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SMALL GRAIN DISEASE SURVEY, 2001
Marcia McMullen, Phil Glogoza, Roger Ashley, Greg Endres, Jan
Knodel,
NDSU Extension Service, Plant Pathology Dept., Entomology Dept.
Dickinson REC, Carrington REC, and North Central REC, respectively
Purpose: The purpose of the small grain
disease survey was to determine the occurrence, distribution,
and severity of leaf and head diseases in North Dakota's wheat
and barley crops in 2001. Additional observations were made
of insect pests such as grasshoppers, grain aphids, cereal leaf
beetle and wheat stem maggot.
Methods: NDSU IPM field scouts were hired,
with supervision and direction from the Fargo Experiment Station
and from research extension centers at Dickinson, Minot and
Carrington. Field scouts were Nathan Carlson, Matthew Gregoire,
Jeanna Jambor, Kelly Novak, Jerry Schneider, and Holly Semler.
Fields were surveyed from early leaf stages through soft dough
stage of kernel development. Field scouts recorded district,
county, field location, crop, growth stage, previous crop, and
incidence and severity of major pests. Data was recorded on
hand held computers and transferred to the research extension
centers and the Fargo station. Data was summarized and analyzed
and weekly reports were provided to county extension staff and
to the public via the NDSU Crop and Pest Report.
Results: Approximately 1500 spring wheat,
durum, barley and oat fields were surveyed in 2001, with the
majority (958 or 64%) hard red spring wheat fields. Of the other
crops, 249 durum, 196 barley, 25 winter wheat and 30 oat fields
also were surveyed.
Leaf rust was detected in 22% of the 958 spring wheat
fields surveyed. The most frequent detections were in the south
central and central areas of North Dakota. The average severity
in infected fields was 8.5%; the average severity across all
fields was 1.9%. Leaf rust was not detected until July 5, in
LaMoure and Dickey counties. Leaf rust did not have significant
impact on yields in 2001, except perhaps for a few late planted
fields of susceptible varieties.
Tan spot was found frequently in spring wheat and durum
wheat and was the most common disease observed prior to heading
stages. For crops surveyed past heading, tan spot was found
in 54.7% of the spring wheats and 63.1% of the durum fields.
Tan spot severity on flag leaves of headed crops averaged 6.9%
in spring wheat and 7.5% in durum wheat. (See table).
Septoria leaf blotch was observed most frequently after
head emergence. Of fields surveyed past flowering stage, 78%
of the spring wheat fields had Septoria symptoms, 85.3% of the
durum, and 74.3% of the barley fields had symptoms. Average
severity on the flag leaf in infected spring wheat fields was
10.9%, in durum wheats was 18.9%, and in barley 6.0%. (See
table).
Scab (Fusarium head blight) was observed
in 70% of both spring wheat and durum wheat fields past the
flowering stage, and in 42.1% of barley fields. Average severity
of scab in spring wheats was 4.0% (range 0.1 - 34.2%), average
severity of scab in durum wheats was 7.2% (range 0.1 - 80%),
and in barley average severity was less than 1% (range 0.1-2.3%).
The most severe scab was found in the north central and northwest
districts and primarily in durum. (See table and Scab map).
Other diseases: Diseases such as flag smut and dwarf
bunt were NOT observed in the survey. The virus diseases, wheat
streak mosaic and barley yellow dwarf, were very infrequent,
as were black chaff and ergot. Loose smut was observed
in 43% of the headed barley fields, and severity ranged from
2 - 14%. Loose smut was found in 29.9% of spring wheat
fields, and severity ranged from 2 - 34%, with 2-4% most common.
SCAB
Crops were surveyed for scab from watery-ripe stage (Zadoks
growth stage 71) to mid-dough; information below is on these
surveyed fields
|
Crop
|
#
fields
|
%
fields with scab symptoms
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Average
fieldseverity in infected fields
|
Range
of severity in infected fields
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Average
field severity over all fields
|
|
HRSW
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254
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70%
|
4.0
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0.1-
34.2
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2.8
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|
Durum
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98
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70%
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7.2
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0.1
- 80.0
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5.2
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TAN SPOT and SEPTORIA IN FIELDS PAST THE
KERNEL WATERY RIPE STAGE:
|
Crop
|
#
fields
|
Tan
Spot% fields with symptoms
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Tan
Spot Average severity on flag leaf
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Septoria
% fields with symptoms
|
Septoria
Average severity on flag leaf
|
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HRSW
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254
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54.7%
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6.9%
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78.0
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14.2%
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Durum
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98
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63.1%
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7.5%
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85.3
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18.9%
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