There are many different things to consider when spraying pesticides that can impact efficacy including water volume, spray quality, temperature, and pressure. This document can be used as a quick reference for spraying Bayer products. For complete instructions, always refer to the product label.


Table 1. Herbicide modes of action, minimum water volumes with low drift nozzles and maximum spray quality. Note that higher volumes may allow for coarser sprays.1

Herbicide Group (mode of action) Example of Active Ingredients Water Volume (US gpa) Water Volume (L/ha) Spray Quality
1 clodinafop, pinoxaden, clethodim, fenoxaprop 7 – 10 70 – 100 Medium – Coarse
2 thifensulfuron, tribenuron, imazethapyr, imazamox, thiencarbazone-methyl 6 – 10 60 – 100 Coarse – Very coarse
4 2,4-D, MCPA, dicamba, clopyralid, fluroxypyr 7 – 10 60 – 100 Ultra-Coarse
5 atrazine, metribuzin 8 – 10 80 – 100 Medium - Course
6 bromoxynil 7 – 10 70 – 100 Medium – Coarse
9 glyphosate 3 – 5 30 – 50 Coarse
10 glufosinate 10 – 12 100 – 120 Medium – Coarse
14 carfentrazone, saflufenacil 8 – 10 80 – 100 Medium – Coarse
15 metolachlor, pyroxasulfone 10 100 Coarse – Very coarse
22 diquat 10 – 15 100 – 150 Medium – Coarse
27 pyrasulfatole, tembotrione 7 – 10 70 – 100 Medium – Coarse
*For tank mixes, always default to the highest tank mix water volume.

Hard water can affect herbicide performance. Heavy loads of calcium (Ca) and magnesium (Mg) in the farm water source can significantly reduce the performance of glyphosate. Other chemistries affected by hardwater include glufosinate and 2,4-D. If weed control is repeatedly poor, water hardness should be tested.

  • >700ppm Ca and Mg – issues may arise if using rates lower than 0.67L/acre of Roundup WeatherMAX® with Transorb® II Technology or Roundup Transorb® HC Herbicide
  • 500-700ppm Ca and Mg – may experience variable results
  • <500ppm Ca and Mg – this is acceptable

Ammonium Sulfate (AMS) can be used to combat hard water that is heavy in calcium. It doesn’t influence the other hard water elements such as magnesium and iron.

Temperature affects herbicide performance by effecting how plants grow. In general, herbicides tend to work best in warm, mid-low humidity, and sunny conditions when plants are actively growing. Post emergent herbicides work best between 15⁰C and 28⁰C.2

  • Plants growing under cooler conditions are less able to take up the chemical and convert it to other forms. The same can be said for night-time applications.
  • Cooler temperatures: If air temperature is going to dip below 5⁰C a day or two before or after application, crop injury may occur and weed control will be reduced. Watching the forecast for frost or cooler temperatures is important when planning your herbicide application.2

    Group Very Important Important Less Important
    1 X
    2 X
    4 X
    5 X
    6 X
    9 X
    10 X
    27 X

  • In general, avoid applying in severe heat conditions (hot and dry) as the rate of chemical evaporation increases reducing product efficacy. High temperatures increase the potential for significant crop response.

Temperature Inversions: small droplets will remain suspended in a concentrated cloud. Chemistry applications should be stopped during this time due to increased risk of off-target movement and drift.

  • Do not apply during periods of dead-calm. Wind recommendations 5 to 15km/hr (2-10 mph)
A visual tool highlighting the difference between the ideal and not ideal conditions for product application. On this diagram, typical conditions (ideal) highlight the vertical mixing of air, which occurs at 11:00 a.m. (in the example) with winds between 4-8 mph, producing favourable conditions for warm air to cool moving upward. Temperature inversion (not ideal or dead-calm), shows inversion air near the surface, which occurs at 7:15 a.m. (in the example) with winds at less than 1 mph, when cool air remains below warmer air.

Product Ground Application Calibration

When applying pesticides, it is important to select the correct nozzles for the right situation. Inaccurate pesticide application rates, spray patterns and droplet size can lead to the movement of pesticides away from the targeted area and reduce pesticide effectiveness. Minimizing drift is especially important for herbicides. Prior to pesticide application, every sprayer should be thoroughly calibrated before the first use of the season, and the calibration should be checked periodically throughout the season whenever a new nozzle configuration and application pattern is employed.

The following table summarizes guidance on appropriate nozzle types, droplet, and PSI for Bayer products. As a reminder, vigorous, continuous agitation is essential for proper mixing throughout filling and spraying operations of all product tank mixes. Always read and follow label directions.

Table 2. Nozzle and pressure recommendation for ground application of common Bayer Pesticides.

*With all the products listed, PSI should be kept above 30. Spray pattern loss can occur if pressure is less than this.

Product Active Ingredient Droplet
Buctril® M Herbicide bromoxynil(6) , MCPA(4) Coarse
Cirray Herbicide fenoxaprop-p-ethyl(1), pinoxaden(1) Medium
Infinity® Herbicide pyrasulfatole(27), bromoxynil(6) Medium to coarse
Infinity® FX Herbicide pyrasulfatole(27), bromoxynil(6), fluroxypur(4) Medium to coarse
Laudis® Herbicide tembotrione(27) Medium
Pardner® Herbicide bromoxynil(6) Medium to coarse
Puma® Advance Herbicide fenoxaprop-p-ethyl(1) Medium to coarse
Roundup WeatherMAX® with Transorb® II Technology glyphosate(9) Coarse to very coarse
Roundup Xtend® 2 Herbicide with VaporGrip® Technology glyphosate(9), dicamba(4) Extremely coarse to ultra coarse
Sencor® Herbicide metribuzin(5) Medium to coarse
Thumper® Herbicide bromoxynil(6), 2-4,D(4) Coarse
Tundra® Herbicide bromxynil(6), fenoxaprop-p-ethyl(1), pyrasulfatole(27) Medium to coarse
Varro® Herbicide thiencarbazone-methyl(2) Coarse to very coarse
Velocity m3 Herbicide bromxynil(6), thiencarbazone-methyl(2) pyrasulfatole(27) Medium to coarse
Xtendimax® 2 Herbicide with VaporGrip® Technology dicamba(4) Extremely coarse to ultra coarse
Delaro® Fungicide prothioconazole(3), trifloxystrobin(11) Medium
Delaro® Complete Fungicide prothioconazole(3), trifloxystrobin(11), fluopyram(7) Medium
Proline® Fungicide prothioconzaole(3) Medium
Proline® GOLD Fungicide prothioconazole(3), fluopyram(7) Medium
Prosaro® XTR Fungicide prothioconzaole(3), tebuconazole(3) Medium
Prosaro® PRO Fungicide prothioconazole(3), tebuconazole(3), fluopyram(7) Medium
Stratego® Fungicide prothioconazole(3), trifloxystrobin(11) Medium
TilMOR Fungicide prothioconazole(3), tebuconazole(3) Medium
Decis® Insecticide deltamethrin(3) Medium