Water Volume, Tractor Speed, and Nozzle Type Effects on Spray Coverage Eric P. Prostko, Extension Weed Specialist Paul E. Sumner, Extension Ag-Engineer Paul E. Sumner, Extension Ag-Engineer The University of Georgia Peanut Achievement Club

Factors That Influence Postemergence Herbicide Performance  weed size  rate  environment –moisture –temperature –humidity  application –water volume (GPA) –tractor speed –nozzle type

Current Application Trends  low water volumes –10 GPA or less  faster tractor speeds  nozzle types –Air Induction (AI) –Turbo-Jet (TJ) –Hollow-Cone (HC)  Why?? –RR crops –More acres –Labor issues

U.S. Acres Planted to Herbicide Resistant Varieties Source: NASS Includes stacked

3.5, 5.0, 7.0 MPH 10, 15, 20 GPA XR-Flat Fan (XR-FF) and Hollow Cone (HC) Nozzles 9 replications Kromekote water sensitive cards

Examples of the nozzles used in these tests. Flat Fan Hollow Cone (Whirl-Jet)

RESULTS

Nozzle Type and GPA Effects - I 3.5 MPH Tractor Speed LSD 0.10 = 3

Nozzle Type and GPA Effects - II 5.0 MPH Tractor Speed LSD 0.10 = 3

Nozzle Type and GPA Effects - III 7.0 MPH Tractor Speed LSD 0.10 = 3

10 GPA - 7 MPH – HC (12% coverage) 20 GPA – 3.5 MPH – XR (FF) (45% coverage)

Summary  3-way interaction between tractor speed, GPA, and nozzle type  HC nozzles provided less coverage than XR-FF nozzles  Tractor speed –FF and 20 GPA = 3.5 mph > 5.0 mph = 7.0 mph –HC and 10 GPA = 3.5 mph > 5.0 mph = 7.0 mph –HC and 15 GPA = 3.5 mph > 7.0 mph  increases in GPA improved coverage –20 GPA > 15 GPA > 10 GPA  best coverage (45%) –3.5 MPH/20 GPA/XR-FF  least coverage (12%) –7.0 MPH/10 GPA/HC

Why is this important?  Application techniques for glyphosate (systemic) are not adequate for other types of herbicides such as paraquat (contact)!

Peanut Herbicides (POST) HerbicideActivity 2,4-DBsystemic Basagrancontact Cadresystemic Classicsystemic Cobracontact Gramoxonecontact Poastsystemic Pursuitsystemic Selectsystemic Stormcontact Ultra Blazer contact