By: Carlos Tapia, Founder and Technical Director of Avium; Bruno Tapia, Avium Consultancy Coordinator; Ricardo Rojas, Avium Technical Consultant.
The objective of the TRV is to recognize the real crown volume expressed in L/ha in order to objectify the individual need of foliar applications at each orchard or objective.
It is well-known in the fruit growing world that season after season new difficulties have arisen primarily associated with the pandemic, but they have brought challenges with them for cherry growers, who have had to face not only logistic problems, but also a workforce shortage and sustained increase of products directly linked to production; therefore, new management alternatives have been developed to seek to mitigate negative economic effects of the present situation. In this search, we have been achieving the determination of an improvement aperture for the fields that may bring many economic benefits for growers and in this way reach the so longed-for success of cherry production in Chile.
The fruit growing industry must be aware of the great importance of the Tree Row Volume (TRV) or known in Spanish as Volumen de Hilera de Árbol (VHA) at the time of executing, in the best way, the different foliar applications, may it be the phytosanitary program or primarily in very technical and delicate applications as is the use of dormancy breakers; the latter are not exent of problems associated to the correct use of this index. Despite the determination of the correct wetting volume in function of a simple mathematic calculation that is known by the agricultural sector, this is not so in the decisive role that it takes on in production, there is not good communication of this in order to put it into practice and to make the real impact and benefits known (whether technical or economical) that could give rise to the execution of good applications with its turbo-mist sprayers.
However, to move ahead in the determination of the correct use of crown volume, we must consider and start from a known base, which is the correct calibration of turbo-mist sprayer equipment; without this key milestone of successful field production, we cannot move forward, since the wetting, covering, work speed and elevated air flow are closely related to the efficacy of the applications and with which the equipment complies along with a trained operator.
The objective of the TRV is to recognize the real crown volume expressed in L/ha to objectify the foliar applications to the individual need of each orchard or objective. The measurements evolve as the phenologic stages of the cherry tree advance throughout the season, being able to have a volume for the winter applications, contemplated from 100% leaf fall to the exposed cluster or the white buds, where 75% of the TRV is used; then it changes taking the period of full bloom during the season and post-harvest assuming the use of 100% of the TRV, coinciding with J. Rüegg and O. Viret, who show in a study the evolution of tree crown volumes in the season of the different stone species, among them the cherry tree, where they are represented in 3 stages, beginning of flowering, 28 days afterwards and the beginning of the harvest.
The TRV, responds to the following formula:
A: Crown width (m) x B: Effective crown height (m) x 936
TRV = ————————————————————————– = L/ha
Distance between rows (m)
A: Crown width: Calculate an average of the lower and upper width (measured from the first branches) projected in the row.
B: Effective crown height: Calculate the height of the crown from the first branches of the fruit tree to the apex of the plant, without considering the base of the trunk.
936: Constant conversion factor to express in L/ha.
Distance between rows: Measured in meters from the center of each trunk.
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In the above, with a few exceptions during the application season, where even 150% of TRV is used in winter application to achieve ideal effectiveness for the control of scales, spider mites or phytosanitary pests and diseases (example: Calcium Polysulfide, mineral oil, Piriproxyfen). On the other hand, the use of only 75% of the TRV is as or more important than the application of dormancy breakers, since phytotoxicity problems have been registered when using volumes higher than recommended, even decreasing production up to 80% and, consequently, using differentiated management of pruning and tree recovery together with the economical losses.
A tool used to determine the correct wetting which is so common for apple growers, is described very well by Terence Robinson in one of his publications under the name of “Spary Mixing Instructions Considering Tree Row Volume – TRV”.
With a sustainable outlook of fruit growing and the efficient use of production resources, the use of this powerful and simple tool becomes more important, that it has been looked at by a group of investigators from the Catholic University of Uruguay, where they were able to determine the reduction between 30-60% of the use of phytosanitary products without control differences faced with standard treatments, concordant with what has been observed in some orchards in Chile.
In the following, a real example of a winter foliar application is indicated with the objective of controlling pseudomonas in 2 plots, formation and production with a volume used by the grower, the real volume necessary and its economic impact for the 5 applications of this product in the season:
From the preceding table we can deduce that the producer was applying a volume that was higher than necessary when not using the TRV formula correctly, which translated to a 50% loss of the application cost in Santina; that is, with the supplies of that application they could have covered 2 hectares, possibly with less workforce time/ha (machine hours) if the land had allowed it, higher efficiency of the operator time (JH), rational use of the phytosanitary product and the water and better use of the capacity found in the field, since there is less stock of products in the warehouse. The above is also shown in a trial by the Instituto Nacional de Tecnología Agropecuaria de Argentina (INTA – National Institute of Agricultural Technology), where they achieved savings of more than 60% in the concept of phytosanitary products in the control of citrus scab.
Currently, it has been possible to show that there is a technical improvement breach with great economic impact for producers that they have not been able to visualize, since the typical wettings of 1,500 and 2,000 L/ha, many times because of an operational adjustment to volume/ha of the turbo mist sprayers, they don’t make any measurement on site that may determine the real volume need to apply to each plot; on these occasions, they give the operative role greater importance than the technical one, not being able to reach a balance between both at the time of application and, therefore, there are economical losses not visualized that could have helped to reduce costs in the phytosanitary item. That is, under the production program with a cost associated to the USD$ 4,000/ha, with these small adjustments, it could have been USD$ 3,000/ha, because of a 25% reduction, or even near 50% in orchards in formation, only adjusting and using the TRV corresponding to the reality of each grower.
Future vision.
Future work should be aimed at eliminating bad policies in the field that while there is more water volume the thought is that “it’s much better”; in this sense, Avium is working hard to determine the right TRV for each of the combinations and conduction systems for cherry trees. As a way to objectify this important parameter at the orchard level, artificial intelligence is being used, through RGB images taken in the fields by unmanned flight equipment as Drones.
The result of these flights is high-resolution images that are geo-referenced; they are processed through artificial intelligence (AI) giving a characterization of each plant inside the plot that is defined prior to the flight. This AI and the conjoint work of specialized platforms in the reading of RGM images and that are adapted to each fruit tree species, is capable of defining the TRV for each sector – they are even capable of generating color maps that indicate different volumes in a more visual way.
Use of artificial intelligence in cherry orchards.
Preliminary results of calculation of crown volume (TRV) through unmanned air vehicles (UAV).
The proper use of this information is key to making correct decisions such as the use of resources in the field. Each color indicates the crown volume of each tree; the color red doesn’t always indicate a bad tree, but shows that it is a crown volume that is lower with regards to the color green. The next step is to make the image speak with the characteristics of each plot.
In many cases, lower crown volumes are associated to sectors with physical limitations and/or soil chemicals; with the use of these images you could split them and occupy water volume that is needed for this condition in particular, which translates in the long run to lower production costs. Furthermore, we have seen that lower indexes of TRV are related to weak plants, which are those that in the future will present very high indexes of fertility and later setting. With the use of these images, we have been able to differentiate this type of plant and/or sector and recommend differentiated management, like for example the thinning of buds (with the objective of improving the leaf/fruit relationship), a very costly job, that in many cases is done in large sectors of the field, not needing to really carry out this work on all the plants.
Even though there are very precise preliminary results for the determination of TRV, we must keep working to adjust the operative as well as the adoption of new technological tools in orchards.
Bibliography
1. R. Deleón, G. Vicente, R. Zoppolo, A. Arnaud and M. Miguez, «LIDAR Based, Tree Row Volume Estimation for Phytosanitary Products Reduction in Fruit Trees Orchards,» 2020 IEEE International Symposium on Circuits and Systems (ISCAS), 2020, pp. 1-4, doi: 10.1109/ISCAS45731.2020.9181291.
2. Robinson. T, Francsescatto. P, Cowgill. W. 2018. “Spray Mixing Instructions Considering Tree Row Volume – TRV”. Cornell University. 3 p.
3. Instituto Nacional de Tecnología Agropecuaria (INTA). Comparación de dos volúmenes de aplicación en plantas con y sin poda para control de sarna de los cítricos en mandarina Satsuma Okitsu. (Comparison of Two Application Volumes in Plants with and without Pruning for Citrus Scab in Satsuma Okitsu Mandarines)
4. Abarca. P. 2020. ¿Cómo determinar el volumen de aplicación en frutales utilizando pulverizadores hidroneumáticos? (How to Determine Application Volume in Fruit Trees using Hydro Pneumatic Spray Equipment?). Instituto de Investigaciones Agropecuarias (INIA). Ficha técnica n° 48.
5. J. Rüegg and O. Viret. 1999. Determination of tree row volume in stone-fruit orchards as a tool for adapting the spray dosage. Bulletin OEPP/EPPO Bulletin 29, 95-101.
6. Steffek. R, Reisenzein. H, Persen. Tree row volume a new way for the registration of plant protective agents in orchards? Results of 3-year field trials in Austrian Apple orchards. Acta Hort. 525, ISHS 2000.
