comparison of venturi spray tips and spray pressure on glyphosate and paraquat efficacy
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Kansas State University Biological and Agricultural Engineering Department
Comparison of Venturi Spray Tips and Spray Pressure on Glyphosate and
Paraquat Efficacy
Robert Wolf Biological and Agricultural Engineering Dept.
Cathy Minihan and Dallas Peterson Department of Agronomy
Kansas State University Biological and Agricultural Engineering Department
Objective of this study:
Compare the efficacy and spray droplet characteristics of three venturi flat-fan nozzles against the turbo flat-fan tip at 207, 345, and 482 kPa (30, 50, and 70 psi).
Kansas State University Biological and Agricultural Engineering Department
Materials and Methods:Experiments: Location: Ashland Bottoms, Manhattan, KSExp. Design: 2 x 3 x 4 split-split plot with 3 reps (24 treatments)Drop Collectors: Placed in 2 reps with 2 cards per rep (96 cards)Plot Size: 3 x 9 m with 1.5 m bufferWeeds Velvetleaf, common sunflower, sorghum, cornVisual Ratings: 1, 2, and 4 weeks after treatment
Herbicides (2): Paraquat, 0.487 lb ae/a (1.3pt/a), NIS @ .25% v/vGlyphosate, 0.28lb ae/a (12 oz/a), AMSU @17 lb/100
gal
Application Conditions: Date: July 09, 2002 Weed Size: Vele - 15 cm, Cosf - 20 cm, Sorg – 25 cm, Corn – 13 cm Temperature: 37 C R. H.: 20% Wind: S-SW@ 4-5 km/h
Kansas State University Biological and Agricultural Engineering Department
Spray Tips (4):Turbo Flat-fan (TT)Air Induction Flat-fan (AI)Ultra lo-drift (ULD)Air Mix (AM)
Spray Volume: 94 L/ha (11002 orifice tips)Application Ground Speed: 5.5, 7.1, and 8.4 km/hSpray Pressure: 207, 345, and 482 kPaSpray Tip Spacing: 76 cm, tilted 15 degreesCanopy Boom Height: 51 cm
Materials and Methods cont.:
Kansas State University Biological and Agricultural Engineering Department
Collection Procedure:
Kansas State University Biological and Agricultural Engineering Department
DropletScan used to analyze droplets:
System ComponentsSystem Components
Kansas State University Biological and Agricultural Engineering Department
Results and Discussion
Kansas State University Biological and Agricultural Engineering Department
Volume Medium Diameter:
549*
625*
571* 582
500
520
540
560
580
600
620
640
Mic
ron
s
TT AI AM ULD
VMD (50%)
*Significant .05
Kansas State University Biological and Agricultural Engineering Department
Control: Tip / Pressure
50
60
70
80
90
100
% C
ontr
ol
Velvetleaf Sunflower Sorghum Corn
Tip - 14 DAT
TT AI AM ULD
*
0
20
40
60
80
100
% C
ontr
ol
Velvetleaf Sunflower Sorghum Corn
Pressure - 14 DAT
30 psi 50 psi 70 psi
*Significant
Kansas State University Biological and Agricultural Engineering Department
Tip and pressure interactions:
50
60
70
80
90
100
% C
ontr
ol
TT AI AM ULD
Tip * Pressure - Velvetleaf - 14 DAT
30 50 70
50
60
70
80
90
100
% C
ontr
ol
TT AI AM ULD
Tip * Pressure - Common Sunflower - 14 DAT
30 50 70
50
60
70
80
90
100
% C
ontr
ol
TT AI AM ULD
Tip * Pressure - Sorghum - 14 DAT
30 50 70
50
60
70
80
90
100
% C
ontr
ol
TT AI AM ULD
Tip * Pressure - Corn - 14 DAT
30 50 70
Kansas State University Biological and Agricultural Engineering Department
% Area coverage - water sensitive paper:
Gramoxone-Tip-Pressure Interaction
0.0
10.0
20.0
30.0
40.0
50.0%
Are
a C
ov
era
ge
Touchdown-Tip-Pressure Interaction
0.0
10.0
20.0
30.0
40.0
50.0
% A
re
a C
ov
era
ge
LSD 11.5%
LSD 11.5%
Kansas State University Biological and Agricultural Engineering Department
Summary of findings Dv0.5 (µm) (VMD):
Venturi tips produced larger droplet VMD’s than the turbo flat-fan.
The AI produced significantly larger droplet VMD’s than the Air Mix and turbo flat-fan, but not the ULD.
Kansas State University Biological and Agricultural Engineering Department
Summary of Findings: %Area Coverage
Significant differences were measured for percent area coverage among chemical, tip, and pressure interactions.
Means for Percent area coverage ranged from 47 to 20 percent with means separated by at least 11.5% considered significant.
Kansas State University Biological and Agricultural Engineering Department
Summary of findings: Efficacy
Very few significant efficacy interactions were measured among herbicide, tip, and pressure variables.
Paraquat provided better velvetleaf control.
Glyphosate gave better sorghum and corn control.
Common sunflower control was simmilar with each product.
Kansas State University Biological and Agricultural Engineering Department
Summary of findings: Efficacy cont. Only minor differences in control were
measured among tips and pressures. The turbo flat-fan tended to be slightly
lower (<10%) in control than the venturi tips.
AI and Airmix tips tended to give lightly better (no significance) control than the ULD.
No significant differences were found in weed control among the three pressures.
Kansas State University Biological and Agricultural Engineering Department
Final thoughts:
Why reduced control with turbo flat-fan?– high temperature, low humidity resulting in
smaller drops (evaporation) that were quicker drying.
Venturi tips performed well regardless of whether a systemic or contact herbicide was used.
Performance over a wide range of pressure is also possible.
Venturi tips appear to be a viable option to minimize spray drift potential while maximizing performance.
Kansas State University Biological and Agricultural Engineering Department
Thanks
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