Foliar Treatment: Details that make a difference

Foliar Treatment: Details that make a difference

By: Eduardo Parra – Agronomy Engineer, Greenmark Technical Manager.

When a foliar treatment with an agrochemical doesn’t produce the expected results it is common to think that maybe the correct dose was not applied or that the product used didn’t work. It is less frequent to reflect upon the nozzle used, volume utilized, speed of the application or water quality.

Water quality

The water used is not only the means that allows for the distribution of the agrochemical, but depending upon its composition it may greatly modify the effectiveness of the treatment.


Most agrochemicals need acid pH (< 7) to avoid the alkaline degradation of their active ingredients, therefore, it is essential to lower the pH of the water when its value is larger than 5.5 – 6, considering as well, that some products are alkalizing (they increase the pH).

The speed with which alkaline hydrolysis is produced depends primarily upon the chemical properties specific to the agrochemical, the pH in the water mix and the period of time that the product is in contact with it. Values higher than pH 8 and 9 may cause an extremely fast alkaline hydrolysis to the point that the degree of phytosanitary control may be lost to great degree. The degradation of an agrochemical is generally expressed in terms of its half-life that is the period of time that it takes to decompose in water at half of its original concentration (50% of hydrolysis): half-life DT50.


Murky water contains suspended soil and clay particles that can reduce the effectiveness of agrochemicals sequestering their active ingredients.

There are a great number of dissolved substances in water, mostly salts. Among the main ions present, those that have the most influence in the behavior of agrochemicals are Ca++ and Mg++ expressed as a carbonate equivalent of calcium that is reflected in the hardness of the water.

Hard waters produce sediment that may obstruct nozzles and filters of the spray equipment.

Elevated content of dissolved ions form insoluble salts with agrochemicals or the surfactants that stabilize them and make it difficult for the phytosanitary and nutritional products to dissolve.

In order to guarantee the effectiveness of the foliar sprays it is recommended to achieve pH of the solutions of:

  • 5.5 – 6.0: to apply agrochemicals and fertilizers 
  • 4.0: to apply herbicides and synthesis hormones 
  • 4.0: to clean tissues from fumagina / honeydew 

Water Treatment 

Most times it is necessary to acidify the water in order to achieve those pH levels. Thus it is possible to:

– protect the phytosanitary properties from alkaline hydrolysis

– increase the solubility and compatibility among the solution products

– reduce the obstructions in the spray machinery

The quantity of acidifying product necessary to reach said pH is different for each kind of water because it depends upon the substances present in it which determine its pH, hardness, electric conductivity, etc.

To improve the quality of the water used in sprays and the characteristics of the solutions as well as its penetration, the company GREENMARK has developed VYRER PLUS, an acidifying fertilizer which colors the water differently depending upon the pH, allowing it, therefore, to safely reach the desired pH without the need of equipment. 

VYRER PLUS is distributed by GREENMARK and is used in fruit trees, vegetables, crops, etc. throughout the cycle of the plant.

Recommendation for the preparation of solutions

  • filter clay and organic material (the water must be transparent).
  • fill ¾ of the machine’s tank with water.
  • correct pH with VYRER PLUS.
  • make a premix of the products separately with the solid formula (with acidified water) and add to the tank.
  • pour in the liquid formulations.

Keep continuously shaken and before adding a new product wait for the complete homogenization of the prior one.


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