Page B—Corn Talk, Lancaater Farming, Saturday, January 29, 2000
In 2001, Bt Corn Technology Will Provide Rootworm Control At Root Zone
ANDY ANDREWS
Lancaster Farming Staff
LANDISVILLE (Lancaster
Co.) Beginning in 2001,
about 1 percent of the com
acreage in the U.S. will be com
prised of Bt com that fights
com rootworm where it matters
most at the roots.
The Bt variety, marketed
under unspecified variety
names by a major seed produc
er, will be another transgenic
com tool to fight destructive
crop pests. But producers need
to keep in mind that transgenic
com coming out may not pro
tect against black cutworm and
other pests, according to Den
nis Calvin, Penn State
entomologist.
Calvin spoke to about two
dozen crop management exper
ts and industry representatives
in mid-December at the first of
a Penn State-sponsored two
day Capitol Region Crop Insect
and Disease Management
School at the Penn State Exten
sion Southeast Regional Labor
atory near Landisville.
If com producers are to use
the new Bt varieties, it’s possi
ble they’ll need other insect
type controls using standard
chemical treatments or in com
bination with an overall indus
try approved integrated pest
management (IPM) program.
Today’s varieties of Bt com
do not control black cutworm
and provide little control of
stalk borer, fall armyworm, or
com earworm.
The new com rootworm Bt
“stacked” varieties, noted Cal
vin, would be expressed at the
larvae stage of the com
rootworm.
Penn Stale tested a variety of
com rootworm Bt this past
year. Unfortunately the drought
wiped out the rootworm popu
lation, though “what we did
have looked good,” said Cal
vin. The control was the same
as other standard soil insecti
cide programs, though using
the Bt type controls could push
costs slightly higher. It’s not
clear yet what the premium
costs could be. More woric is
necessary, he noted, at the Penn
State Rockspring research farm
and at a private farm where test
ing is under way.
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Calvin and other crop man
agement experts provided an
introduction to the philosophy
of pest management through
IPM at the school.
The use of Bt com as part of a
program has raised some con
cerns over the Monarch butterf
ly controversy. Lab studies
indicated that it is possible the
pollen from Bt com can kill
Monarch butterflies, and indus
try and academia has been
under heavy criticism from the
public.
Calvin said he spent time at
two conferences this fall,
including two days in Chicago,
reviewing the Bt and Monarch
butterfly controversy. Appa
rently, the Bt 176 type can have
a 10-fold expression in the com
pollen, yet only 1-2 percent of
the Bt com planted uses this
type. The Bt 176 type only
expresses up to eight yards
from the edge of a field. More
field studies of the effects of the
Bt com on the butterflies may
be needed.
Favorite pollen-feeding
plant species for the Monarchs
are milkweed and dogbane. In
lowa and Illinois, milkweed
grows on the roadways. A milk
weed variety in Kansas, Blue
Vine, is a really good host for
the butteries.
Much of the information
about the potential toxicity of
Bt to the butterflies has been
“taken out of context to stir
something up,” Calvin noted.
But the controversy has allow
ed the industry to step back and
reexamine other, more “holis
tic” ways, friendly to the envi
ronment. to control pests.
Calvin referred to the prog
rams outlined in the Penn State
issued Field Crop IPM Guide,
available for $75 from the
Capitol Region Extension
Agronomy Team. More detail
about the program is available
by contacting Del Voight at the
Lebanon extension office at
(717) 270-4391.
For now, growers have
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Several crop insect and disease management experts spoke to shout two
dozen crop msnagement experts and industry representatives in mid-
December at the first of s Penn State-sponsored two-day Capitol Region Crop
Insect and Disease Management School at the Penn State Extension South
east Regional Laboratory near Landisville. From left, looking over a predator
beetle model, John Ayers, Del Voight, and Dennis Calvin.
embraced the Bt com, which
uses a natural biological control
embedded in com genes, to
control the European com bor
er. The industry has “made a lot
of strides in the genetic method
of pest management,” said Cal
vin. But with those advances
have come new strategies to
ensure its long-term effective
ness and viability.
IPM emphasizes taking a
look at the crop grown, the rota
tion, the cultural practices, the
soil and environment types,
consistent scouting, and under
standing effective timing and
application of pesticides. Pro
ducers must look at the eco
nomics of the use of different
technologies to see if they’ll be
useful.
Finding that "economic
threshold,” Calvin noted, is
key. The issue is, “when do I
treat to get the most effective
control?” Fact is, the economic
thresholds are “not based on as
much science as we think,” Cal
vin noted.
GSI
For example, for the com
leaf aphid, the threshold is 25
aphids per foot of row in the
fall, or 100 aphids per foot of
row in the spring.
To fmd those thresholds, a
computer spreadsheet program
was shown at the school.
In the past, to control the
com borer, no economic treat
ments were available in the reg
ion. Only a small percentage of
growers could justify using
standard treatments. But with
Bt com, the borer became an
economic concern, now that
technology has arisen to treat it.
according to Calvin.
“This changed the econom
ics of managing the pest,
because we have a tool that
does a much better job,” noted
the Penn State entomologist. Bt
com offers almost complete
control of the pest under good
growing conditions.
Calvin noted several resour
ces for producers. If there is one
book that offers a complete
index of information from tden-
tification to insect biology, he
recommended the reference,
“Handbook of Com Insects,”
available from the Entomologi
cal Society of America (Land
ham. Md., 1999, 174 pp., $35.
ISBN 0-938522-76-0,
301-731-4535). For com refer
ence, if there was one book to
identify insect pests, “this
would be it,” he said.
For soybeans, Calvin recom
mended die “Handbook of Soy
bean Pest Insects,” available
from the society (1994,142 pp.,
$25, ISBN 0-938522-29-9). r
Penn State has its own IPM’
Website at
www.fra.cas.psu.edu/
Calvin also recommends the
“ Penn State Agronomy Guide,”
also available on the Web at
http://agguide.agronomy.psu.c
du/
Del Voight, crop team mem
ber and Lebanon extension
agent, and John Ayers, Penn
State plant pathologist,
reviewed ways to diagnose dis
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