By: Carlos Tapia, Founder and Technical Director of Avium; Bruno Tapia, Avium Consulting Coordinator; Ricardo Rojas, Avium Technical Advisor.
The VHA aims to recognize the real canopy volume expressed in L/ha to objectify foliar applications to the particular need of each orchard or objective.
It is known in the world of fruit growing that season after season difficulties have arisen mainly associated with the pandemic, but which have brought with them challenges for cherry producers, who have had to face not only logistical problems, but also a shortage of labor and the sustained rise in products directly linked to production; therefore, work has been done to develop new management alternatives to seek to mitigate the negative economic effects of the current situation. In its search, it has been possible to determine a gap for improvement for the fields that can bring many economic benefits to producers and thus achieve the long-awaited success in cherry production in Chile.
The fruit industry should be aware of the great importance of the Tree Row Volume (VHA) or better known in English as Tree Raw Volume (TRV) when it comes to correctly executing the different foliar applications, whether as part of the phytosanitary program or mainly in very technical and delicate applications such as the use of dormancy breakers; the latter not exempt from problems associated with the correct use of this index. Although the determination of the correct wetting volume is based on a simple mathematical calculation and is known to the agricultural sector, but not the decisive role it plays in production, there is no good dissemination to put it into practice and to make known the real impact and benefits that could be brought about by the execution of good applications with their turbofoggers, whether technical or economic.
However, to continue to determine the correct use of the canopy volume, it is necessary to consider and start from a known base, which is the correct calibration of the turbo-nebulizing equipment; without this key milestone of successful field production, one cannot continue forward, since wetting, coverage, working speed and high air flows are closely related to the effectiveness of the applications and to the equipment fulfilling the function together with a trained operator.
The VHA aims to recognize the real volume of the canopy expressed in L/ha to objectify the foliar applications to the particular need of each orchard or objective. The measurements evolve as the phenological states of the cherry tree advance throughout the season, and can have a volume for winter applications, contemplated from 100 % of leaf fall to exposed bouquet or white bud, where the 75% of the VHA is used; then it changes taking the period of full flower during the season and in post-harvest assuming the use of the 100% of the VHA, coinciding with J. Rüegg and O. Viret, who demonstrate through a study of the evolution of canopy volumes throughout the season of different stone fruit species, including the cherry tree, where it is represented in 3 stages, beginning of flowering, 28 days later and beginning of harvest.
The VHA responds to the following formula:
A: Crown width (m) x B: Effective crown height (m) x 936
VHA = —————————————————————————– = L/ha
Distance between rows (m)
A: Cup Width: Calculate an average of the bottom and top width (measured from the first branches) projected in the row.
B: High Cup cash: Calculate the height of the crown from the first fruit branches to the apex of the plant, without considering the base of the trunk.
936: Constant conversion factor to convert to L/ha.
Distance between rows: Measured in meters from the center of each trunk.
You can visit the following link: https://smartcherry.cl/infografias/medicion-vha/
The above, with a couple of exceptions during the application season, where even 150% of VHA is used in winter applications to achieve greater effectiveness against scale, spider mite or phytosanitary control of pests and diseases (example: Calcium Polysulfide, mineral oil, Pyriproxyfen). And on the other hand, just as important or more important is the use of only 75% of VHA for the application of dormancy breakers, since phytotoxicity problems have been recorded when using volumes greater than those recommended, reaching a decrease in production of up to 80% and, consequently, differentiated management of pruning and recovery of trees together with economic losses.
A tool used to determine correct wetting rates so common to apple growers is described very well by Terrenece Robinson in one of her publications under the name “Spary Mixing Instructions Considering Tree Raw Volume – TRV”.
With a sustainable view towards fruit growing and the efficient use of resources in production, the use of this powerful and simple tool becomes more important. It has already been addressed by a group of researchers from the Catholic University of Uruguay, where they managed to determine the reduction of 30-60% in the use of phytosanitary products with no differences in control compared to standard treatments, consistent with what has been observed in some orchards in Chile.
Below is a real example of a winter foliar application for the purpose of weed control. pseudomonas in 2 quarters, formation and production with a volume used by the producer, the real volume needed and its economic impact for the 5 applications of this product in the season:
From the table above it can be seen that the producer was applying a larger volume than necessary by not using the VHA formula correctly, which resulted in a loss of 50% of the application cost in Santina; that is, with the inputs for said application he could have covered 2 hectares, possibly with less work time/ha (machine hours) if the terrain allows it, greater efficiency of the operator's time (JH), rational use of the phytosanitary product and water and better use of the installed capacity in the field, since there is less stock of products in the warehouse. The above is also demonstrated in a trial by the National Institute of Agricultural Technology of Argentina (INTA), where savings greater than 60% were achieved in terms of phytosanitary products in the control of citrus scab.
It has now been shown that there is a technical improvement gap with a major economic impact for producers who have not been able to visualize it, since with typical wettings of 1,500 and 2,000 L/ha, often due to an operational issue adjusted to the volume/ha of the turbo-foggers, they do not take any measurements in the field that can determine the real need for the volume to be applied in each quarter; on these occasions, the operational role is often given greater importance than the technical one, failing to reach a balance between the two at the time of application and, consequently, unvisualized economic losses that could help reduce costs in the phytosanitary item. That is, under a production program with an associated cost of US$4,000/ha, with these small adjustments, US$3,000/ha could be reached, with a reduction of 25%, or even close to 50% in orchards in formation, only by adjusting and using the VHA corresponding to the reality of each producer.
Future vision
Future work should aim to overthrow the bad policy in the field that the more water is applied, the better; in this sense, Avium is working hard to determine the correct VHA for each of the combinations and training systems in cherry trees. In order to objectify this important parameter at the orchard level, artificial intelligence is being used, through the use of RGB images captured in the field by unmanned flying equipment such as Drones.
The result of these flights are high-resolution, georeferenced images, which are processed using artificial intelligence (AI), providing a characterization of each plant within a section that is delimited prior to the flight. This AI and the joint work of platforms specialized in reading RGB images and that are adapted for this fruit species, is capable of determining the VHA for each sector, and they are even capable of generating color maps that indicate the different volumes in a more visual way.
Use of artificial intelligence in cherry orchard.
The appropriate use of this information is key to making correct decisions regarding the use of resources in the field. Each color indicates the canopy volume of each tree; the red color does not always indicate a bad tree, but rather shows that the canopy volume is smaller than the green color. The next step is to compare the image with the characteristics of each plot.
In many cases, lower canopy volumes are associated with sectors with physical and/or chemical soil limitations; with the use of these images, it would be possible to sectorize and use the volume of water needed for that particular condition, which translates in the long run into lower production costs. In addition, it has been seen that lower VHA indices are related to weak plants, which are those that in the future present very high fertility indices and subsequent fruit set. With the use of these images, it has been possible to discriminate this type of plants and/or sectors and recommend differentiated management such as bud thinning (with the objective of improving the leaf/fruit ratio), an extremely costly task, which in many cases is done in large sectors of the field, there being no real need to carry out this task on all plants.
Although there are already quite precise preliminary results for the determination of VHA, further work is needed to adjust both the operation and the adoption of new technological tools in orchards.
Literature
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, Francesescatto. P, Cowgill. W. 2018. “Spary Mixing Instructions Considering Tree Raw Volume – TRV”. CornellUniversity. 3 p.
3. National Institute of Agricultural Technology (INTA). Comparison of two application volumes in plants with and without pruning for the control of citrus scab in Satsuma Okitsu mandarin.
4. Abarca. P. 2020. How to determine the application volume in fruit trees using hydropneumatic sprayers?. Agricultural Research Institute (INIA). Technical sheet No. 48.
5. J. Rüegg and O. Viret. 1999. Determination of tree row volume in stone-fruit orchards as a tool for adapting the spary 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. Hort Act. 525, ISHS 2000.
