�Knudson� HRSW Response to JAU 6476 Fungicide Rate,
A new fungicide JAU 6476,
prothioconazole, has shown improved efficacy in the control of Fusarium head
blight on durum and hard red spring wheat and reductions in deoxynivalenol levels
compared to most of the currently labeled fungicides on small grains. Research
is needed so growers will know the consequences of different rates under
different environmental conditions and infections from different causal
organisms. Cultivar �Knudson� HRSW was planted for JAU 6476 fungicide rate
evaluation in a field at the LangdonResearchExtensionCenter in spring 2003. An area was planted with a Melroe
double-disk grain drill, disks spaced 6-inches apart on 3 May. The area was
divided to plots 12 ft. wide by 20 ft. long in a randomized complete block
design with six replicates. Recommended production practices for Northeast
North Dakota, NDSU Extension, were followed. Wheat grains colonized by F. graminearum were hand broadcast on 19
Jun on individual plots at 3.5 oz per plot to increase chance of infection to
Fusarium head blight. Treatments and JAU 6476 rates were: 1) Untreated. 2)
0.125x (0.7 fl. oz/A). 3) 0.25x (1.4 fl oz/A). 4) 0.5x (2.85 fl oz/A). 5) 1x
(5.7 oz/A). 6) 2x (11.4 fl oz/A). 7) 3x (22.8 fl oz/A). Treatments were applied
by a modified SPRAY-AIR� tractor sprayer. The sprayer was modified to
distribute the solution from orifices angled 30 degrees downward from
horizontal and oriented forward and backward to maximize spike coverage. The
solution carrier was pressurized CO2 delivering 19.2 GPA into the
air stream through metering orifices on 14 Jul at The tractor traveled on the left half of the plot
area. This area also provided border to reduce off target drift between
treatment areas. Visual estimation of Fusarium head blight (FHB) incidence and
field severity, 20 samples per plot, summation of (spikelet count per
individual head multiplied times FHB infected spikes per head) and flag leaf
necrosis, 5 samples per plot, were counted on 30 July. A flag leaf necrosis
sample was one leaf and a head sample was one spike. Each plot was harvested
with a Hege plot combine on 19 Aug and the grain sample cleaned and processed
for yield and test weight measurement and deoxynivalenol determination. Data
was analyzed with the general linear model (GLM) in SAS. Least significant
differences (LSD) were used to compare means at the 5% probability level.
Disease levels were extremely
low with Fusarium head blight incidence and field severity on the untreated at 36
and 2.3%, respectively. Fusarium head blight incidence was reduced by a 1x and
3x fungicide application. A 0.5x fungicide application reduced disease levels
from the untreated. No differences in Fusarium head blight field severity, yield,
and test weight were determined. All fungicide applications reduced
deoxynivalenol compared to the untreated. Levels were also reduced by the 0.5x
rate compared to smaller rates and a 3x rate compared to 1x and lower rates.
Deoxynivalenol levels were significantly correlated with treatment -0.795.
Treatment* �and rate
0.125x 0.7 fl oz��..
0.25 x 1.4 fl oz...........
0.5 x 2.85 fl oz...........
1.0 x 5.7 fl oz���.
2.0 x 11.4 fl oz...........
3.0 x 22.8 fl oz...........
*JAU 6476 (480 SC) applied with
Induce Adjuvant at 0.125% v/v/A.