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

2002-2003 Small Grain Performance Tests
Research Report Number 688
July 2003

INSECTS

G. David Buntin, Department of Entomology, Griffin Campus, Griffin, GA 30223.

The variety test was planted in the fall of 2002 at the Southwest Branch Experiment Station near Plains and was sampled for Hessian fly, Mayetiola destructor, infestations in early May 2003. A second test was conducted at the Bledsoe Research farm near Griffin, but infestations were too low for meaningful comparisons of varieties. Results of the test at Plains are shown in the next table. Varieties showing good levels of Hessian fly resistance were 'AGS 2000', 'Century', 'Pioneer 26R24', 'Pioneer 26R38', 'Pioneer 26R61', and 'NK-Coker 9835'. 'Croplan SR218' and 'SS 516' were resistant in last year's trials but were not included in this year's trial. 'Pioneer 2684', 'Roberts', and 'Fleming' contain resistance genes but are susceptible in Georgia and will not stand up to a heavy infestation. Varieties with good resistance in southern GA may not be resistant in northern GA because of the presence of biotype L in northern GA. Both rye and oats are good Hessian-fly resistant alternatives to wheat for forage production, because rye is highly resistant, and oats are immune to the insect.

Warm weather also encouraged aphid populations in the winter months throughout the state. Aphids caused direct injury to wheat and also transmitted barley yellow dwarf virus (BYDV), which caused losses in some areas. Although the level of expression of symptoms varies between varieties, no varieties are truly resistant or tolerant of BYDV infection. Systemic insecticide seed treatments and properly timed foliar applications of insecticides can greatly reduce aphid numbers and minimize BYD incidence.

The cereal leaf beetle now is established throughout northern and most of southern Georgia. Populations continue to increase and caused noticeable damage this year in the coastal plain region. Larvae and adults are present in the spring during grain filling where they remove the upper leaf surface and chew elongated holes in leaves. Populations in most areas still are below the treatment threshold of 0.5 larva or adult per stalk. However, damage was very evident in the northwestern and central Piedmont regions of the state as well as the upper coastal plain from Milledgeville to Statesboro with some fields needing treatment with an insecticide. Cereal leaf beetle can be effectively controlled by a number of insecticides when applied to active larvae. Consult your local county extension agent for a list of recommended insecticides for this insect and for management practices for other insect pests of small grains.

Hessian fly infestations in entries of the Georgia State Winter Wheat Variety Trial at Plains, GA , late-planted in 2002-2003.
Entry % infested
plants
Hessian Flies
per plant
SS524 40 0.65
NK Coker 9663 35 0.60
VA98W-706 35 0.40
Fleming 30 0.75
SS535 30 0.60
NK B950943 30 0.50
NC98-26143 25 0.60
AgriPro D99*5725 20 0.45
USG 3209 20 0.40
SS520 20 0.40
AGS 2485 20 0.25
Pioneer 26R58 20 0.20
Roberts 15 0.75
GA931470E62 15 0.35
AgriPro Savage 15 0.25
Croplan Genetics 514W 15 0.15
GA931630E48 10 0.15
GA951216-2E26 10 0.15
UGA931233E17 10 0.10
Pioneer 26R12 10 0.10
GA95652-2E56 10 0.10
AgriPro Crawford 5 0.10
GA951079-2A25 5 0.10
UGA931266A31 5 0.05
GA94261E7 5 0.05
AgriPro L96*9266-1 5 0.05
GA961662-2E22 5 0.05
GA951216-2E14 5 0.05
AGS 2000 5 0.05
Pioneer 26R61 0 0
Pioneer 26R24 0 0
NC Neuse 0 0
NK Coker 9152 0 0
GA90552AE33 0 0
GA931241E16 0 0
GA93052E42 0 0
GA931587E53 0 0
Vigoro Tribute 0 0
Pat 0 0
McCormick 0 0
NK B960457 0 0
GA941208-2E35 0 0
GA 951395-2E19 0 0
GA951079-2E31 0 0
GA931233-2E7 0 0
GA961565-2E46 0 0
GA941208-2A27 0 0
Entry values from a non-replicated trial.