worms. And because it's eventually
washed off all crops by rain, areas of low rainfall are most
adaptable to this technology, Puterka adds.
Don Gallagher of Gallagher Vineyards in Manteca,
California, was pleased with the early results of Surround on
12 of his 57 rows of grapes. "When I put it on, there were a lot
of mealybugs on the vines. But I can't find one of them now. I
don't know where they've gone." Gallagher did, however, find
a couple of mealybugs on insecticide-treated vines, he says,
noting that he's finding a similar pattern for leafhoppers on
Jay Brunner, professor of entomology at Washington State
University in Wenatchee, is looking at Surround's clout against
insect pests of the state's apple orchards. His results have been
mixed. "It's as good as many selective insecticides for con-
trolling Lacanobia fruit worms and leafrollers," he says. But
it proved only fair for codling moths and variable for stink-
bugs. Plus, it seems to interfere with helpful parasitic insects
that hang around the orchard and keep leafminers under con-
trol, Brunner adds.
In insect control, as in comedy, timing is everything. So
Brunner and other entomologists are working to determine the
optimum timing and application rates to control specific pests
without disrupting the biological control of others. "I think
Surround will have a place in certain pest-management
Technician Wilbur Hershberger uses infrared thermography to
evaluate the ability of water-repellent particle films to block ice
formation in frost-sensitive plants.
Under drought conditions, kaolin-coated trees often photosynthesize
faster than uncoated trees. In preparation to measure photosynthesis
rate of a whole tree, support scientist Patty Gundrum and Glenn
anchor a whole-canopy photosynthesis chamber.
programs where growers are trying to avoid pesticides," says
Todd DeKryger, agricultural research specialist with Gerber
Products Company in Fremont, Michigan, sees potential for
Surround to fit in with conventional methods to control specific
pests on specific crops. "It eliminates residues of conventional
pesticides and helps us maintain a stable supply of produce,"
This year, Gerber growers are trying it on pears, apples,
peaches, and carrots. DeKryger says it appears to work better
in the dry West because more of the film stays on the foliage.
"The jury's still out on its feasibility east of the Rockies," he
says, noting that May 2000 was the wettest May on record in
Fungi Dodge It, Too
While the potential for insect control got brighter, the
outlook for controlling orchard diseases didn't look very
promising ... until last summer. After some trial and error,
Glenn believes he has hit on the right formula by adding other
minerals to Surround. The minerals make the film more
alkaline (raise the pH), he says, and that seems to prevent
fungi from taking hold.
In the middle of July, Glenn's untreated apple leaves were
Agricultural Research/November 2000
contorted under the stress of powdery mildew infection. Not so
with the treated trees. Leaves lay flat and looked healthy. And
90 to 95 percent of the fruit were disease free. The mixture also
controlled apple scab.
"We still get the same insect control," says Glenn. "The min-
eral combination adds a new dimension."
And That's Only the Beginning
Uses for kaolin films don't end here. Glenn and Puterka also
see kaolin's potential as a carrier for just about any chemical
used on the farm-pesticide, fungicide, herbicide, pheromone-
you name it. "It can be used as a matrix to hold chemicals on
the plant or soil and get more even distribution," Puterka says.
Such improved delivery would benefit the environment, farm
workers, and consumers. "You may be able to reduce the active
ingredient by 50 percent or more," he says. The latest patent
application jointly filed by ARS and Engelhard covers this use
A water-repelling kaolin formula may have other appli-
cations. Tests show that this hydrophobic film protects tender
plants and trees from frost damage. Normally, when the tempera-
ture drops below freezing, ice crystals forming on a wet leaf
penetrate the surface and freeze the leaf tissue. Frost damage
can cost U.S. growers hundreds of millions of dollars annually.
But the waterproof kaolin keeps water from direct contact
with the leaf surface. And it makes water bead up, which further
reduces the surface area of the droplet resting on the leaf, says
ARS' Michael E. Wisniewski, a plant physiologist at
Kearneysville. In his tests in environmental chambers, kaolin-
treated tomato and bean plants have withstood temperatures as
low as 21F (-6C). They normally die when the thermometer
drops to 28F (-2C).
Wisniewski says Mick Fuller, professor of horticulture at
the University of Plymouth in England, is getting similar results
on citrus, potato, and grape plants in his environmental
chambers. "His findings are particularly impressive for citrus,"
In addition, other researchers are beginning to look at the
potential of kaolin-based products to address several other
needs-agricultural and otherwise. Kaolin's agricultural uses
"have opened a whole new area of science," says Puterka. So
far, they have spawned four patents jointly owned by ARS and
Engelhard Corporation, and five more patent applications are
either pending or being prepared.-By Judy McBride, ARS.
This research is part of Crop Protection and Quarantine,
an ARS National Program (#304) described on the World Wide
Web at http://ww.nps.ars.usda.gov.
D. Michael Glenn, Gary J. Puterka, and Michael E.
Wisniewski are at the USDA-ARS Appalachian Fruit Research
Station, 45 Wiltshire Rd., Kearneysville, WV25430-9423; phone
(304) 725-3451, ext. 321 [Glenn], ext. 361 [Puterka], ext. 320
[Wisniewski], fax (304) 728-2340, e-mail
mglenn @ afrs.ars. usda. gov
r The Versatile Horticultural Coating:
Proven and Potential Uses I
Field tests show that kaolin can:
control insect pests.
prevent sunburn on fruit and nuts.
prevent heat stress, thereby increasing
Some potential uses for kaolin in early stages
control fungal diseases.
prevent frost damage.
serve as a delivery system, allowing growers
to reduce the amount of chemicals applied.
Agricultural Research/November 2000
New Products To Suppress an
Old Insect Pest
SCOTT BAUER (K8408-1)
I n Wharton County, Texas, some
corn farmers say they must control
Mexican corn rootworms-the
predominant pest of corn in their
area-or get out of farming. To
alleviate their woes, farmers participating
in an areawide integrated pest manage-
ment (IPM) project to control corn
rootworms are getting a helping hand
from ARS agricultural engineer W. Clint
Hoffmann and others in the Areawide
Pest Management Research Unit at
College Station, Texas.
"Rootworms drive up the cost of farm-
ing in the Corn Belt and in Texas, which
ranks seventh in corn production. Almost
every acre of corn in Texas is treated with
soil insecticides at planting to limit root
damage caused by rootworm larvae.
These soil treatments are expensive-
ranging from $10 to $15 an acre-envi-
ronmentally unfriendly, and sometimes
ineffective at stopping rootworm infes-
tation," says Hoffmann.
Soil insecticides are among the most
toxic agricultural chemicals, and they
reduce adult rootworm emergence by
only 40 to 50 percent, according to ARS
entomologist Dale W. Spurgeon.
Several new adult-control products
have been developed that use lower doses
of toxicants. The Texas researchers
showed that with proper timing and
application methods, these products can
cut corn-rootworm damage while having
little or no harmful effect on the
Slamming the Corn Rootworm
In 1995, working closely with farm-
ers, extension personnel, and industry,
Hoffmann and ARS agricultural engineer
Ivan W. Kirk and other scientists at
College Station began an adult rootworm
control program using aerial applications
of Slam. Made by MicroFlo, Inc., in
Lakeland, Florida, Slam is based on
research by ARS entomologist Gerald
Sutter in Brookings, South Dakota.
A combination of a feeding stimulant
derived from wild buffalo gourd root and
the insecticide carbaryl, Slam reduced
the number of rootworm-infested acres
from 2,000 to 80 in the test area over 3
years with a carbaryl application rate of
just 1 ounce per acre. Carbaryl is
noimall\ applied at 2 to 3 pounds per
"Just as important, farmers in the
management area cut their use of soil
insecticides in half. Farmer, %\Ill still
use sonie soil insecticides to control
other soil insects. But this \\us our first
Chemical Insecticide Use
Research that improved microbial
insecticide formulations also led to
environmentally friendly chemical
Before some crops were genetically
transformed to resist certain insects,
scientists at the ARS National Center for
Agricultural Utilization Research and the
Biotechnology Research and Develop-
ment Corp., Peoria, Illinois, wanted to
solve a bugaboo of spray-applied biolog-
ical control agents: If rain didn't wash
away caterpillar-killing viruses and bac-
teria soon after they were sprayed on the
plants, the harsh sun would likely deal
these beneficial microbes a quick,
"The remedy on both counts turned
out to be a new spray formulation that
included the sticky protein wheat gluten,
made soluble by a chemical such as cit-
ric acid," said ARS entomologist Michael
R. McGuire. When spray droplets dry on
leaves, they stick like glue. The gluten
also shields the helpful microbes from the
sun's lethal ultraviolet rays. A patent was
issued in 1996.
In 1999, Bill Lingren, president of
Tr6ce, Inc., was seeking technology that
would help the company develop crop-
protection formulations that would in-
clude a feeding stimulant along with any
of several insecticides. By rotating use
of these agrichemicals, farmers could
help ensure that insecticide-resistant
strains of corn rootworms would not
quickly develop in their fields.
In a cooperative research and devel-
opment agreement (CRADA) between
ARS and Tr&c6, the sticky wheat-gluten-
based formulations again proved useful.
The company licensed the invention and
now markets it under the name CideTrak.
When combined with any of at least three
Agricultural Research/November 2000
SCOTT BAUER (K8407-19)
victory with a product
using a low dose of
toxicant to control
adult beetles," says
Because thdie west-
ern corn rootm% orm has
de\ ehoped resistance
to caih.nir 1. making it
Miparticularol difficult to
-- control in Nebraska,
mt C o other companies
tc pes of insecti-
carbamates, and or-
one-tenth the normal
rates of application,
CideTrak has worked
better than conven-
tional sprays, says
Scott Lingren, Tr6c6's
global field develop-
ment manager. The
partners have ex-
tended the CRADA
into 2001 as they test
when combined with
By Ben Hardin,
The research is
part of New Uses,
Quality, and Market-
ability of Plant and
Animal Products, an
ARS National Program (#306) de-
scribed on the World Wide Web at http:
//www. nps.ars. usda.gov.
Michael R. McGuire, formerly at the
USDA-ARS National Center for Agri-
cultural Utilization Research, Peoria,
IL, is now in the USDA-ARS Western
Integrated Cropping Systems Research
Unit, 17053 Shafter Ave., Shafter CA
93263; phone (805) 746-8001, fax
(805) 746-1619, e-mail mrmcguire@
Agricultural Research/November 2000
ARS pilot Hal Tom flies an Air Tractor
402B aircraft spraying an insecticide
mixture on a test field. Blue dye aids in
locating and measuring the product.
have launched new products that allow
farmers to use one-tenth the labeled rate
of any other toxicant labeled for corn-
-CideTrak (see sidebar) and Invite.
ARS entomologist Robert F.W.
Schroder, of the Insect Biocontrol
Laboratory in Beltsville, Maryland,
concocted Invite by using Hawksberry
watermelon juice as the feeding
stimulant. The active ingredient in
Invite is water soluble, according to
Schroder. Invite is made by FFP
AgroTech, Inc., in Eustis, Florida.
Recent performance trials in Grang-
er, Texas, of CideTrak and Invite-each
combined with several different types
of toxicants-showed effective root-
worm control, according to Hoffmann.
Baits and Traps
Knowing when to apply insecticides
is essential to any insect-control
program. To take the guesswork out of
timing spray applications, Tr6c6 de-
signed a trap with a kairomone a scent
that mimics the adult beetle's favorite
food. The plastic dome-shaped trap
looks somewhat like an ice cream
sundae container. The traps are placed
30 feet inside the cornfield.
Twenty years ago, managing corn
rootworms was simple: just rotate crops
from corn to soybeans. "Now, we're
finding new corn rootworm strains
laying their eggs in blooming soybeans
and sorghum. Traps help us determine
when adult treatments are needed so we
can prevent that from happening," says
Another Threat: Aflatoxin
Besides corn rootworms, yet another
daunting foe of corn growers in this man-
agement area is aflatoxin, which affects
food safety and corn prices.
Could there be a connection between
the number of beetles and the incidence
of aflatoxin? ARS palynologist (one who
studies pollen) Gretchen D. Jones thinks
"In 1998, the scientists found 50 per-
cent less aflatoxin in the area with low
numbers of adult rootworms than in the
untreated areas," she says.
To confirm this phenomenon, Jones
covers individual corn plants with insect-
proof bags, ensuring that no insects or
pollen can enter. Soon afterward she pol-
linates the plants using aflatoxin-free
Once it's known whether or not the
Mexican corn rootworm spreads aflatox-
in to corn, farmers will have one more
reason to control the insects over a large
The Areawide Corn Rootworm Man-
agement program is one of several
national areawide IPM programs driven
by USDA's commitment to reduce
reliance on agricultural chemicals. The
nationwide programs, which also include
control of codling moths, leafy spurge,
and stored-grain insects, began in
1994.-By Linda McGraw, ARS.
This research is part of Crop Produc-
tion, an ARS National Program (#305)
described on the World Wide Web at
To reach the scientists mentioned in
this article, contact Linda McGraw,
USDA-ARS National CenterforAgricul-
tural Utilization Research, Information
Staff, 1815 N. University Street, Peoria,
IL 61604; phone (309) 681-6530, fax
(309) 681-6690, e-mail mcgraw@ars.
Learning To Live With Japanese Brome
There's little chance that land managers will rid grasslands
in the Northern Plains of the weedy annual grass called Japanese
brome, also known as Bromusjaponicus. So ARS researchers
in Miles City, Montana, are helping ranchers live with it.
The scientists are correlating rainfall and other environmental
factors with the amount of the weed available for grazing, to
help ranchers make the best use of both the weed and the native
Japanese brome can make up as much as 40 percent of the
forage available on the mixed-grass prairies of Montana,
Wyoming, and the Dakotas.
"When the plants are young, they make nutritious, palat-
able forage for cattle," says ARS range scientist Marshall R.
Haferkamp. "They also don't develop seedheads as prickly as
cheatgrass, a relative of Japanese brome that's pervasive in other
The problem is that the amount of forage annual grasses
produce varies greatly, ranging from as low as 20 pounds per
acre to more than 600 in the spring. Annual bromes contribute
over 60 percent of this production. That makes using brome as
food for a cattle herd unpredictable.
"Ideally, livestock would graze brome-infested pastures
during early spring and then move to other pastures," says
Haferkamp. "But we don't always know how much brome for-
age will be produced each spring. Grazing these pastures when
brome forage is scarce may hinder development of the associ-
ated perennial grasses."
The goal is to help ranchers better balance the use of various
rangeland resources. To do that, the scientists need to understand
what controls the growth rate of Japanese brome. They're
measuring soil moisture, soil nitrogen, and precipitation to find
out how well each factor predicts brome productivity. They're
also looking at how the weed affects production of preferred
perennial grasses. They plan to produce a decision-support
system to help farmers plan grazing strategies based on each
year's variable environmental conditions.-By Kathryn Barry
Marshall R. Haferkamp is with the USDA-ARS Fort Keogh
Livestock and Range Research Laboratory, Route 1, Box 2021,
Miles City, MT 59301-9202; phone (406) 232-8211, fax (406)
232-8209, e-mail email@example.com. *
Lactic Acid Reduces Microbes in Poultry
Lactic acid, commonly used in foods as a flavoring or
preservative, reduces Salmonella in two major organs in broiler
chickens, according to ARS studies in College Station, Texas.
One organ, called the crop, is part of the chicken's
esophagus, which leads from the mouth to the stomach. The
other organ, the ceca, is a pouch connected to the large intestine.
"Both the crop and ceca are especially prone to bacterial
contamination," says microbiologist J. Allen Byrd, of the ARS
Food and Feed Safety Research Unit.
Eight to 10 hours before slaughter, broiler chickens are
usually taken off feed to reduce intestinal contents. During
this time, they look for food and peck at whatever is on the
ground. What the birds eat enters the crop and is slowly released
into the stomach. If Salmonella is present, the highest
concentration is found in the ceca. But the amount of bacteria
in the crop is also significant because it ruptures 86 times more
often than the ceca during processing.
By adding 2 tablespoons of lactic acid to 1.2 gallons of the
chickens'drinking water, scientists reduced Salmonella by 41.5
percent in the crop and by 11.2 percent in the ceca, compared
to birds drinking plain water.
Why would this simple tactic thwart one of the worst
foodborne pathogens in poultry? Lactic acid acidifies crop
contents, making them less conducive to bacterial growth. This
method is an inexpensive way to help keep foodborne
pathogens at bay-the cost is about 0.2 cents per bird using
food-grade lactic acid. Researchers are studying other tactics
to identify potential hot spots in the processing chain that may
lead to bacterial contamination.
Salmonella can cause diarrhea, vomiting, and sometimes
death. The bacteria, which can be killed by thoroughly cook-
ing food, sicken an estimated 3.8 million Americans each
year.-By Linda McGraw, ARS.
J. Allen Byrd is in the USDA-ARS Food and Feed Safety
Research Unit, 2881 F&B Road, College Station, TX 77845;
phone (979) 260-9331, fax (979) 260-9332, e-mail
Agricultural Research/November 2000
The Cause of Bronze Wilt of Cotton
A mysterious cotton disease
known as bronze wilt appeared
in the Midsouth and Southeast
during the hot summers of 1995,
1996, and 1998. Similar disease
symptoms were seen in peanuts and soy-
Bronze wilt flourishes when daytime
temperatures are above 95F for 2 to 3
weeks. In 1996, this occurred in late June
and early July.
"We first saw the dramatic evidence
of this disease around the 4th of July,
causing me to think of it as the 'Fourth
of July disease,'" says ARS plant pathol-
ogist Alois A. Bell in College Station,
Texas. "That isn't necessarily the case
every year, but there is a significant re-
lationship between high, sustained tem-
peratures and outbreak of the disease."
In 1996, several commercial seed
companies asked Bell to determine the
cause of bronze wilt. The disease, which
causes death of feeder roots and deficien-
cies of phosphorus and potassium in
tissues, took its toll on cotton grown in
Arkansas, Georgia, Louisiana, Mississip-
pi, South Carolina, and Texas.
In 1998, cotton losses in Georgia were
valued at nearly $25 million. Even Pima
varieties of cotton grown in Arizona and
California showed yield losses that year.
Last summer, Texas and South Caro-
lina had relatively cool temperatures
during June and early July, but tempera-
tures exceeded 95 'F during late July and
most of August. High temperatures dur-
ing this stage of cotton development
caused excessive abortion of bolls and
Bell found two species of bacteria in
seed from 24 farms in the upper coastal
area of Texas. Greenhouse studies con-
firmed that heat stress and the bacterial
species contributed to reduced yields of
between 20 and 50 percent and led to
poor fiber and seed quality.
Wilted leaves of affected plants turn
reddish to copper just before the plants
Agricultural Research/November 2000
collapse. Diseased plant stems turn deep
red to maroon. "During the day, I've
placed my hands on the leaves of affect-
ed plants and found them warmer than
comparable leaves of healthy plants. The
higher leaf temperature is probably
caused by the limited ability of damaged
feeder roots to take up water from the
soil," says Bell.
Bell discovered that a new strain of
the bacterium Agrobacterium tumefa-
ciens is associated with bronze wilt and
is present in the seed of all U.S. cotton
varieties. He was the first scientist to iso-
late the newly discovered strain, called
biovar 1, from both seeds and roots of
affected cotton, peanuts, soybeans, and
Though this doesn't prove that the
bacterium causes bronze wilt, there is a
high correlation between the presence of
the bacterium and disease symptoms.
More research is needed to pin down the
precise relationships between the organ-
ism and bronze wilt.
Searching the "B Genes"
Bell believes he's on the track of re-
vealing important genetic reasons why
some plants are more susceptible than
others to bronze wilt. In several areas of
the Cotton Belt, popular cotton varieties
are bred with specific genes that convey
bacterial blight resistance and early fruit-
ing, explains Bell.
The resistance genes used in tra-
ditional breeding programs are generally
referred to as "B genes." Three genes--
B2, B3, and B7-are in the genetic
background of Tamcot SP37, a Texas
cotton variety that has been used in many
breeding programs worldwide. This
variety provides the desired early fruit-
ing, which permits farmers to save on
"Breeders who used Tamcot SP37 as
a parent for earliness could have inad-
vertently separated the B genes from
each other. Greenhouse studies showed
that varieties with B7 alone are very sus-
ceptible to bronze wilt and develop high
Agrobacterium populations in roots.
"Cystic fibrosis in humans is a good
parallel for explaining what may be
happening genetically in cotton," says
Bell. "Plants with one dominant and one
recessive gene remain healthy, but when
they have two recessive genes they
develop bronze wilt. It's the same in
people carrying one recessive gene and
one dominant gene for cystic fibrosis-
they are only carriers for the disease.
But if two carriers have children, one-
fourth of their offspring will likely have
two recessive genes and be stricken
with the disease," explains Bell.
A genetic test-like the ones avail-
able for sickle cell anemia or cystic
fibrosis-will need to be developed to
further confirm these speculations. Bell
is looking for genetic markers to use in
tests for identifying seed stocks that
may carry the genes for susceptibility
to bronze wilt.
For now, there is no cure for bronze
wilt. Avoiding use of highly suscepti-
ble varieties and minimizing heat stress
may be the best means of prevention.
One study suggests that farmers should
avoid using nitrogen fertilizer alone
without other nutrients.
Other researchers in the Southern
Plains Agricultural Research Center in
College Station, Texas, are collaborat-
ing with Bell to look for fungal and
bacterial biocontrols. Such biocontrols
may, at best, reduce the severity of
disease, as will attempts to correct
phosphorus deficiencies in the plant.-
By Linda McGraw, ARS.
This research is part of Plant Dis-
eases, an ARS National Program (#303)
described on the World Wide Web at
Alois A. Bell is in the USDA-ARS
Cotton Pathology Research Unit,
Southern Plains Agricultural Research
Center 2765 F&B Rd., College Station,
TX 77845; phone (409) 260- 9518, fax
(409) 260-9470, e-mail abell@acs.
Udderly stubborn staph suc-
cumbs to test vaccine. But
will it prevent infection?
ARS dairy scientist Albert Guidry credits cooperation among ARS, state universities,
dairy producers, and industry for the success of the Staphylococcus aureus vaccine
Al Guidry is looking for a herd of
He could use about 1,000 of
these adolescent cows to test a
new vaccine against the tough-
est form of mastitis-the kind caused by
Staphylococcus aureus. Current com-
mercial vaccines immunize against two
staph strains that cause only about 40 per-
cent of staph-induced mastitis cases in
the United States, slightly more in Eu-
rope. And antibiotics are ineffective
against staph because the bacteria have
become resistant, or they have holed up
in regions of the gland where the drugs
So Guidry, a dairy scientist at the
Beltsville (Maryland) Agricultural Re-
search Center, went looking for the miss-
ing links. He screened 44 percent of the
U.S. dairy herd to find the serotypes re-
sponsible for the other 60 percent of
staph-related mastitis cases.
Collaborator Ali I. Fattom, with the
biotechnology company Nabi in Rock-
ville, Maryland, had what Guidry was
looking for: a single serotype of S. au-
reus-called 336. Fattom, who is in-
volved in developing a human vaccine
against staph, knew that 336 accounts for
only about 10 to 12 percent of human
staph infections. In U.S. cows, however,
it's responsible for 50 to 60 percent.
The result of this collaboration is a
trivalent vaccine containing 336 togeth-
er with the other two staph strains known
to cause mastitis. Whether or not the new
vaccine will prevent mastitis still needs
to be proved. But it can cure it-even a
good percentage of the most recalcitrant
cases-when combined with antibiotics.
That's according to tests being led by
another of Guidry's longtime colleagues,
Michigan State University veterinary
scientist Phil M. Sears.
Sears had been looking for a way to
boost the bovine immune system, hop-
ing that a more vigorous immune re-
sponse combined with antibiotics would
control chronic mastitis. And he had
good results. When he isolated the caus-
ative S. aureus strain from a dairy herd,
killed it, then injected it back into the
infected cows a few weeks before admin-
istering antibiotics, he cured more than
But isolating the causative agent from
each herd is too cumbersome for com-
mercial use. The trivalent vaccine ap-
pears to solve this problem.
"It applies to all herds, and it's a pur-
er, cleaner preparation," says Guidry.
When Sears tested it in commercial dairy
cows, it proved to be as effective as his
herd-specific vaccine, curing 55 to 60
percent of infected cows.
Because of these promising results,
Sears is confident the vaccine will protect
heifers from infection. "I don't have any
doubt," he says, noting that the vaccine
cleared staph infections in about 10
percent of infected cows-even before
he administered antibiotics. And it
cleared 7 of the 9 cases in the Beltsville
herd with the administration of anti-
biotics, Guidry adds.
Nabi and ARS are jointly applying for
a patent covering the new vaccine. The
company will look for a partner with
channels in the agricultural arena to fund
further studies and market it. Before the
vaccine can go to market, its ability to
prevent infection needs additional vali-
dation, says Guidry.
He figures that will require several
years and a whole lot of heifers.-By
Judy McBride, ARS.
This research is part of Animal
Health, an ARS National Program
(#103) described on the World Wide Web
at http://ww. nps.ars.usda.gov.
Albert J. Guidry is with the USDA-
ARS Immunology and Disease Resis-
tance Laboratory, 10300 Baltimore Ave.,
Bldg. 173, Room 105, Beltsville, MD
20705-2350; phone (301) 504-8285, fax
(301) 504-9498, e-mail aguidry@lpsi.
Agricultural Research/November 2000
Spraying Fruit Trees
to a "T"
Field tests show the effectiveness of
a new T-shaped sprayer developed by
Michigan State University engineers to
apply pesticides in orchards. The spray-
er uses about 50 percent less chemical
per acre and cuts application time in half.
This is because it travels above the trees,
moving up and down 5 to 17 feet above
ground to accommodate tree height. It
can spray two rows at once, sending low-
volume, uniform droplets directly down
into the trees.
The sprayer uses only about 25 gal-
lons to cover an acre. Current air-blast
equipment sprays about 50 gallons an
acre, one row at a time, shooting straight
into the air and giving uneven coverage.
Growers are evaluating the new sprayer
for use on grapes, blueberries, and stone
fruits. Charles C. Reilly, USDA-ARS
Southeastern Fruit and Tree Nut Re-
search Laboratory, Byron, Georgia;
phone (912) 956-6409, e-mail creilly@
Tackling Trouble on the
ARS and Brazilian scientists have
teamed up for a new investigation of the
microbe that causes Pierce's disease in
grapevines. The collaboration will reveal
the makeup, or sequence, of all of the
genes in the bacterium, Xylella fastid-
iosa, the organism responsible for this
costly disease. In northern California,
Pierce's disease has chronically attacked
vineyards. More recently it has plagued
southern California vineyards, as well.
A half-inch-long insect known as the
glassy-winged sharpshooter can harbor
Xylella in its gut, then move the pathogen
into plants when it punctures grapevine
stems to feed. Severely infected vines
Brazilian scientists have already
sequenced the genome of a related
Xylella fastidiosa strain that causes a
Agricultural Research/November 2000
disease known as citrus variegated
chlorosis. In addition to ARS, sponsors
of the new research venture are the
American Vineyard Foundation, the
California Department of Food and
Agriculture, and Brazil's State of Sdo
Paulo Research Foundation. Kevin J.
Hackett, USDA-ARS National Program
Staff, Beltsville, Maryland; phone (301)
504-4680, e-mail firstname.lastname@example.org.
JACK KELLY CLARK, COURTESY OF UC REGENTS
Glassy-winged sharpshooter. Shown about 3
times actual size.
CO2 Could Aggravate
Another result of rising atmospheric
CO2 may be an increase in ragweed pol-
len. Researchers have made pollen
counts on ragweed grown in indoor
chambers at various levels of atmospher-
ic CO2. The gas levels ranged from the
turn-of-the-century level of around 280
parts per million (ppm) to today's 370
ppm and the 600 ppm predicted by the
year 2100. Pollen production went from
5.5 grams to 10 grams to 20 grams per
plant as CO2 moved through these three
Experiments have since moved
outside, with researchers checking on
ragweed pollen production in urban,
suburban, and rural areas around Bal-
timore, Maryland. The project is a
collaborative effort of Johns Hopkins
University School of Public Health,
Towson University, and Multidata
Corporation. Lewis H. Ziska, USDA-ARS
Climate Stress Laboratory, Beltsville,
Maryland; phone (301) 504-6639,
Tolerance in Small Grains
The third most abundant element in
the Earth's crust, aluminum is a major
component of soil clay. It causes no
problem in neutral or alkaline pH, but
in acidic soils, it damages plant root sys-
tems and greatly reduces crop yields.
More than half of the world's 8 bil-
lion acres of potential agricultural
land-including about 86 million U.S.
acres-have an aluminum problem.
Researchers want to develop crop
varieties with increased genetic resis-
tance to aluminum. They've identified
genetic markers for a single gene in bar-
ley that enhances aluminum tolerance.
These markers may be used in plant
breeding programs aimed at shuttling
aluminum-tolerance genes from tolerant
barley varieties to aluminum-sensitive
Study results also suggest that alumi-
num tolerance in barley and in wheat,
its close relative, may be owing to the
action of different forms of the same
gene. So it may be possible to engineer
increased aluminum tolerance in barley
by introducing a wheat gene for alumi-
num tolerance. DavidR. Garvin, USDA-
ARS U.S. Plant, Soil, and Nutrition Lab-
oratory, Ithaca, New York; phone (607)
255-7308, e-mail email@example.com.
Correction: The cover photo of
the September 2000 issue shows
orchids and anthuriums.
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