Items from the United States - Georgia / Florida.



Department of Agronomy, Griffin, GA 30212, USA.

J.W. Johnson, R.D. Barnett, B.M. Cunfer, and G.D. Buntin.

The 1999 Georgia winter wheat crop was grown on about 250,000 harvested acres, which was the lowest in 20 years, and resulted in a state average yield of 44 bu/acre. Acreage was down because of the lowest prices in 30 years. Overall, the season was characterized by a mild and wet winter followed by a dry and hot spring. Some cultivars had vernalization problems because of the warm autumn and winter and the delayed planting. Cool and dry conditions prevailed through the grain-filling stage. Septoria glume blotch and leaf rust also were major factors in some low yields. Hessian fly infestations reached damaging levels in some parts of the state. Cereal leaf beetle also reached damaging levels this year, which resulted in several thousands acres being sprayed.



Wrens 96, PI 602997, is a winter rye that was developed at the University of Georgia Agricultural Experiment Station in coöperation with the USDA-ARS and Florida Agricultural Experiment Station and released in 1996. Wrens 96 was derived from a recurrent phenotypic selection procedure initiated to improve forage yield of Wrens Abruzzi rye. The selection procedure included visual selection of spaced plants, grid selection, maintenance of relatively large population size, biparental selection, a 1-year cycle interval, and intermating of selected plants in isolation. Wrens 96 is a high-yielding, early-maturing cultivar for the Coastal Plain region of the southeast for both forage and grain production. Wrens 96 has medium-strength straw and is similar in plant height, test weight, and winter hardiness to Wrens Abruzzi.

The SRWW line GA 89482 was released as an exclusive cultivar. GA 89482 was selected from the cross 'Pioneer 2555/PF 84301//FL302' and has the T1B·1R translocation. This cultivar possesses excellent resistance to powdery mildew, moderate resistance to leaf rust, and good resistance to Hessian fly. GA 89482 has excellent test weight and straw-strength and is medium in maturity.


Plant pathology.

Accurate identification and distribution of the ryegrass bunt fungus, T. walkeri, in the southeastern U.S. confirmed that teliospores on wheat seed had been misidentified as T. indica, the causal agent of Karnal bunt and a quarantined disease in the U.S. This identification helped to prevent a quarantine on wheat in the region. Karnal bunt has not been found in the southeastern U.S.

A review paper on the precise classification of Septoria and Stagonospora fungi on cereals contributes to more accurate disease-management strategies. The paper discusses the relationship among this group of fungi on cereals based on classical and molecular taxonomic techniques.



The damage-yield loss relationships of Hessian fly in SRWW were examined over a 9-yr period with various cultivars and planting dates at various locations. Grain yield loss increased linearly with increasing percentage of autumn-infested tillers and spring-infested stems. Infestations had little effect on grain test weight until infestations exceeded 20 % of autumn-infested tillers or 38 % of spring-infested stems. Economic damage occurred when autumn infestations exceeded 5-8 % of infested tillers or when spring infestations exceeded 13-20 % of infested stems or 0.4-1.0 immature per stem.

The cereal leaf beetle, Oulema melanopus, was first discovered in the late 1980s and is now occurring throughout the northern two-thirds of Georgia and Alabama. Larvae can cause extensive defoliation during grain heading in winter wheat. Cereal leaf beetle cannot be controlled reliably by manipulating planting date or variety maturity, and plant resistance is not available in southern wheat varieties. Averaged over all trials, yield reductions have ranged from 0 to 8+ bu/acre. Most labeled insecticides are effective at killing larvae at low rates. However, the B. thuringensis (Bt) product Mtrak did not effectively control larvae. Only lambda cyhalothrin (Karate 1E/Warrior T) consistently provided season-long control with a single application when applied during egg laying before final egg hatch. Lambda cyhalothrin also controls aphids, and because it can be applied during egg laying, often can be tank mixed with foliar fungicides for leaf rust suppression.



  • Bruckner PL, Johnson JW, Burton GW, Gates RN, Barnett RD, and Hill GM. 1999. Registration of 'Wrens 96'. Crop Sci 39:287.
  • Buntin GD. 1999. Hessian fly injury and loss of winter wheat grain yield and quality. J Econ Entomol 92:1190-1197.
  • Cunfer BM and Johnson JW. 1999. Soft red winter wheat resistance to S. nodorum and other foliar pathogens. In: Internat Workshop on Stagonospora Diseases of Cereals 5:159.
  • Cunfer BM and Ueng PP. 1999. Taxonomy and identification of Septoria and Stagonospora species on small grain cereals. Ann Rev Phytopathol 37:267-284.
  • Cunfer BM and Castlebury LA. 1999. Tilletia walkeri on annual ryegrass in wheat fields in the southeastern United States. Plant Dis 83:685-689.
  • Cunfer BM. 1999. Stagonospora and Septoria pathogens of cereals - the infection process. In: Septoria and Stagonospora diseases of cereals: a compilation of global research, Proc 5th Internat Workshop on Septoria/Stagonospora Diseases of Cereals. CIMMYT, Mexico D.F. pp. 41-45.