2001-2002 Small Grain Performance Tests
The Georgia Agricultural Experiment Station
College of Agricultural and Environmental Sciences
The University of Georgia
Research Report Number 682
SMALL GRAIN UPDATES: Insects
G. David Buntin, Department of Entomology,
Warm weather in January and February followed by severe freezes in March and dry weather in April injured wheat thereby reducing grain yield and quality. Warm weather also encouraged infestations of the Hessian fly, Mayetiola destructor, in susceptible varieties in some areas during the 2001-2002 season. The variety test was planted in the fall at the Southwest Branch Experiment Station near Plains and was sampled for hessian fly infestations in late January. A second test was conducted at the Becham Research Farm near Griffin but infestations were not consistent enough 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', 'Pioneer 26R24', 'Pioneer 26R38', 'Pioneer 26R61', 'Pocahontas', 'Roane', and 'NK Coker 9835'. 'Roberts' has been resistant in the past trials but rated as moderately susceptible in this trial. 'Croplan SR218' and 'SS (FFR) 516' were resistant in last year's trials but were not included in this year's trial. 'Pioneer 2684' 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. 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 fall and winter months throughout the state. Consequently, infection levels by barley yellow dwarf virus (BYDV) which is transmitted by aphids, causes 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 BYDV 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
|NK Coker B950943||S||48.9*||0.89*|
|NK Coker 9803||S||47.8*||1.27*|
|NK Coker 9663||S||40.0*||1.08*|
|NK Coker 9152 (NK BL940582)||S2||10.0||0.18|
|Crawford (UGA 91426E39)||R||8.9||0.18|
|NK Coker 9835||R||5.6||0.09|
|1. S = susceptible, MR = moderate resistant, R = resistant.|
2. This entry was susceptible in previous trials.
* Mean is significantly greater than zero (P < 0.05; LSD test). Entry means average of 3 replications, RCBD.
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