The University of Georgia
GAES Research Report Number 657
November 1998

INSECT SCREENING RESULTS

Evaluation of Corn Hybrids
for Resistance to Insects

N. W. Widstrom

    Environmental conditions in Georgia are normally favorable for buildup of insect populations large enough to cause serious damage to corn.  Generally, this damage is greatest in late-planted corn left in the field for an extended period past maturity.

    Hybrids resistant to insects are recommended for planting and are presently the only economical means, in late plantings, for the reduction of damage by corn earworm, fall armyworm, maize weevil, and pink scavenger caterpillar.  Consult your local county agent and/or extension entomologist for additional control recommendations for other insects.

    Percent yield losses attributable to all insects for individual hybrids varied from 2.3% to 9.6% and are reflected by VG, G, F, P, and VP ratings in the tables.  Hybrids in the three tests sustained average yield losses of 6.0%, 6.1%, and 5.0% in the preliminary and full-season, mid-season, and short-season hybrid tests, respectively.  The mean level of overall yield loss for all tests was 6.1%. Of the total loss, about 44% was attributable to ear injury by the corn earworm, 47% to the pink scavenger caterpillar, and 9% to the maize weevil.  Losses to the pink scavenger caterpillar and maize weevil are based on damage by multiple generations of these insects as the corn dries in the field.  Timely harvest will substantially reduce losses to these two insects.

    Evaluations for resistance to corn earworm and fall armyworm, maize weevil, and pink scavenger caterpillar are given for hybrids in the tables following.  Lettered ratings refer only to relative resistance to insects and are not indicative of yield.  Thus, a hybrid rated poor for resistance to insects might possibly be among the highest yielders and vice-versa.  See the yield data in other tables for this information.

Husk tightness ratings were assigned using a scale of 1 to 5, in which 1 = very loose and 5 = very tight.  No average rating was less than 2.0 or greater than 4.0; therefore, only loose, medium, and tight ratings are given in the tables.

    Each of the three tests of hybrids (preliminary and full-season, mid-season, and short-season) was planted April 23, 1998.  Plots were thinned to 20,000 plants per acre.  Ratings for overall insect damage were completed during September.

Data for this section were compiled by J. M. Cook and J. C. Mullis of the United States Department of Agriculture, Agricultural Research Service, Insect Biology and Population Management Research Laboratory, and Georgia Coastal Plain Experiment Station, Tifton, Georgia.



Tifton, Georgia:

Short-Season Corn Hybrids, 1998

Evaluations for Resistance to Insects and Other Traits


Overall Resistance
    to insect injury2    
Company or
Brand Name
Hybrid
Name
Husk
Tightness1
Days to Anthesis 1998 2 or more years

 
Funk's G 5510-A M 56 VG G
Garst 8222IT M 55 G -
Pioneer 3245 M 56 G G
Pioneer 3223 T 58 G F
HyPerformer HS9843 M 57 G G
 
Gutwein 2696 L 58 G F
Pioneer 32k61 M 55 G G
Funk's G 5516 T 57 G G
NK N7931 M 56 G F
Terra TR1154 T 55 F F
 
DeKalb DK668 T 58 F F
Grabow 71593TC-S M ms F -
NK N73-N8 M 56 F -
Grabow 71593 M 57 F -
AgraTech 787 M 58 F F
 
AgraTech ATX770 M 56 F F
Funk's G 4581 M 57 F F
Grabow 71611TC3-S M ms F -
NK N7931 M 56 F -
Garst N5254 L 58 F -
 
HyPerformer HY9646 M 56 F P
AgriPro AP9707 M 57 P P
Garst 8396IT M 55 P -
Southland SS-5111 M 58 P -
NK N79-P4 L 55 P -
 
Asgrow RX913 M 58 P -
AgraTech ATX721 L 56 VP P
Pioneer 33G26 L 54 VP -
Southland SS-4115 M 56 VP -
HyPerformer HY9646 L 72 P -

1. L = loose husks, M = medium-tight husks, T = tight husks.
2. Overall resistance to insect injury evaluations were made on the basis of total percent damage to     the ear by one or more of the following insect categories:  corn earworm and fall armyworm, maize     weevil, and pink scavenger caterpillar.  Ratings were made on a scale from very good to very poor,     where VG = very good, G = good, F = fair, P = poor, and VP = very poor.


Tifton, Georgia:

Mid-Season Corn Hybrids, 1998

Evaluations for Resistance to Insects and Other Traits


Overall Resistance
      to insect injury2       
Company or
Brand Name
Hybrid
Name
Husk
Tightness1
Days to Anthesis 1998 2 or more years

 
NK N8811 M 56 VG VG
DeKalb DK706 M 56 G G
Pioneer 31B13 M 58 G G
Pioneer 3146 T 57 G G
Pioneer 3245S M 61 G -
 
NK N83-N5 M 58 G -
Pioneer 3167 M 58 G G
Terra TR1186 M 55 G F
Terra TR1185 L 56 F F
Mycogen 8460 L 58 F F
 
DeKalb DK687 T 56 F G
NK N83-R7 L 56 F F
Terra TR702E M 58 F G
Pioneer 3163 M 56 F F
Terra TR 1167 M 57 F F
 
AgriPro AP9939 M 57 F -
DeKalb DK683 M 56 F G
Vigoro V5970 M 58 F -
Mycogen 2815 M 56 F F
Southland SS-5119 M 60 F F
 
AgriPro AP9909 M 58 P P
Southland SS4120 M 57 P P
Mycogen 2888 M 57 P P
DeKalb DK679 M 58 VP -
Pioneer 31G20 M 55 VP P

1. L = loose husks, M = medium-tight husks, T = tight husks.
2. Overall resistance to insect injury evaluations were made on the basis of total percent damage to     the ear by one or more of the following insect categories:  corn earworm and fall armyworm, maize     weevil, and pink scavenger caterpillar.  Ratings were made on a scale from very good to very poor,     where VG = very good, G = good, F = fair, P = poor, and VP = very poor.


Tifton, Georgia:

Preliminary and Full-Season Corn Hybrids, 1998

Evaluations for Resistance to Insects and Other Traits


Overall Resistance
    to insect injury2    
Company or
Brand Name
Hybrid
Name
Husk
Tightness1
Days to Anthesis 1998 2 or more years

 
Greenwood 845 T 62 VG -
Wilson E7005 M 57 VG -
Asgrow XP8897 M 55 VG -
Greenwood 760 M 56 VG -
Southland SS8136* M 62 VG -
 
Galilee GIS982 T 59 G -
Wilson E3056 M 55 G -
Terra E1188 L 56 G -
Grabow 81570 M 56 G -
Southland EXP1498214 L 57 F -
 
Wilson E8051 M 57 F -
AgriPro AP9828 L 57 F -
AgriPro AP9829IMI L 56 F -
Pioneer 3085* M 57 F G
Grabow 81601 L 56 P -
 
Mycogen 2725 L 55 P P
Galilee GIS1007 M 58 P -
Southland EXP1497111 M 58 P P
Southland EXP1498116 L 56 P -
Wilson E5307 M 56 P -
 
Asgrow RX813 L 55 P -
Grabow 81581 L 55 P -
Grabow 81585 L 55 VP -
Asgrow RX810 L 55 VP -

1. L = loose husks, M = medium-tight husks, T = tight husks.
2. Overall resistance to insect injury evaluations were made on the basis of total percent damage to     the ear by one or more of the following insect categories:  corn earworm and fall armyworm, maize     weevil, and pink scavenger caterpillar.  Ratings were made on a scale from very good to very poor,     where VG = very good, G = good, F = fair, P = poor, and VP = very poor.
* Full-season hybrid.