By: Raúl Osorio – Director of Peulla Consulting and Services
«The great desire of every producer is undoubtedly to advance their harvest and improve the productive potential of their orchard and that this translates into a better profitability of their business. Dormancy breakers (RD) continue and will continue to be a subject of study for researchers and extensionists, who are constantly trying to replicate in cherry orchards different strategies that can advance or homogenize the initial phenological states (flowering and budding), and translate them into the advancement or homogenization of the harvest. However, it is necessary to be clear when and when to use hydrogenated cyanamide or a dormancy breaker.«. (https://cutt.ly/imHSnWH)
For the advisors and researchers cited in the same publication it is very important:
- Correct application of the products must be considered, as well as the calibration of the machinery used to carry out these applications. A clear example of an error is to carry out an application outside the dosage, with a high concentration or excessive wetting, which can cause phytotoxicity or damage to the wood and flower primordia. It is important to bear in mind that dormancy breakers are not used in doses per ha, but in concentration or percentage: for example 2 liters in 100 liters of water (2 %), 3 liters in 100 liters of water (3%), etc.
- Regarding the machines, it is estimated that 90% of the machines used in Chile to apply agricultural products have some calibration problem, a situation that must be resolved urgently because the effectiveness of the products, in this case Hydrogenated Cyanamide, or Dormancy Breakers (RD), depends 50% on their application, along with their correct dosage.
- A calibrated machine, with adequate pressure and speed, nozzles in good condition, etc. allows the application of any product to be increased. It should not be forgotten that these products (Cyanamide and RD) act by contact, therefore, they require water as a carrier, and a well-calibrated machine will reach all parts of the tree with the products in a homogeneous and correct manner, especially the highest part (https://cutt.ly/imHSnWH).
We have already reviewed in the publication the important factors to consider for winter applications, it is vital that:
- Preventive maintenance is carried out on each of the available equipment (atomizers and tractors).
- Have precise calibration guidelines appropriate to each orchard situation according to topography, orchard age and conduction system.
To develop a proper calibration to run these applications we must consider:
- Volume of water to be used
- Canopy volume to be treated (wood shoots and buds)
- Volume of air required to move the applications
- Speed of advance of applications in the field to achieve good coverage or amount of deposit on the target (darts and buds in wood).
Volume of water: We must always consider that our objective is to achieve good “drop coverage” on the organs of our crop (darts and buds) which in turn will depend on: “the height, size or volume of the canopy” or “volume of structures”.
One way to calculate the volume of water to be used is by determining the crop volume through TRV (Tree Row Volume) or Tree Volume. TRV (m3 of tree/ha) = [height of tree from first branches (m) x average width of tree (m) x 10,000 (m2/ha)] / Distance between rows (m).
The size of the trees at this stage of the crop (rest) is very similar in most cherry orchards and will vary depending on the training systems.
Just as an example, we will consider a garden with the following measurements:
-Average tree height from first branch: 2.7 meters (3.2 meters total)
-Average tree width: 2.5 meters
-Planting distance: 4.3 meters
-The TRV = (2.7 x 2.5 x 10,000) / 4.3
-The result will be TRV = 15,697.7 m3 of objective.
To obtain the volume of water to use Byers et.al They represent a volume of 0.0936 L/m3 canopy with foliage.
For our example, therefore, we would need 15,697.7 x 0.0936 = 1469.3 L of water / ha.
However, and according to the publication of the advisors cited in this article (https://cutt.ly/imHSnWH); we only need 70 % of this calculated volume for applications aimed at darts or buds in wood; this calculation is also cited by the Agricultural Engineer Guillermo Lorca Beltran Professor of Agricultural Mechanization at the Faculty of Agronomy and Forestry Engineering, PUC of Chile [email protected], In his article ACCURACY WITHOUT HASTE in the magazine Mundo Agro, a leaf density adjustment index should be applied.
If we apply the factor 0,7 (extremely open), it throws us a volume of water to apply of 1028,5 L of water/ha.
After several years of experience and field applications, and checking the deposits with hydro-sensitive paper, fluorescent paints and also kaolinites for agricultural use, seeking that the drop deposit (covering) does NOT generate excesses or drips, we can apply the factor of 0.75 to this calculation.
Therefore, and for the example and based on field experience, the adjustment recommendation for applications intended for buds and darts in wood:
1028.5 L x 0.75 = 720 L of water/ha.
Field verification with kaolinite.
Volume of air to be displaced in winter applications: Another very important factor to consider is the volume of air needed to move our application toward the target.
One way to calculate the air volume needed is also to determine the crop volume through TRV (Tree Row Volume) or Tree Canopy Volume. TRV (m3 of foliage/ha) = [tree height (m) x tree width (m) x 10,000 (m2/ha)] / Distance between rows (m).
For the same example above, an orchard with an average height of 3.2 meters, with a “branch” width of 2.5 meters and a planting distance of 4.3 meters.
The TRV = (3.2 x 2.5 x 10,000) / 4.3. The result will be TRV = 18,605 m3 x 0.7 = 13.0.23 of target (wood).
This calculated volume is what we must move to reach our objective “Wood”.
The hydropneumatic equipment with air assistance, which is the most commonly used in our fruit growing industry, has different air displacement capacities depending on its model and type of air group.
The different models existing in the country generate quantities ranging from 25,000 to 90,000 m3 of air/hour. To adjust the amount of air/ha (13.023 m3 in the example) we must consider:
- The speed of progress of the application
- Adjustment of the air group multiplier box
- Adjusting the blades to the required position or inclination.
- Adjusting the working RPM.
For our example we will consider the following table of forward speeds in an orchard with a distance of 4.3 meters between rows:
| D. Plantation | km/hour | Time/ha (min) | m3/ha |
| 4,3 | 6 | 23,26 | 14534,9 |
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| D. Plantation | km/hour | Time/ha (min) | m3/ha |
| 4,3 | 6,5 | 21,47 | 13416,8 |
To achieve a better level of deposits, it is always recommended to use the lowest possible speed, considering the operational capacity of the atomizing equipment in the field. (https://www.redalyc.org/pdf/932/93215307.pdf)
Choice of Nozzles: These components must always be kept clean and the flow rate they deliver per minute must be checked and verified to be as indicated by the manufacturer, not exceeding 10 % of wear.
For example:
| Nozzle model | Pressure (bar) | Flow rate (L/min) | Time/ha | No. Nozzles | Final flow rate / ha |
| ATI Blue Empty Cone | 12 | 2,4 | 21,47 | 14 | 721,4 |
| ATF Blue Full Cone | 12 | 2,4 | 21,47 | 14 | 721,4 |
| TVI Blue Anti-drift Vacuum Cone | 12 | 2,4 | 21,47 | 14 | 721,4 |
In order to develop effective and efficient application management plans, we must have previously diagnosed equipment in all its components, repaired and replaced its critical elements, perform annual and periodic maintenance, permanent cleaning and have highly trained personnel to develop the applications that will translate into the success of our crop at harvest with the least impact on the environment and people.
