January 2021 - 23

SWEET CORN
to eliminate pre-silk treatments and
reduce insecticide applications during
silking by more than 80%. However,
ear damage, kernel consumption, and
numbers of surviving older larvae have
progressively increased since 2004 in
Attribute sweet corn.
Based on 30 trials evaluated in 2019,
ears damaged by CEW averaged 66.4%
in Attribute BC0805 compared to
73.2% in the non-Bt isoline Providence,
and 11 of these trials recorded the
same or higher ear damage and larval
infestations in the Bt plots. Cry1Ab
expression still shows some inhibition
of kernel consumption and larval
development, suggesting that CEW has
not completely lost susceptibility to this
toxin. This reduction in control efficacy
over time is unrelated to corn earworm
pressure, because moth activity has
actually declined over the past decade at
most trial sites. Currently, many sweet
corn producers have stopped growing
Attribute sweet corn or are applying
insecticide sprays to compensate for the
reduced efficacy.
Performance Series varieties include
Temptation II, Obsession II, SV9012SD,
SV9014SB, and SV9010SA. Besides
expressing the dual insecticidal toxins to
control lepidopteran larvae, these varieties
also express Cry3Bb1 to control rootworms
and the Roundup Ready technology. When
Performance Series sweet corn was first
Performance, management keys
Current field performance and management of Bt
sweet corn are summarized as follows.
First, all Bt sweet varieties provide 100% control of
ECB, and there is no evidence of any change in corn
borer susceptibility to the Cry or Vip toxins in the midAtlantic
region. Second, the herbicide tolerance traits in
these varieties offer a weed control advantage over their
non-Bt counterparts. Attribute sweet corn still provides
good control of FAW during the vegetative growth stages
but only moderate ear protection; no effective control
of western bean cutworm; and generally poor to fair
control of CEW.
Performance Series sweet corn provides very
good control of FAW during the vegetative and ear
development stages but no effective control of western
bean cutworm and only poor to fair control of CEW.
Although CEW has developed moderate to high levels
of resistance to the expressed toxins, the green silk
tissue in the Attribute and Performance Series sweet
corn is still consistently toxic to newly hatched larvae,
evaluated in 2010, insect control efficacy
was even higher than the level of ear
protection by Attribute hybrids, providing
100% control of fall armyworms and more
than 98% control of corn earworms.
However, control efficacy against CEW
has rapidly declined during the last five
years as evident in unacceptable levels
of kernel damage on the ear tip of both
RAISING THE BAR
XANADU
causing intoxication and delayed growth; so those
larvae that survive are exposed longer before entering
the ear. Due to this wider window of exposure, the first
insecticide application in both Bt types can be applied
at 100% fresh silking, usually three or four days later
than the first application in non-Bt sweet corn under
the same insect pressure.
Additionally, pyrethroids and other insecticides may
actually work better because larvae are weakened by
the Bt intoxication. A second spray 3 to 4 days later is
usually necessary if high moth activity continues, and
sometimes three or four applications may be needed
depending on the ear quality required. Attribute II sweet
corn still provides excellent control of all foliage-feeding
and ear-invading worms, thus no insecticidal sprays
are required in most cases, except for secondary pests
such as sap beetles. Further, the lack of kernel injury in
Attribute II sweet corn significantly reduces the risk of
sap beetle infestations, since these insects are mainly
attracted to previously damaged ears.
Attribute and Performance Series sweet
corn. The dual toxin expression still
results in more inhibition of CEW kernel
feeding and larval development compared
to the Cry1Ab sweet corn; and also note
that the Attribute ears can show extensive
feeding injury by FAW on the side
kernels, whereas the Obsession II ears are
undamaged by this pest.
Varieties Pursuit, Aspire, Remedy,
Milky, Patriarch and Protector also
express tolerance to glufosinate and
glyphosate herbicides. Compared to
Attribute and Performance Series sweet
corn, these Bt varieties provide excellent
field efficacy against CEW and FAW,
including black cutworm and western
bean cutworm. VGN
Xanadu
Maturity: 74-75 day
Ear Size: 8 x 1.75-2 "
Nirvana
The
Series
C
o
™
Xanadu is part of The Nirvana Series™
and provides
your customers with unique taste and texture. Growers
appreciate its higher ear placement, improved disease
resistance, consumer appeal, and post-harvest shelf life.
RAISING THE BAR
IN QUALITY, FLAVOR, AND YIELD
Bringing you the best products in partnership with Crookham.
Elevate your sweet corn experience with The Nirvana Series™
.
Visit ruppseeds.com to request or download your copy
of our 2021 catalog including 40 new products.
800-700-1199 * ruppseeds.com
VGN | JANUARY 2021 | 23
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January 2021

Table of Contents for the Digital Edition of January 2021
