Our strategies for agrochemical use will always depend on three factors that are closely related, and the responsibility expressed in proportion to each of these is described in the attached figure 1:
1. Choosing a good agrochemical product (in terms of its active ingredient and effective formula), with sufficient support, reasonable costs given its objective, ideally low environmental impact, and consideration toward its dosage range.
2. Duly using agrochemical products depending on the development states of our crops, plague and disease susceptibility states.
3. Finally, using application equipment that is always well maintained and in good shape, clean and optimally calibrated for the development of applications in a wide range of water volumes or “application rates.”
Figure 1. Factors of responsibility in the effective control of an application.
Each year, specialists in the productive management of fruit crops develop high performance and efficacy programs for agrochemicals, which always focus on efficiency in their usage (fungicides, insecticides, herbicides, growth regulators, bio-stimulants, nutrients and others.) To this effect, they gather updates in tags and usage recommendations; they also corroborate MRL restrictions regarding the different active ingredients for all the markets in which they will be used.
Additionally, a good amount of time is allotted for the verification and updating of new additional restrictions for certain clients in countries that present greater demands or secondary standards (supermarkets). In these cases, we can find the requirements or restrictions for number of active ingredients as part of an individual analysis, individual relative percentages for detected active ingredient concentrations or the sum of these MRLs, as well as other toxicological components such as ARfD, also as an individual relative percentage or as a sum of all parts found.
Another permanent concern is the search for compatibility in agrochemical products used to achieve tank mixing that is chemically and physically compatible; thus being able to limit the use of machinery aimed at this task while achieving several goals with a smaller number of applications (therefore saving on energy and specialized workforce.)
It is also very important for applications in periods of greater susceptibility not to generate stains or deposits on fruits, which provoke “cosmetic” defects. This may cause serious quality damage in the fruit, leading to important losses.
If we consider that the cost of foliar programs (nutrition and health) adds between USD$ 3,000 and USD$ 4,000 per hectare, and that the associated cost of each application is USD$ 25 per hectare (organic material – machinery), while we perform 20 to 25 applications per season; the cost adds up to an extra USD$ 600 per hectare.
In total we are using USD$ 3,600 to USD$ 4,600 per hectare per season; this is undoubtedly a large annual investment which must be used efficiently (https://www.smartcherry.cl/manejos-agronomicos/invitacion-al-uso-efectivo-y-eficiente-de-nuestra-inversion-programas-de-aplicaciones-de-agroquimicos-en-cerezos).
To the search for efficiency in the use of resources we must add the ever-growing concern regarding the use of water volume recommendations adjusted to crop size, development state and objective.
All of the above must be implemented onsite with equipment that is in good shape and periodically maintained, annually calibrated, permanently checked onsite and operated by highly qualified personnel.
A real-life experience of challenges and fulfillment of this task is the following:
Approximately 12 years ago, when the demands for secondary standards began, we realized that they could not be challenged, they would only grow increasingly strict; so we generated new application programs to fulfill demands according to what was shown, on paper, to be the best programs to ensure plague and disease control – in trying to meet these new demands, we were unable to fulfill this goal and in some cases we only did so partly. That is when we realized that at the end of the day the ones who are truly generating this change are our operators and their direct supervisors.
The seasoned Chilean operator has something peculiar: with any tractor, with any turbo nebulizer and in any field disposition; if given an instruction, that operator will get it done without any further information. For example, if the operator is told to apply 1,500 liters per hectare, he will return by the day’s end with the task performed and a final result of 1,500 liters per hectare. The issue lies in how the distribution was made in this orchard. The operator may have started applying the equivalent to 2,500 liters per hectare, then saw that he was running out of water and thus regulated to 1,000, then realized that he would end up with leftover water and did the final part with an expenditure of 1,200, and then still had a bit leftover so he applied it to the field’s borders… final result for the field: 1,500 liters per hectare.
In the first part, we were left with product deposits far above expected, possibly in conflict with the fulfillment of MRLs for the products’ destination; then we were left with insufficient deposits, possibly leaving us with fewer days of protection and exposed to insect damage. And the final application to the borders also leaves us with unexpected excess product.
It is due to this reality that we began working with calibrations that were as standardized as possible, which was very difficult in the beginning as it required several nozzles in different colors and meant very long application times per orchard. Then, with the help of – and conjoint work with – the people at Peulla, we switched to nozzles that released a higher amount of drops, which greatly simplified the process and left us with only 2 colors and application times of 25 to 35 minutes per hectare.
We can strive to standardize equipment with tractors and nebulizers that are all the same brand and model, but this can also be achieved with tractors that allow us to work at the same speed and with nebulizers featuring pumps that can maintain pressure with the required types and quantities of nozzles, as well as having equivalent air equipment.
This search for standardization is very important since it allows us to have efficiency indicators. This is relevant because, if we know beforehand that for a certain calibration the time in which we will go through a hectare will be 35 minutes, we must do everything in our reach to ensure that the time spent going back to where the pumping ended is as little as possible, and this involves the following:
-Loading docks with available water and in close vicinity
-Trying not to mix different appliers in the same loading docks
-Available products that are in close vicinity
-Roads in good condition
-Fueled-up tractors, with enough petrol to allow them to work through the whole day
-In case the calibration needs to be modified, this should be as simple as possible. The same should be true for pressure changes, gear changes, quick nozzle changes, or switching turning pumps
-A supervisor who is able to deal with minor defects such as broken nozzles or pumps.
All of these points – and others – allow us to make the most out of the time between the moment when equipment finishes an application and when it returns, which can lead to indicators like 1 tank per hour, which is obtained from calibrations with known times per hectare and loading times of 25 minutes; with these 2 parameters we are able to manage our machinery, and therefore know beforehand whether we will be capable of finishing in time with the available equipment, or if we need to change our strategy.
That is how an external requirement, which was initially unpopular, helped us realize that we were being rather inefficient and ineffective in our applications and aided us in standardizing a complex process that depends on people, who in turn are usually lacking in information.
In order to develop management plans for effective and efficient applications, we need to have equipment that has been previously diagnosed, as should be all of the equipment’s components, with their critical elements repaired and replaced, annual and periodic checkups, permanent cleaning, and the availability of highly trained personnel to develop the applications. This will all translate into a successful process, from cultivation to harvesting, with the least possible impact on the environment and humans nearby.