A Database for Triticeae and Avena
GEORGIA / FLORIDA
UNIVERSITY OF GEORGIA
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.
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
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
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
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.