UTAH STATE UNIVERSITY
Plant Science Department, Logan, UT 84321, USA.
Spring wheat.
R.S. Albrechtsen.
Production, diseases. and insects.
A larger 1995 harvested spring wheat acreage in Utah, compared
to that of 1994, coupled with a 63 % higher yield per acre (75
bushels vs 46 bushels) resulted in a production nearly double
that of the previous year, and the highest total for many years.
An unusually wet spring and early summer caused some difficulties
in planting the crop and spraying weeds, but eventually resulted
in a very good crop overall.
Spring wheat diseases were generally light. Losses
from the Russian wheat aphid and the cereal leaf beetle were spotty,
but generally minor.
Breeding Program. We
continue to identify improved cultivars from the Western Regional
Spring Wheat Nursery and from other breeding programs in the west.
Cultivars. Rick (HRSW),
released from our program, continues to perform well under both
irrigated and nonirrigated conditions. Sylvan (HRSW), released
jointly with Colorado, performed well in 1995 tests.
D.J. Hole.
Production, diseases, and insects.
1995 harvested acreage of winter wheat was 140 thousand acres,
down 10 thousand acres from 1994. Average yields were 10 bu/acre
higher at 50 bu/acre, resulting in production of 7 million bushels,
up 1 million from 1994.
Some natural infections of dwarf bunt occurred,
although resistant cultivars continue to hold that disease in
check. The wet, cool spring resulted in various foliar diseases
that had minimal yield impact. Cereal leaf beetle infestations
were light, as were Russian wheat aphid infestations.
Breeding program. Breeder
seed was harvested for UT1650-150 (tested in the regional nurseries
as UT000150). UT1650-150 was approved for release by the Utah
Agricultural Experiment Station under the name `Utah-100'
commemorating the 100th anniversary of Utah statehood. Breeders
headrows were planted for a hard white winter wheat that has been
tested under the designation UT1944-158.
Cultivars. Utah-100 will
replace Promontory in some areas with limited moisture, otherwise
Promontory and Manning continue as the most widely-grown dryland
cultivars. Garland, our most recent released cultivar for irrigated
areas, continues to increase in acreage.
Publications.
Albrechtsen RS, Hole D, Thompson VD, and Clawson
SM. 1995. 1994 Utah small grains performance trials. UAES report
152.
Hole D, Dewey W, and Albrechtsen RS. 1995. Registration
of `Promontory' Wheat. Crop Sci 35:1206-1207.
Hole D, Albrechtsen RS, and Clawson SM. 1996. Registration
of `Garland' Wheat. Crop Sci 36:208.
VIRGINIA POLYTECHNIC INSTITUTE AND STATE UNIVERSITY
Departments of Crop and Soil Environmental Sciences; Plant Pathology, Physiology and
Weed Science; and Human Nutrition and Foods; Blacksburg; VA
24061; USA.
Carl A. Griffey and Dan E. Brann (Department of Crop and Soil Environmental Sciences) Erik L. Stromberg (Department of Plant Pathology, Physiology and Weed Science), Janet M. Johnson and Carolyn H. Harris (Department of Human Nutrition and Foods).
Virginia wheat production in 1995.
C.A. Griffey and D.E. Brann.
Growing conditions. The
1994-95 growing season was drier than normal during the
period from September through April, with January being the only
month in which precipitation was above normal in all areas, except
the Tidewater region. Precipitation was above normal during May
and June. Frequent showers occurring on June 3, 4, 6, 7, 12-14,
and 22-30 caused considerable delays in harvest and resulted
in reductions in test weight and grain quality. Temperatures
were below average during September and October, above average
from November through January, below normal during February, above
average during March, and predominantly normal from April through
June. During the period from 2-7 January, minimum temperatures
ranged from 8-20_F. The growing season generally was mild,
and winterkill was not significant.
Production. According
to the Virginia Agricultural Statistics Service, 300,000 acres
(121,500 ha) of soft red winter wheat were planted in Virginia
in 1994, with 275,000 acres (111,375 ha) being harvested for grain.
An average yield of 64 bu/acre (4,300 kg/ha) was obtained in
1995, which was 7 bu/acre higher than the previous state record
set in 1992. Total wheat production in 1995 was 17.6 million
bushels (479,424 metric tons).
Virginia wheat yield contests.
Eleven wheat producers representing nine counties participated
in the 1995 Virginia Wheat Yield Contest. Louis and Randolph
Aigner of Henrico County had the highest-yielding wheat at 143
bu/acre (9,608 kg/ha) over a minimum area of 3 acres (1.2 ha).
Ten of the 11 producers had grain yields of 103 bu/acre (6,920
kg/ha) or higher. Three producers in different counties participated
in the Virginia No-Till Wheat Contest. David Hula of James City
County had the highest-yielding wheat at 135 bu/acre (9,070 kg/ha)
over a minimum area of 3 acres (1.2 ha). The other producers
had yields of 92 and 102 bu/acre (6,180-6,850 kg/ha).
State cultivar tests.
Eight public and 24 private wheat cultivars were evaluated at
six locations in Virginia in 1995. The cultivars Pioneer 2580
(with Baytan seed-treatment), Jackson, and Pioneer 2684 (Baytan-treated)
were the highest yielding, with average yields of 89, 84, and
82 bu/acre (5,980-5,510 kg/ha), respectively. Other cultivars
with average yields ranging from 80 to 75 bu/acre (5,375-5,039
kg/ha) and not significantly different from the overall cultivar
mean were Baytan-treated Pioneer 2691, 2548, and 2643; Wakefield;
and FFR 555W; and Vitavax-treated Coker 9835, GA-Gore, Coker
9803, Madison, Hickory, Elkhart, and Coker 9904. Test weight
means for the six locations ranged from 54.2 at Blacksburg to
60.0 lb/bu (698-772 kg/cu m) at Warsaw, Virginia, with
a mean of 56.7 lb/bu (698 kg/cu m) over all locations. At Warsaw,
where the crop was harvested on time and prior to frequent rains,
test weights ranged from 57.8 to 62.1 lb/bu (744-799 kg/cu
m). Cultivars with average test weights of 58.0 lb/bu (746 kg/cu
m) or higher over locations were Succession, Hoffman 89, Coker
9803, Coker 9474, Pioneer 2684, Saluda, and Elkhart.
Disease incidence and severity.
Powdery mildew development was initiated later than normal, and
severities were generally moderate. As normally observed, leaf
rust developed late in the season with moderate severity on flag
leaves. Septoria leaf blotch and glume blotch were prevalent
and moderately severe as a result of frequent rains during May
and June. Because of warm autumn temperatures, barley yellow
dwarf was prevalent and resulted in considerable stunting of plants
in most cultivars. In winter durum tests grown at three locations
in western Virginia, scab was severe and resulted in a considerable
reduction in grain quality.
Wheat management: challenges for 1996.
Because of extended wet conditions in the autumn of 1995, thousands
of wheat acres were planted late to very late in the mid-Atlantic
region. Wheat development also was reduced because December temperatures
were 4-6 degrees colder than normal across Virginia. Many
of these wheat fields were just emerging or only had one leaf
by early January. Ideally, wheat should be at the 2- or 3-tiller
stage by early January to produce maximum yields. Wheat that
was just emerging in early January should receive sufficient heat
units to produce at least one additional productive tiller per
plant by the jointing stage in early April. Wheat with 40-50
heads/sq ft can produce at least 50 bu/acre. On late planted
fields, producers should estimate potential yields with normal
weather and timely management of nutrients and plant protection.
Nitrogen rates should be determined based on tiller development
and yield potential for each field.
Control of barley yellow dwarf in Virginia wheat production.
E.L. Stromberg.
Barley yellow dwarf is the most widely distributed
and destructive virus disease of cereal crops in the world. Each
year this disease is present to some degree within Virginia's
wheat crop. Symptoms of the disease are often ambiguous and can
be overlooked by producers and/or their advisors as nutritional
or environmental disorders. The barley yellow dwarf virus is
identified tentatively by the occurrence of groups of yellowed
and often dwarfed plants. Later leaf discoloration in shades of
yellow, red, and purple is evident, especially from the leaf tip
to base from leaf margin to the midrib. Definitive diagnosis
of the causal agent requires serological testing.
The barley yellow dwarf virus consists of polyhedron
viron that range from 21-26 nm in diameter. The virus
particles are restricted to the phloem of the host and occur in
extremely low numbers, making definitive diagnosis with the electron
microscope difficult.
This virus is known to be transmitted by more than
20 species of aphids. The most important in Virginia are the
corn leaf, English grain, and the oat bird-cherry aphids. The
barley yellow dwarf virus complex consists of a number of strains
or variants that differ in their virulence, host range, and vector
specificity. Over 80 species of grass family plants are known
hosts, including barley, rye, oat, wheat, corn, and fescue. This
virus complex consists of one or more of the five prominent strains
(MAV, PAV, RMV, RPV, and SGV) with the PAV strain occurring most
commonly in Virginia. Given the wide host range and number aphid
species able to transmit the virus, it is not surprising that
this disease is the most commonly occurring cereal virus in Virginia.
Epidemics of barley yellow dwarf are most likely
to occur during mild autumn and winter seasons that favor grass
and small grain growth, as well as aphid movement and migration.
Flights of the aphid-vector can be localized, or when favored
by weather that produces low-level jet winds, can cover hundreds
of miles. The feeding activity of the aphids and virus transmission
can occur at any time during the life of the wheat crop, but autumn
infections are the most damaging.
Research conducted at Warsaw, Virginia, in 1992
and 1993, has documented the loss in grain yield from autumn infections
of barley yellow dwarf in the cultivar Wakefield at 30-33
%. Loss in yield is attributed to reduced number of grains per
head and reduction in 1,000-kernel weight (or plumpness). This
indicates that a 25 % incidence of autumn infection by barley
yellow dwarf will result in a 7.5-8 % reduction in grain
yield. With a 90 bu/acre yield potential, that means a 6.75-7.2
bu/acre loss, or $22.00-25.00 per acre.
At present, no high level of resistance to barley
yellow dwarf occurs in soft red winter wheat cultivars. The only
means of attempting to control this disease has involved avoiding
early planting and/or application of an insecticide at planting
to control aphid infestation that may occur.
Control of the aphid vectors of barley yellow dwarf
is not always timely or effective, and the materials presently
available for aphid control are highly toxic. Aphids carrying
the virus require only 20 to 30 minutes of feeding to transmit
barley yellow dwarf. Aphids do not have to remain long within
a wheat field to transmit the disease.
Research over the last several years in Virginia
with an experimental seed treatment material called `Gaucho'
(Gustafson) or NTN338 (Bayer) has shown remarkable efficacy in
preventing fall barley yellow dwarf infections in both wheat and
barley. The material is systemically active within the seedling
wheat and acts as a feeding inhibitor to the aphids. Once aphids
begin feeding on treated plants, they stop feeding and either
die or move on without transmitting the virus. In 1994-95 season,
Wakefield wheat was treated with four different rates of Gaucho
480F ranging from 0-2.0 fl oz of product per hundred pounds
of seed. Plots were seeded in seven 7-inch spaced rows that were
22 ft long, and treatments were replicated four times. Fall infections
of barley yellow dwarf were extremely heavy in untreated plots
representing as much as 30 % of the plot area affected. The 1.0,
1.5, and 2.0 fl oz rates provided nearly season-long protection
from barley yellow dwarf and grain yields were significantly higher
than the untreated plots (see Table 1).
Table 1. Effect of Gaucho insecticide seed-treatment on grain yield and incidence of barley
yellow dwarf virus in plots of Wakefield wheat in 1994-95.
_____________________________________________________________________________
Yield Barley yellow dwarf
Treatment bu/acre Grain plumpness infected plant loci
fl oz per at 13.5 % 1,000-kernel wt per plot at Zadoks
100 lbs seed moisture grams growth stage 37
_____________________________________________________________________________
Untreated control 98.2 37.33 2.33
Gaucho 480F @0.5 oz 102.6 37.48 2.08
Gaucho 480F @1.0 oz 106.4 38.58 0.33
Gaucho 480F @1.5 oz 116.1 38.68 0.00
Gaucho 480F @2.0 oz 114.3 38.55 0.00
_____________________________________________________________________________
Gaucho was registered this past season for use in
small grains for control of barley yellow dwarf and aphids and
has proved highly effective in trials conducted by me and others
over the past several years in Virginia and other states. Gaucho
offers an environmentally acceptable means to control autumn infections
of barley yellow dwarf with a seed treatment.