What Is Foliar Spray Technique?

There are a lot of options out there for controlling the growth of unwanted plants and trees. The foliar spray technique is one of the most widely used methods for controlling plant and weed growth and it is equally important to know how to perform it correctly. Let’s take a look at everything you need to know about the foliar spray technique.

The foliar spray method involves spraying a herbicide over the foliage of a tree or shrub to kill it. The herbicide is absorbed by the leaves and transported throughout the plant disturbing its nutrient flow. This method is ideal for small trees, bushes, and vines smaller than 8 ft in height and for large-scale population control.

What Is Foliar Spray Technique?

The foliar spray method involves spraying herbicides diluted with water at the desired rate over the foliage of the trees or bushes till the point of runoff. The chemical is then absorbed by the leaves and transported throughout the tree.

This method is ideal for use on shrubs, small plants, grasses, and dense vines. Ideally, the targeted plants should not be taller than 8ft. Larger trees will not only be much more difficult to access but the effectiveness of the technique will also reduce.

There are different ways of performing the foliar spray method depending on the type of plants you are dealing with. Sprayers mounted on a vehicle are perfect for targeting plants smaller than 3ft in height over a large area. For personal use, a backpack sprayer is more than enough.

How Are Nutrients and Additives Absorbed by The Plants?

Plants’ foliage tends to absorb nutrients and additives majorly through leaves. Either through the stomata, also known as the main avenue, or through the waxy cuticle layer. As some trees can have a cuticle layer, it is recommended to cover both sides of the leaves with herbicide for optimal absorption in all scenarios.

The stomata of the leaves (the main absorption area for the herbicide if there is no cuticle layer present) opens when the first light of the day touches the leaves and close during the evening. This makes it ideal for you to spray the chemicals either during the morning.

What Is the Best Time Of a Year for Using the Foliar Spray Method?

When it comes to the foliar spray technique, the chemicals or pesticides are absorbed by the leaves. Because of that, the ideal time for spraying would be when the foliage is in full bloom. Thus the technique should be carried out between late spring and early autumn.

You will have much more flexibility when dealing with evergreen trees but it is still recommended to do it before winter.

Tips for Performing Foliar Spray Method.

Although performing the foliar spray technique is quite easy, following some of these tips can greatly impact the overall results.

  1. It is always recommended to use purified water, or at least water that contains a minimal amount of minerals and chlorine. This will help avoid any clogging in the nozzle of the sprayer over repeated use.
  2. Although you can use any backpack sprayer, it is recommended to use solo directional pressurized sprayers. The solo directional sprayer will create a cloud of mist from the solution while spraying. This in turn will minimize the amount of herbicide needed and give the best coverage over the leaves.
  3. Full coverage is absolutely essential, make sure to cover both sides of the leaves.
  4. It is recommended to spray either during the beginning of the day. The stomata in the leaves is open during this time which increases absorption. The stomata in the leaves are open when the temperature is below 80F and when there is high humidity between 55-70%.
  5. Do not spray the solution when the leaves are already wet due to rain, frost, dew or hail. This will deter absorption by the leaves.
  6. Test out the solution on one plant if possible and wait a couple of days to see the results. Although this is not necessary, it can save you a lot of time, effort, and money.
  7. It is recommended to use a wetting agent or surfactant which will help the chemicals stick better to the leaves. You can use Coco wet. Dutchmaster, GO Bioweed, Alg-A-Mic, etc. In some cases, surfactants increase absorption by over 300%.
  8. Spray the plant or tree 2-3 times a week and make sure the chemicals are fully absorbed each time. Repeated use will increase the efficiency and lead to a faster death.
  9. Make sure there is no wind during the time of spray as the herbicides can get carried and possibly affect surrounding vegetation and animals.
  10. Mix some form of a die in the herbicide solution to be able to recognize which plants have already been treated.

What Equipment Do You Need for Performing Foliar Spray?

There are a lot of options for sprayers in the market catering to different budgets and uses. For personal use, it is recommended to go use a backpack sprayer. You should use an adjustable nozzle that can deliver the solution both as a fine mist and coarse particles to reach higher parts of the canopy.

Other than the sprayer, you will only need the herbicide solution for this technique.

What Solutions or Herbicides Should You Use for Foliar Spray Technique?

It is recommended to use herbicides that contain 1-2% solutions of glyphosate, 1-2% solution of Arsenal AC, and 2% solution of Arsenal. Grazon P+D is also highly effective with this technique. But depending on where you live, you might have to get a special license to be able to use Grazon P+D. You can also seek advice from your nearest arborist or hardware store for alternatives.

Read more about Grazon.

IngredientsConcentration in the spray solutionTank Size (3gal)
Grazon P+D1%4 oz
Surfactant¼%1 oz
Dye¼-1/2%1 oz

What Are the Other Uses of the Foliar Spray Technique?

The foliar spray technique is also largely used for spraying beneficial pesticides, nutrients, and herbicides to boost the growth and health of plants and trees. One of the major benefits of using this technique is its ease of use and low cost. This makes it ideal for large-scale applications.


The foliar spray technique is used for controlling the growth of smaller trees, bushes, and vines. It involves spraying a herbicide on the foliage of the tree which is then absorbed by the leaves and transported throughout the tree.
Besides using a foliar spray technique for plant growth control, the foliar spray technique can be also used to boost the growth and health of plants and trees by using different mixtures instead of tree-killing herbicides.

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