Wheat (Triticum
aestivum ‘Knudson’) S.
Halley,
Fusarium head blight; Fusarium graminearum G. Van
Ee, Dept. of Agricultural Engineering, Michigan State University, East Lansing, MI 48824 and V. Hofman, Dept. of Agricultural & Biosystems Engineering,
NDSU, Fargo, ND 58105
Spray Volumes, Spray Systems, and Orifice Orientation to
improve efficacy of JAU 6476 Fungicide to ‘Knudson’ HRSW, 2003
One of the most often asked
questions from producers is, ‘what spray volume should I apply fungicide for
control of FHB (Fusarium head blight)’? Results reported from research trials
on small grain suggest increasing volume increases coverage and infers increased
coverage improves fungicide efficacy. While this has been shown on many crops,
data on the improved fungicide efficacy based on increasing spray volume is
limited on small grains. A research study was conducted to evaluate spray
volume, sprayer systems, and orifice orientation to improve the efficacy of
fungicide for control of FHB. Cultivar ‘Knudson’ HRSW was planted for
evaluation in a field at the
A conventional nozzle system
uses pressure through a nozzle orifice to determine the drop size and pressure,
typically pressure pump, to deliver the drop to the target after passing
through a spray nozzle. The conventional system was equipped with spraying systems
XR8001 or XR8002 nozzles spaced 20 inches on center spraying at 40 psi. The
modified Spray-Air uses wind shear and wind speed technology to determine the
drop size and an air stream to deliver the spray solution to the target. The air
stream is generated by a centrifugal fan powered by a hydraulic pump. Speed is
increased or reduced by a flow control value and measured by a static pressure
gauge on the distribution tube. Static pressure was maintained at 25 psi. The advantage
of this system is that the air stream speed can be increased and the fine drops
can be carried a greater distance to the target. Wind does not affect the
delivery when the air stream speed exceeds wind speed. The Spray-Air system was
modified by adding a second set of orifices (.0424 gpm) spaced 10 inches on
center and oriented to spray the back side of the spike. The orifices were angled
30° downward from horizontal. A Spray-Air system typically has one row of
orifices angled 12° forward from vertical. Nozzle orientations were F + B
(forward + backward) both systems, forward (Spray-Air system), or vertical
(conventional system).
The spray volume was adjusted
by nozzle size on the conventional system and/or tractor speed. 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. Fungicide was
applied by a pressurized CO2 delivery system on 12 Jul at
The untreated had FHB
incidence and field severity levels of 53 and 5.8%, respectively. DON,
deoxynivalenol, levels on the untreated were 1.6 ppm. Visible FHB on treated
plots was negligible, < 0.5%, so levels were not recorded. Yield was
increased with the conventional spray system compared to the modified spray-air
system, 65.5 to 62.8 bu/A. This is in contrast to a field trial conducted in
2003 at the
Spray Volume |
Nozzle Orientation* |
Spray System |
Yield |
Test Weight |
(gpa) |
|
|
(bu/A) |
(lb/bu) |
5.2 |
Down |
Conventional |
67.0 |
60.7 |
5.2 |
Down |
Spray-Air |
61.0 |
60.7 |
5.2 |
F + B |
Conventional |
63.4 |
60.9 |
5.2 |
F + B |
Spray-Air |
61.2 |
60.6 |
|
|
|
|
|
19.2 |
Down |
Conventional |
66.2 |
60.8 |
19.2 |
Down |
Spray-Air |
65.7 |
60.5 |
19.2 |
F + B |
Conventional |
65.5 |
60.7 |
19.2 |
F + B |
Spray-Air |
63.4 |
60.5 |
|
|
|
|
|
Spray
volumes by orifice orientations averaged across spray systems |
|
|||
5.2 |
Down |
|
64.0 |
60.6 |
5.2 |
F + B |
|
62.3 |
60.8 |
19.2 |
Down |
|
66.0 |
60.6 |
19.2 |
F + B |
|
64.4 |
60.6 |
|
|
|
|
|
Spray
volumes by spray systems averaged across nozzle orientations |
|
|||
5.2 |
|
Conventional |
65.2 |
60.8 |
5.2 |
|
Spray-Air |
61.1 |
60.6 |
19.2 |
|
Conventional |
65.8 |
60.7 |
19.2 |
|
Spray-Air |
64.5 |
60.5 |
|
|
|
|
|
Nozzle
orientations by spray systems averaged across spray volumes |
|
|||
|
Down |
Conventional |
66.6 |
60.7 |
|
Down |
Spray-Air |
63.4 |
60.5 |
|
F + B |
Conventional |
64.4 |
60.8 |
|
F + B |
Spray-Air |
62.3 |
60.6 |
|
|
|
|
|
Spray
volumes averaged across nozzle orientations and spray systems |
|
|||
5.2 |
|
|
63.1 |
60.7 |
19.2 |
|
|
65.2 |
60.6 |
|
|
|
|
|
Nozzle
orientations averaged across spray volumes and spray systems |
|
|||
|
Down |
|
65.5 |
60.6 |
|
F + B |
|
63.3 |
60.7 |
|
|
|
|
|
Spray
systems averaged across spray volumes and
spray orientations |
|
|||
|
|
Conventional |
65.5 |
60.8 |
|
|
Spray-Air |
62.8 |
60.5 |
|
|
|
|
|
Untreated |
|
|
61.1 |
60.2 |
*Nozzle orientations were F + B (forward + backward) both systems, forward (Spray-Air system), or vertical (conventional system)
Spray Volume |
Nozzle Orientation |
Spray System |
Yield |
Test Weight |
gpa |
|
|
bu/A |
lb/bu |
GPA |
|
|
NS |
NS |
Orientation |
|
|
NS |
NS |
GPA*orient |
|
|
NS |
NS |
Sprayer |
|
|
2.4* z |
NS |
GPA*spray |
|
|
NS |
NS |
Dir*spray |
|
|
NS |
NS |
GPA*dir*spray |
|
|
NS |
NS |
C.V. % |
|
|
8 |
1 |
*Significant at 0.0308 probability level for mean comparisons