The Georgia Agricultural Experiment Stations
College of Agricultural and Environmental Sciences
The University of Georgia
Research Report Number 696
October 2004
Insect Screening Results
Evaluation of Corn Hybrids for Resistance to Insects
Xinzhi Ni and Matthew D. Krakowsky
During the growing season of 2004, the environmental conditions in southern Georgia
were favorable for the rapid buildup of insect populations, providing the potential for
considerable damage to the corn crop. The four most common ear-feeding insects
collected in our trials were the corn earworm, the fall armyworm, the maize weevil, and the
pink scavenger caterpillar. These ear-feeding insects usually cause the greatest amount
of damage in the late-planted corn, or in the corn left in the field for an extended period
past maturity.
Percent yield losses attributable to all insects for individual hybrids varied from 0.4% to
7.6% and are reflected by VG, G, F, P, and VP ratings in the tables. Hybrids in the two
tests sustained average yield losses of 4.1% and 2.4% in the short-season and mid-season
hybrid tests, respectively. The mean yield loss for all tests was 3.1%. Of the total loss,
about 9% was attributable to feeding damage by the corn earworm and the fall armyworm,
41% to the maize weevil, and 50% to the pink scavenger caterpillar. Losses to the pink
scavenger caterpillar and maize weevil were based on damage by multiple generations of
these insects as the corn dries in the field. Timely harvest can substantially reduce losses
caused by these two insects.
Hybrids resistant to insects are highly recommended for planting and are presently the
most economical means, especially in late plantings, for the reduction of ear-feeding insect
damage. Consult your local county agent and/or extension entomologists for additional
control recommendations for other insects.
Evaluations for resistance to corn earworm and fall armyworm, maize weevil, and pink
scavenger caterpillar are given for hybrids in the following tables. Lettered ratings in the
tables refer only to relative resistance to insects and are not indicative of yield. Thus, a
hybrid rated poor for resistance to insects might be among the best for yield and viceversa. Please refer to the yield data in other tables for specific information.
During the damage evaluation process, husk tightness ratings were assigned using a scale
of 1 to 5, in which 1 = very loose and 5 = very tight. Because average rating for husk
tightness is between 3.0 and 4.9, only loose (L), medium (M), and tight (T) ratings are given
in the tables.
Both short-season and mid-season tests were planted on April 19, 2004. Plots were
thinned to 20,000 plants per acre. Ratings for overall ear-feeding insect damage were
completed during October 2-4, 2004. Data for this section was compiled by J. C. Mullis
and J. M. Cook of the United States Department of Agriculture, Crop Genetics and
Breeding Research Unit, Coastal Plain Experiment Station, Tifton, Georgia.
Research Report Number 696
October 2004
The Georgia Agricultural Experiment Stations
College of Agricultural and Environmental Sciences
The University of Georgia
Tifton, Georgia:
Short-Season Corn Hybrids, 2004
Evaluations for Resistance to Insects and Other Traits
Overall Resistance
to Insect Injury 2
2 or more
years
2004
Hybrid
Name
Days to
Antheses
Husk
Tightness1
Croplan Genetics
Hytest
DeKalb
Terral
AgraTech
799Bt
7799Bt
DKC63-52(RR2/YGCB)
TVX26BR401
755RRBt
57
57
57
58
59
M
L
M
T
T
VG
VG
G
G
G
-
Terral
NK
Hytest
Pioneer
Croplan Genetics
TV26BR10n
1851W*
7806Bt/RR
34B24(YGCB)
691LL/Bt
57
61
58
57
57
M
M
T
M
M
G
G
G
F
F
F
G
F
F
Pioneer
Hytest
Terral
Hytest
Terral
33M54
7729Hx/LL
TVX26B401
7761RR
TV2160Bt
58
58
59
56
59
M
T
L
M
M
F
F
F
F
F
F
-
AgraTech
Croplan Genetics
Pioneer
Terral
Terral
733RR
705RR
32R25
TV2140
TV2140nRR
59
56
61
61
60
M
M
T
L
L
F
F
P
P
P
F
F
F
Terral
Terral
SS
Pioneer
Vigoro
TVX23R401
TVX23R31
E83462
33V15
V56Y51
62
60
57
58
58
L
M
M
T
M
P
P
P
P
VP
F
-
TV2130
8112
60
59
M
M
VP
VP
P
-
Company or
Brand Name
Terral
Golden Acres
* White hybrid. OR Full-season hybrid.
1. L = loose husks, M = medium-tight husks, and T = tight husks.
2. Overall insect resistance to ear-feeding insects (i.e., the corn earworm, the fall armyworm, the maize
weevil, and the pink scavenger caterpillar). The damage measured by the percentage of kernels
infested with the ear-feeding insects from five ears, where VG = very good, G = good, F = fair, P = poor,
and VP = very poor.
The Georgia Agricultural Experiment Stations
College of Agricultural and Environmental Sciences
The University of Georgia
Research Report Number 696
October 2004
Tifton, Georgia:
Mid-Season Corn Hybrids, 2004
Evaluations for Resistance to Insects and Other Traits
Overall Resistance
to Insect Injury 2
2 or more
years
2004
Company or
Brand Name
Hybrid
Name
Days to
Antheses
Husk
Tightness1
Croplan Genetics
AgraTech
Garst
Greenwood
Greenwood
895Bt
999Bt
8230IT
865*
863*
58
59
57
62
62
T
M
M
M
L
VG
VG
VG
VG
VG
VG
VG
-
8200YGI
8288
31N27
CX04319
835
57
57
58
58
60
M
M
M
M
M
VG
VG
VG
VG
VG
G
-
DKC69-72(RR2)
5518
N82-A7
58K22
V58Y41
57
60
59
60
57
T
M
L
L
T
VG
VG
VG
G
G
G
-
Hytest
Golden Acres
Southern States
SS
Pioneer
7887RR2
8311
842RR
894RR
31G98
59
61
58
59
60
T
M
T
M
M
G
G
G
G
G
G
G
-
AgraTech
Garst
Golden Acres
Vigoro
NK
919RR
8292YGI
8681FQ
Ex274001
N91-R9*
60
58
60
59
61
M
M
M
M
M
G
G
G
G
G
G
-
DeKalb
DeKalb
DeKalb
Croplan Genetics
Hytest
DKC67-60(RR2)
DKC69-71(RR2/YGCB)
DK 697
DS822RR
7930Bt
58
58
58
58
58
L
M
T
T
T
G
G
G
G
G
G
F
G
-
Croplan Genetics
NK
AgraTech
Greenwood
Dyna-Gro
872RR
NX8363
X41620RR
780
5515
59
58
59
59
60
M
L
M
T
M
G
G
G
G
G
F
F
Garst
Garst
Pioneer
Dyna-Gro
Greenwood
DeKalb
Dyna-Gro
NK
Dyna-Gro
Vigoro
Tifton, Georgia:
Mid-Season Corn Hybrids, 2004
Evaluations for Resistance to Insects and Other Traits
(Continued)
Company or
Brand Name
DeKalb
Hytest
Pioneer
NK
Croplan Genetics
Vigoro
AgraTech
AgraTech
Pioneer
AgraTech
Overall Resistance
to Insect Injury 2
2 or more
years
2004
Hybrid
Name
Days to
Antheses
Husk
Tightness1
DKC66-80(RR2)
TNT119
31G66
N83-N5
DS830
58
58
58
58
59
L
M
M
M
M
F
F
F
F
F
F
-
Ex284001
X41636RR
855RR
32D99
955RR
58
58
60
59
61
L
M
M
M
L
F
F
P
P
P
-
* White hybrid OR Full-season hybrid.
1. L = loose husks, M = medium-tight husks, and T = tight husks.
2. Overall insect resistance to ear-feeding insects (i.e., the corn earworm, the fall armyworm, the maize
weevil, and the pink scavenger caterpillar). The damage measured by the percentage of kernels
infested with the ear-feeding insects from five ears, where VG = very good, G = good, F = fair, P = poor,
and VP = very poor.