The document discusses the critical impact of water quality on herbicide efficacy, emphasizing that factors like pH, hardness, alkalinity, and turbidity significantly influence herbicide behavior in spray solutions. It highlights that clean water is essential, especially for herbicides with high Koc values like glyphosate, which can be adversely affected by poor water quality and turbidity. Guidelines for proper tank mixing and the role of additives like Manta Ray buffer are also provided to improve outcomes.

1. 2023 How water quality effects
herbicide results

2. ● Water is the used as the main carrier When you
make herbicide applications water is the main
carrier that you use.
● Spray solutions commonly contain 95% or more
water
● How a herbicide behaves in a tank mix is a result of
the water and herbicide chemistry

3. Factors that can effect how well a herbicide will work
include:
● Water pH
● Hardness
● Alkalinity
● and turbidity.
Water pH is the concentration of H+ ions.
The amount of calcium, magnesium, sodium and iron
will give you water hardness.

5. ● Hardness is expressed as an equivalent of calcium
carbonate.
● Turbidity is caused by suspended solids, soils, or
organic matter
● Alkalinity refers to carbonate and bicarbonate levels
in water
● An irrigation suitability analysis should have this
information

6. Below are the common ions found in water but other
ions can also have an effect
Cations (+ charge). Anions -
charge
■ Calcium. Sulphate
■ Magnesium. Chloride
■ Sodium.
Bicarbonate
Carbonate

7. ● Dirty spray water can deactivate herbicides with
high Koc values
● Clean water is very important for these herbicides
● Herbicides with low Koc values are not affected

8. Sulfonylurea herbicides

9. The solubility of sulfonylurea herbicides (Destiny,
Duke, Tribute, Monument increases with higher pH
● The amount of dissociation depends on the pH of
the water
● Dissociated herbicide molecules have a negative
charge
● Herbicides with high Koc values are sensitive to
turbid water

10. Glyphosate

11. ● Glyphosate has a high Koc and is greatly affected
by turbidity. Effects can be reduced by
● Using higher rates
● Adding sulphate of ammonia to the spray solution
or adding a spray buffer like Manta Ray
● Using the spray immediately after mixing
● Using low volume sprays.

13. ● Common to get poor results
● Poor Water quality often the reason
● Hardness higher than 350 mg/L can affect low rates
and over 700mg/L can affect high rates

14. Tank mixing sequence for spray
buffer

15. 1 2 3
Half fill spray
tank with water
and commence
agitation
4
Add the appropriate amount of
Manta Ray Buffer.
5
Add the appropriate
amount of herbicide,
fungicide or foliar fertilizer
Continue agitation
Top up with water