Georgia Agricultural Experiment Stations
College of Agricultural and Environmental Sciences
The University of Georgia

Research Report Number 668
November, 2000

Insect Screening Results

Evaluation of Corn Hybrids for Resistance to Insects

N. W. Widstrom

Environmental conditions in Georgia during the 2000 growing season were favorable for buildup of insect populations large enough to cause damage to corn. Generally, this damage is greatest in late-planted corn left in the field for an extended period past maturity.

It is recommended that hybrids resistant to insects be planted. These hybrids 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 0.5% to 6.6% and are reflected by VG, G, F, P, and VP ratings in the tables. Hybrids in the tests sustained average yield losses of 3.0%, and 3.9% in the full and mid-season, and short-season hybrid tests, respectively. The mean level of overall yield loss for all tests was 3.6%. Of the total loss, about 41% was attributable to ear injury by the corn earworm, 56% to the pink scavenger caterpillar, and 3% 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.

Both the hybrid tests (full and mid-season, and short-season) were planted April 26, 2000. Plantings were delayed in 2000 due to dry field conditions and cooler than normal temperatures. Plots were thinned to 20,000 plants per acre. Ratings for overall insect damage were completed during October.

Data for this section were compiled by J. M. Cook, J. C. Mullis, and C. A. Pearl 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, 2000
Evaluations for Resistance to Insects and Other Traits
  Overall Resistance to Insect Injury2
Company or Brand Name Hybrid Name Husk Tightness1 Days to Anthesis 2000 2 or more years
-
Southern States SS769Bt L 57 VG G
Pioneer 3245 M 57 G G
Funk's G 5510-A L 56 G G
Funk's G 5516 M 59 G G
AgriPro HS 9843 T 59 G -
 
Croplan Genetics 818 M 57 G -
Zimmerman Z37 M 59 G G
Pioneer 32K61 L 56 F G
Zimmerman 1851W M 59 F G
Croplan Genetics TR1106 L 58 F -
 
DeKalb DK679BtY T 59 F -
AgriPro AP 9707 M 59 F G
Croplan Genetics TR1166Bt L 58 F -
Garst 8251IT T 58 F -
Pioneer 3223 M 58 F F
 
Terra TR1157 T 58 F F
Garst 8285 T 60 F -
AgraTech 787 M 61 F -
Garst 8222IT M 58 F G
AgriPro HY 9646 M 59 F F
 
Croplan Genetics TR1089RR L 53 F -
Dyna-Gro X15550 M 57 F -
Funk's G 4581 M 60 P F
DeKalb DKC65-25 L 56 P -
Pioneer 31G98 M 58 P -
 
DeKalb DK 650 L 57 P P
Pioneer 34B23 L 54 P -
AgraTech 777 L 59 P -
Southern States SS729CL L 57 P -
Croplan Genetics TR1129RR L 54 P -
 
Pioneer 33G26 L 55 P P
Southland Genetics SG1580 M 60 P F
Pioneer 33J56 L 57 P P
AgraTech 770 M 60 P -
Grabow 01615 L 58 P -
 
Southland Genetics SG1611 T 58 P F
-
Asgrow RX764 L 53 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- and Full-Season Corn Hybrids, 2000

Evaluations for Resistance to Insects and Other Traits
  Overall Resistance to Insect Injury2
Company or Brand Name Hybrid Name Husk Tightness1 Days to Anthesis 2000 2 or more years
-
Southern States SS900Bt T 56 VG -
Greenwood 845 * M 62 VG VG
NK N91-R9 * M 58 VG G
Garst 8220 L 57 VG VG
NK N83-N5 L 58 VG G
 
Southland 00-01-MJ-19 L 59 VG -
AgriPro AP 9939 M 60 VG G
NK NX8349 M 57 G -
Southern States SS859CL M 56 G -
Croplan TR 702 E M 60 G -
 
NK N8811 M 56 G G
Greenwood 775 M 58 G -
AgriPro AP 9909 M 60 G F
Pioneer 3146 M 58 G G
DeKalb DK 687 M 56 G G
 
Pioneer 3163 M 58 F G
Southland 00-01-IJ-15 M 58 F -
Southland Genetics SG1701 M 59 F F
Pioneer 3085 * M 58 F G
NK NX7939 L 56 F -
 
Southern States SS78351 M 55 F -
Southland 00-01-MJ-20 L 59 P -
Southern States SS78406 L 58 P -
Pioneer 31R88 M 55 P -
Southland 00-01-IJ-14 L 56 VP -
 
DeKalb DK 697 L 56 VP P
-
* Full-season hybrid.
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.
Return to Table of Contents