SMALL GRAINS UPDATES
VARIETY RELEASESDr. J. W. Johnson, Department of Crop and Soil Sciences, Georgia Station, Griffin, GA 30223-1797.
The Small Grains Program announces the release of 'Fleming' wheat, 'Chapman' oat, and 'Wrens 96' rye. These varieties were developed jointly by the Georgia and Florida Agricultural Experiment Stations with support from State and Hatch funds. The names of Fleming and Chapman were selected to honor Dr. A. A. Fleming, former corn breeder and teacher of Genetics, and Dr. W. A. Chapman, former oat breeder and Center Director of the North Florida Research and Education Center at Quincy, FL.
Fleming wheat was tested under the experimental number GA 90078. It is an early maturing, medium height, strong straw variety with high yield potential when grown in the Coastal Plain region of the Southeast. Fleming also has an excellent test weight and resistance to powdery mildew and leaf rust.
Chapman oat was tested as FL874-E55. It is an early to medium maturity variety with excellent disease resistance. It is about 7 days later than FL 502 and about 5 days earlier than GA-Mitchell. It has a compact panicle, is relatively short in stature, and has very good lodging resistance. It possesses excellent resistance to crown rust.
Wrens 96 rye was tested under the experimental designation of WRC 7. It is a superior yielding variety for both forage and grain production, especially under high leaf rust pressure. In the absence of leaf rust pressure, Wrens 96 is equal to Wrens Abruzzi in forage yield. Under high leaf rust pressure, Wrens 96 will produce about 7 bushels more grain per acre than Wrens Abruzzi and FL 401.
Breeder's seed of Fleming, Chapman, and Wrens 96 will be maintained by the Georgia Agricultural Experiment Station. The Foundation class of seed of these three small grain varieties will be made available to seed growers in Georgia by Foundation Seed Development in 1997.
Other new wheat varieties now available are Coker 9663, Pioneer 2691, Jaypee, and AgriPro Mason.
DISEASESBarry M. Cunfer, Department of Plant Pathology, Georgia Station, Griffin, GA 30223.
The possibility that Karnal bunt might be present in Georgia and other southeastern states in 1996 could have resulted in a quarantine on southeastern wheat. This was perhaps the greatest threat ever to the crop in this region. Karnal bunt was found for the first time in the U.S. in Arizona in March, 1996. Spores similar to those of the Karnal bunt fungus were found at several locations in Georgia and neighboring states. No bunted kernels were found. These same type of spores were found on ryegrass seed in Oregon and subsequently in ryegrass seed from other countries around the world where Karnal bunt has not been found. Spores found on wheat seed in Georgia probably also came from ryegrass which occurs commonly in many fields. Research is in progress to confirm this. In the 1997 national survey, only bunted wheat kernels will be used to determine that Karnal bunt is present. Karnal bunt is a minor disease that can be controlled by standard crop management and seed certification programs. Efforts are being made to have USDA deregulate the disease.
The winter in Georgia was mild with a few cold periods which held powdery mildew in check. The disease was very low this season and caused very little damage. The season was early with warm weather in March resulting in very early heading dates. Some late maturing cultivars were slow growing due to inadequate vernalization. In Variety Test nurseries at Plains and Tifton where spores were abundant, susceptible late cultivars had severe leaf rust at jointing. A long cool and dry period set in through the grain-filling period of April and early May. This held back wheat leaf rust and oat crown rust in most areas of the state. Although leaf rust was common, it developed too late to cause much yield reduction. Oat crown rust was light in most areas of Georgia. Both leaf rust and crown rust were heavy in extreme south Georgia and at Quincy, Florida. In the State Variety test at Tifton where rust pressure was high, the average yield of 36 cultivars was increased 19.5% with two applications of fungicide. Leaf rust of rye was common but also developed late in the season in most fields. No stem rust was found at nursery sites and fields around the state. Losses to rusts were lighter than in most years.
Barley yellow dwarf (BYD) was prevalent throughout central and north Georgia in the spring. It caused moderate damage on several wheat varieties. There was considerable BYD on oats also. A comparison of the state wheat test at Tifton showed an improvement of bu/A over all entries where a foliar fungicide was used. The yield improvement was due primarily to control of leaf rust and leaf and glume blotch.
Prolonged rain during late May and early June just as wheat was mature resulted in considerable contamination of all small grains by "sooty molds" and other fungi. Most only cause seed surface discoloration, but others are pathogenic and will cause reduced germination and seedling vigor in planted seed. It will be especially important to treat seed with fungicides to improve seed germination rates and insure a good stand.
INSECTSG. David Buntin, Department of Entomology, Georgia Station, Griffin, GA 30223.
Relatively mild weather during the winter encouraged damaging insect populations to develop in small grains in 1996/1997. The Hessian fly, Mayetiola destructor, can cause extensive damage to winter wheat, triticale, and barley. Most wheat fields were planted with a resistant variety, and some fields were treated with an at-planting application of insecticide. However, Hessian fly infestations reached damaging levels in some fields in the southern part of the state. A new Hessian fly biotype (biotype L) was discovered near Griffin last spring and seems to be well established throughout northern Georgia. This biotype has not yet been found in southern Georgia, but it is only a matter of time before it spreads throughout the state. Biotype L can overcome virtually all the Hessian fly resistant varieties currently grown in the state. Consequently, I can no longer recommend resistant varieties for the entire state. The tables of Hessian fly infestations in entries of the wheat variety trial show that few varieties are highly resistant at Griffin. Because Biotype L constitutes only part of the Hessian fly population at Griffin, 'NK-Coker 9835', ‘NK-Coker 9663', 'GA-Stuckey', ‘Fleming', 'Hickory', 'Morey', 'Pioneer 2580', 'Pioneer 2628', 'Pioneer 2684', and 'Pioneer 2691' still showed some resistance at this location. Hessian fly infestations at Plains were low this year, but previously resistant varieties are still resistant at this location. Rye is still resistant and oat is immune to the insect. Both rye and oat are good Hessian-fly resistant alternatives to wheat for forage production.
The mild winter and dry spring encouraged large populations of aphids to develop throughout the state. Aphids caused direct feeding injury to small grains during head emergence and grain fill. Aphids also transmit barley yellow dwarf virus (BYDV) which can cause large yield reductions in wheat, oat, barley, and triticale. BYDV symptoms were present in moderate to high levels throughout the state and the disease caused considerable damage to wheat this season. At-planting insecticides such as DiSyston and Thimet can control aphids in the fall, and fields in some areas were treated specifically for aphid control and BYDV reduction using foliar insecticide applications.
The cereal leaf beetle now is established throughout northern Georgia and is present in the upper coastal plain (Sumter, Peach, & Washington Counties). 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 well below the treatment threshold of 0.5 larva or adult per stalk. However, damage was very evident in the northwestern region of the state with some fields needing treatment with insecticide. Cereal leaf beetle can be effectively controlled with a number of insecticides applied when larvae are active. 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 infestations in entries of the State Wheat Variety Trial at Plains, GA in spring of 1997.________________________________________________________________________ % Infested Immatures Entry stems per stem ________________________________________________________________________ ~ UGA 87467-E24 16.0 * 0.28 * FL Kucharek A28 16.0 * 0.21 * ~ Featherstone 520 16.0 * 0.21 * ~ Clemens 13.3 * 0.29 * AgraTech FFR 522W 12.0 * 0.32 * ~ Pioneer 2643 12.0 * 0.16 * ~ Coker 9803 12.0 * 0.13 * ~ Mason 6.7 0.07 ^ Madison 6.7 0.09 ^ Pioneer 2580 6.7 0.08 Coker 9704 6.7 0.09 ^ Morey 5.3 0.09 ~ Clemson 201 4.0 0.04 ~ Jackson 4.0 0.04 ~ Jaypee 4.0 0.04 Agripro Shelby 4.0 0.13 ^ Hickory 2.7 0.03 ^ Florida 304 2.7 0.03 Pioneer 2691 2.7 0.04 ^ UGA 87105-E43 2.7 0.03 ~ Hunter 2.7 0.08 Coker 9663 2.7 0.04 ^ GA Gore 1.3 0.01 ^ GA Dozier 1.3 0.01 AgraTech FFR 502W 1.3 0.03 ^ UGA 871339-E18 1.3 0.01 ^ Pioneer 2684 1.3 0.01 FL 92944RCX 1.3 0.01 ~ Clark 0 0 ^ Coker 9134 0 0 ^ Coker 9835 0 0 AgraTech EX096W 0 0 ^ Pioneer 2628 0 0 ^ GA Stuckey 0 0 ^ Fleming 0 0 FL 931839A5 0 0 UGA 89482-E7 0 0 UGA 881186-E48 0 0 UGA 881404-E56 0 0 UGA 881130-LE5 0 0 UGA 891283-LE18 0 0 Pocahontas 0 0 LSD 0.1 7.9 0.13 LSD 0.05 9.4 0.16 ________________________________________________________________________ * Indicates mean is significantly greater than zero (P < 0.1; LSD test). ~ Susceptible in previous trials. ^ Resistant in previous trials.
Hessian infestations in entries of the State Wheat Variety Trial at Griffin, GA in spring of 1997.________________________________________________________________________ % Infested Immatures Entry stems per stem ________________________________________________________________________ ~ Clemens 80.0 * 3.07 * ~ Coker 9803 60.0 * 1.67 * ~ Jackson 58.7 * 1.71 * ^ GA-Dozier 57.3 * 1.25 * Coker 9704 57.3 * 1.44 * ^ Pocahontas 54.7 * 1.16 * ~ Featherstone 520 53.3 * 1.67 * ~ Hunter 48.0 * 1.28 * ^ Coker 9134 42.7 * 0.91 * ~ Clark 42.7 * 0.99 * Agripro Shelby 42.7 * 0.95 * FL Kucharek A28 37.3 * 1.03 * ~ UGA 87467-E24 34.7 * 0.91 * UGA 891283-LE18 33.3 * 0.97 * ~ Mason 33.3 * 1.07 * AgraTech FFR 522W 32.0 * 0.65 * ~ Clemson 201 30.7 * 1.08 * ^ GA Gore 29.3 * 0.52 ^ Madison 29.3 * 0.52 ^ Florida 304 29.3 * 0.51 ~ Pioneer 2643 28.0 * 0.53 ~ Jaypee 26.7 * 0.59 * ^ Pioneer 2628 16.0 0.24 ^ Pioneer 2580 16.0 0.33 ^ Hickory 12.0 0.20 ^ Coker 9835 10.7 0.25 ^ Morey 10.7 0.21 ^ Fleming 9.3 0.27 ^ UGA 87105-E43 8.0 0.20 ^ Pioneer 2684 8.0 0.13 UGA 881186-E48 5.3 0.08 ^ UGA 871339-E18 5.3 0.08 Coker 9663 5.3 0.08 UGA 89482-E7 4.0 0.12 Pioneer 2691 4.0 0.09 FL 92944RCX 2.7 0.04 FL 931839A5 1.3 0.07 UGA 81404-E56 1.3 0.01 UGA 88130-LE5 0 0 ^ GA Stuckey 0 0 LSD 0.1 19.9 0.57 LSD 0.05 23.9 0.69 ________________________________________________________________________ * Indicates mean is significantly greater than zero (P < 0.1; LSD test). ~ Susceptible in previous tests. ^ Resistant in previous tests.