VIRGINIA
VIRGINIA POLYTECHNIC INSTITUTE AND STATE UNIVERSITY
Department of Crop and Soil Environmental Sciences 1, Blacksburg, VA 240610404, USA.
J.J. Paling, C.A. Griffey, W.E. Thomason, J. Chen, J.A. Wilson,
D. Nabati, T.H. Pridgen, M.M. Alley, and E.G. Rucker.
J.J. Paling, C.A. Griffey, W.E. Thomason, and M.M. Alley.
Growing conditions. Although weather conditions in 2004 were more favorable for wheat planting, growth, and harvest than in 2003, grain yields and test weights were impacted by hot temperatures during the grain-fill period. Autumn temperatures were warm through October and into mid November during the planting season. Temperatures eventually declined and were colder than average and precipitation was slightly below normal for much of the state during the winter. Average daily temperatures through March 2004 were 5 degrees below normal for the entire state. Many small grain fields lacked optimal growth and tillering was poor in the early spring. Late planting, inadequate topsoil moisture, and especially the cold temperatures were contributing factors leading to delayed heading. Warmer, dry weather arrived in late April. The month of May was dry and warmer than normal for much of the eastern part of the state. Temperatures exceeded 85 F (29 C) on 19 days in May at the experiment station near Warsaw, VA. Similar hot and dry conditions were experienced throughout much of eastern Virginia during May, 2004. Despite later than normal heading, wheat ripened considerably earlier due to the high temperatures. Wheat harvest began ahead of schedule, but was delayed by rain and cloudy weather later in June.
Insects. Populations of the cereal leaf beetle and aphids attracted the attention of wheat producers in 2004. High numbers of aphids were found in wheat fields over most of the eastern wheat production area in late April. Scouting was advised to determine whether aphid populations had reached threshold control levels. Control measures were recommended when populations reached threshold and there was little activity of natural enemies in the field. Cereal leaf beetle populations reached economic threshold level later than usual in 2004 and persisted longer than anticipated. Highest populations and damage were reported in late-planted wheat fields having a low amount of foliage and in cover-crop fields. Scouting was recommended through mid May in untreated fields on the eastern shore.
Disease incidence and severity. Powdery mildew incidence and severity were lower than usual for the second consecutive year in the Eastern Shore and Coastal Plain regions because of excessive precipitation in 2003 and early and persistent hot May temperatures in 2004. Leaf rust incidence and severity were minimal in most of the wheat production area, but were moderate to severe on susceptible cultivars grown in research trials near Blacksburg. Barley yellow dwarf virus was low to moderate at Warsaw and Blacksburg. The incidence of FHB was much lower in 2004 than in 2003, when epidemics were widespread and severe.
Production. The Virginia Agricultural Statistics Service reported in January 2005 that Virginia wheat producers harvested 180,000 acres (72,900 ha) of winter wheat for grain in 2004, representing a 12 % increase over 2003. More than 85 % of the 210,000 acres (85,000 ha) of winter wheat planted was harvested for grain in 2004. Grain yields averaged 55 bu/acre (3,695 kg/ha) in 2004 and were 9 bu/acre (605 kg/ha) higher than the very low 46 bu/acre (3,090 kg/ha) average yield in 2003. Total 2004 wheat production for the Commonwealth was 9.9 x 106 bushels (269,380 metric tons).
State cultivar tests. A total of 80 entries were evaluated at seven locations across the Commonwealth in 2004. Included in this total were 37 released cultivars and 43 experimental lines (33 developed at Virginia Tech). Three white-seeded lines, one recently released by Virginia Tech, were among the 80 entries in the 2004 tests. Average grain yields ranged from 62 to 78 bu/acre (4,166-5,241 kg/ha) with an overall location and test average of 67 bu/acre (4,502 kg/ha). Wheat cultivars with yields significantly above the test average were USG 3209, SS MPV 57, 99176, USG 3706, SS 8308, USG 3592, and V9412. Seven experimental lines, six from Virginia Tech, also yielded significantly higher than the average. Yields of the highest producing cultivars and experimental lines ranged from 71 to 78 bu/acre (4,770-5241 kg/ha). Average test weights of wheat lines (based on seven locations across the state) ranged from 54.9 lb/bu (706 kg/m^3^) to 59.3 lb/bu (763 kg/m^3^) with a test average of 57.1 lb/bu (735 kg/m^3^). Out of the 26 entries with test weights significantly higher than the test average, 13 were released cultivars and 13 were experimental lines. Only two cultivars (SS 8308 and V9412) and three experimental lines (two from Virginia) had both grain yields and test weights significantly higher than the test average.
Virginia no-till test. All 80 wheat entries in the Virginia State wheat test were also planted no-till into corn stubble at the Eastern Virginia AREC near Warsaw, VA, in October 2003. Yields were 10-15 % lower than early season estimates based on late spring tiller and spike numbers. The combination of late heading and subsequent hot weather resulted in a shorter grain-fill period and earlier maturity and led to low yields and test weights, also observed in conventional-till tests at Warsaw. Grain yields averaged 59 bu/acre (3,964 kg/ha) with an average test weight of 57 lb/bu (733 kg/m^3^). The top-yielding cultivars produced more than 65 bu/acre (4,367 kg/ha) in 2004. Released cultivars yielding higher than the test average were SS MPV 57, SS 560, GA931233E17, 99176, Pioneer 26R15, Featherstone 520, USG 3209, and SS8302.
Virginia wheat yield contests. There were 11 entries
in the 2004 Virginia wheat yield contests. Seven of the entries
were grown no-till, three were conventional till, and one entry
was with minimum tillage. All of the contestants planted certified
seed treated with a fungicide. No-till yields of the 2004 entries
averaged slightly higher (2 bu/acre, 134 kg/ha) in 2004 than in
2003. The highest yield under no-till was obtained by George Floyd
III of Northampton County. George produced 100 bu/acre (6,719
kg/ha) of Coker 9835 wheat after soybean. Richard Sanford of Westmoreland
County entered two fields. Richard produced 86 bu/acre (5,778
kg/ha) of Tribute in one field and 85 bu/acre (5,711 kg/ha) of
SS 520 in another field. Frank Hula of Charles City produced 83
bu/acre (5,577 kg/ha) of Renwood 3260. Juan Whittington of Amelia
and Joseph Reamy of Richmond harvested 90 and 81 bu/acre, (6,047
and 5,442 kg/ha), respectively, of Sisson wheat. William Crossman
of Westmoreland grew 71 bu/acre (4,770 kg/ha) of Pioneer 26R24.
The most dramatic improvement in yield in 2004 versus 2003 was
for entries grown using conventional-till systems. Average yield
of entries in 2004 was 30 bu/acre (2,016 kg/ha) or 40 percent
higher than in 2003. Theo Haberland of Orange County had the highest
yield under conventional-tillage. His field of SS 520 yielded
103 bu/acre (6,921 kg/ha) grown after a previous crop of soybean.
In Northumberland County, Clifton Brann produced 93 bu/acre (6,249
kg/ha) and the team of Craig and Dan Brann produced 96 bu/acre
(6,450 kg/ha) of Tribute wheat after corn. Ronnie Russell of Middlesex
produced 82 bu/acre (5,510 kg/ha) of SS 550, which was the only
minimum tillage entry in 2004. Congratulations to all contestants
in the Virginia Wheat yield contest for producing excellent wheat
yields in 2004.
M.M. Alley, Soil Fertility and Crop Management.
Research on wheat management. A survey of the micronutrient content of Virginia wheat is being conducted to determine both the tissue and grain levels associated with major soils used for wheat production. Eight replicated field trials in the 2003-04 growing season found only three responses to micronutrient applications. Two sites produced higher yields with foliar applications of manganese while one site showed a positive response to foliar copper application. All responsive sites were on Coastal Plain soils (sandy texture) with pH values above 6.6. The nonresponsive sites had low levels of dilute acid extractable copper, manganese, and zinc (one field), but pH levels were less than 6.5. These results confirm that micronutrient deficiencies are associated with high soil pH levels and that dilute acid extractable levels of micronutrients are not well associated with crop response. The field trials and the survey of grain micronutrient contents will be repeated in the 2005 growing season.
W.E. Thomason, Small Grain Extension Specialist.
Research on bread wheat quality. Promising bread wheat cultivars have been planted in several management trials in the state. These cultivars are being grown with optimal nitrogen management practices. Seeding rate studies have been established in both yield trials and demonstrations. Seeding rates range from below optimum to above optimum (260 to 650 seeds/m^2^ or 15 to 35 seeds/row ft) and will be evaluated to determine appropriate seeding rates to optimize yield of bread wheat . Initial plant stands from two locations in the autumn 2004 are presented in Figure 1.
C. A. Griffey, J. Chen, J. A. Wilson, D. Nabati, T. Pridgen, and J. Paling
Fusarium head blight is a destructive disease of wheat and barley in the humid and semihumid production areas of the world (Schroeder and Christensen 1963). Scab epidemics have occurred in 26 U.S. states and five Canadian provinces and in the 1990s contributed to yield losses exceeding 500 x 10^6^ bushels (Rudd et al. 2001). Monetary losses due to FHB during the past decade have been valued at $3 billion (Van Sanford et al. 2001). Fusarium head blight epidemics in 1998 and 2003 devastated much of the SRWW crop in the mid-Atlantic region. Virginia has been no exception, with epidemic disease levels in 1998 causing losses estimated at 92,595 metric tons, at a value of $14.4 million (Griffey et al. 1999), reinforcing the need to accelerate development of FHB-resistant cultivars adapted to this region. Specific objectives implemented in the Virginia Tech Breeding Program are to: 1) identify and select FHB-resistant SRWW lines derived from traditional breeding populations; 2) identify and select FHB-resistant wheat lines derived from crosses between nonadapted lines with FHB resistance (type II in particular) and adapted lines possessing resistance to other diseases of economic importance; and 3) accelerate development of FHB-resistant lines using a combination of backcrossing, doubled haploid, and MAS breeding methods.To develop high yielding, FHB resistant SRW wheat lines, we have deployed a combination of topcross, doubled haploid, backcross, and molecular-marker assisted breeding methods (Tables 1 and 2). We first verified type-II resistance levels in FHB resistance sources currently used in breeding programs. Additionally, we characterized currently cultivated and adapted SRW wheat genotypes for FHB resistance or susceptibility. We found and confirmed high levels of type-II resistance in six wheat lines from China, three from Canada, one from France, and two from Japan (Chen et al. 2000). We also identified or confirmed the presence of tolerance to kernel infection, yield loss, and DON production in SRWW cultivars, such as Roane, McCormick, and Tribute (Wilson et al. 2003). Initially, we developed a doubled haploid line, VA01W-476, which expressed a high level of resistance in both greenhouse and field trials. This line has been used as a parent in many breeding programs in the eastern United States. We also have made great progress in the development of FHB-resistant lines using top-crossing and backcrossing methods. VA02W-713, a topcross (Ning7840/Pioneer2691//Roane) derived elite FHB-resistant SRWW line, ranked 1st in grain yield (77 bu/acre) among 54 entries in Virginia's 2004 Advance Wheat Test over three locations and will be evaluated in Virginia's Official Variety Trials in 2005.
| Tests | 2001 | 2002 | 2003 | 2004 | 2005 |
|---|---|---|---|---|---|
| Segregating Populations | 234 | 147 | 150 | 177 | 100 |
| Headrows | 4,000 | 4,400 | 7,600 | 6,500 | 3,600 |
| Observation Yield Plots | 50 | 61 | 50 | 266 | 359 |
| Preliminary Yield tests | 12 | 12 | 12 | 19 | 64 |
| Advanced, VA-State and Uniform Yield Tests | 12 | 18 | 14 | 18 | 14 |
| Total lines | Resistant no. lines (%) | Best lines no. (%) | Mean yield (bu/acre) | Mean index | Mean incidence (%) | Mean severity | |
|---|---|---|---|---|---|---|---|
| Adapted checks | 4 | 3 (75) | 81.6 | 1.4 | 49.8 | 2.8 | |
| Top-cross | 113 | 20 (18) | 5 (25) | 84.8 | 0.8 | 38.0 | 2.2 |
| Doubled-haploid | 31 | 9 (29) | 2 (22) | 80.8 | 1.1 | 37.5 | 3.0 |
| Backcross | 125 | 35 (28) | 19 (54) | 86.8 | 0.9 | 40.5 | 2.2 |
Type-II FHB resistance has been successfully transferred from diverse sources, such as Chinese wheat lines W14, Shaan85, Futai8944, Futai8945, Futai8946, Ning9016, Ning7840, Yumai 7, Er-Mai 9, and Wuhan 1, and the French line VR95B717, into adapted SRWW backgrounds Roane, Ernie, Pioneer 2684, Renwood 3260, Madison, Jackson, and a Sisson sib via backcrossing. Twenty-six SRWW lines possessing both high yield potential and FHB resistance were selected among 268 lines evaluated in Virginia's 2004 Scab Observation tests. These lines will be evaluated in 15 states as part of a collaborative research initiative in 2005. In addition, a set of NILs incorporating FHB resistance QTL from W14 and Futai 8944 into Roane and Ernie backgrounds have been developed using molecular-marker-assisted backcross breeding. Molecular markers in 3BS and 5AS QTL regions are being used to assist in the selection and breeding process. Haplotypes of the 3BS QTL and combinations of haplotypes of 3BS and 5AS QTL are being used to characterize FHB resistance in advanced wheat lines (Table 3).
References.