To Mix or Not to Mix: That is the Question?

(Tank-mixing Herbicides and Fungicides)

Eric P. Prostko

Extension Weed Specialist

Department of Crop & Soil Sciences

University of Georgia

Why tank-mix agrochemicals?

• Advantages– Increase spectrum of control– decrease time and labor cost– less vine damage– decrease soil compaction

• Disadvantages– Reduced control– Increased crop injury– Physical incompatibility– different spray volumes/nozzle types– adjuvant recommendations

Spray Volumes and Nozzle Tips

• What is the best water volume to use for ……..– fungicides– herbicides

• What is the best nozzle to use for….– fungicides– herbicides

Nozzle Tips

Nozzle Tip

Herbicides Fungicides

Contact Systemic Contact Systemic

AI G E G E

Turbo Teejet

VG VG VG VG

XR

Flat Fan

E G E G

Turbo

Floodjet

NR VG NR VG

Whirl rain cone

VG VG E E

Hollow cone

NR G VG VG

What happens when you mix chemicals?

• additive

* 1 + 1 = 2

• synergistic

* 1 + 1 = 3

• antagonistic

* 1 + 1 = 1 or less

Antagonism

Gramoxone Max 8 ozs/A

Gramoxone Max10 ozs/A

+ Storm (1.5 pt/A)1 DAT

What do the labels tell us?

• In most cases, not very much

• Unclear, vague, and confusing

• Trial and error• Has someone else

done it?

Cadre Tank-Mixes

Headline

MONCUT 70DFECHO® 720 AG

PropiMax* EC

Nichino America ARTISAN

What have we learned?

• Generally no major problems but…..

• Impossible to test under all environmental scenarios

• There are some specific problems

Annual Grasses and Select(Jordan et al. 2003. Peanut Science 30:1-7)

• More of a problem when applied in 25 GPA than if applied in 10 GPA

• % of comparisons where control was reduced– Kocide, ManKocide, Tenn-Cop = 80%

• 7-75% reductions in control– Bravo and others = 69%

• 2-60% reductions in control– Abound = 60%

• 5-13% reductions in control– Folicur and Tilt did not reduce efficacy

Texas panicum control with Cadre/fungicide tank-mixes, 2002 (67 DAT) .

83 82 78 77 7367

75

0

20

40

60

80

100

None BravoWS

Tilt +BravoWS

Headline Abound Folicur Moncut

Fungicide

Con

trol

(%

)

LSD 0.05 = 20LSD 0.10 = 17

A New Publication(For more specifics) • Tank Mixing Chemicals

Applied to Peanut Crops: Are the chemicals compatible?

• June 2004

• Regional publication housed at NCSU (AGW-653)

• Available on-line at: http://www.peanut.ncsu.edu/ag653.pdf

New POST Labels for 2005

• Strongarm– 24c label in GA– No fungicide

tank-mix information

• Cobra

– Label says do not tank-mix

Before spraying…..

• Read label• Water volume

compatible for both• Nozzle type• Contact county agent• Check for physical

compatibility– Jar test

Mixing Order

• some water (1/2) + agitation• water soluble packets• wettable powder in slurry• DF or WDG• liquid flowables• EC• NIS/COC/AMS/UAN• Remaining water

(AMS then glyphosate)

Two-Jar Test

• 1 pt of carrier (water) to each of 2 qt jars• ¼ teaspoon of compatibility agent to 1 jar

– Blendex (Helena)– Mix (Drexel)– Unite (Loveland)

• To each jar, add required amount of pesticide in order suggested previously. Shake well after each addition.

• After all have been added, shake for 15 seconds and let stand for 30 minutes

Other issues

• Adjuvants– How is fungicide

formulated?– How bad are the

weeds?• What about …..

– insecticides– fertilizer– 3 or 4 way mixes

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