Use of dormancy breakers: requirements and objectives

Use of dormancy breakers: requirements and objectives

Before making the decision, check all the information
Dormancy Breakers

Advance, homogenize or standardize harvest and flowering are some of the effects that can be achieved with the use of dormancy breakers. Its use is usually a recurring topic of conversation among producers, especially if they need to reach international markets with their fruit on specific dates.

The use or non-use of dormancy breakers must be decided taking into consideration a prior evaluation of each season; The different factors that intervene in the optimal productive potential of an orchard must be taken into account, such as the agro-climatic, logistical-operational and commercial indicators that determine the objectives sought by each producer. The decision must always be consistent with the vision that the producer has and what hopes to achieve.

The appropriate use of dormancy breakers, considering that certain requirements must be met for their application, may allow an earlier and/or uniformity of harvest and flowering, which, added to other seasonal factors, could eventually translate into a better garden profitability.

It should be taken into account, for example, that for the application of dormancy breakers, each variety must have reached at least 70% accumulation of chill hours, according to its specific requirements. Royal Dawn, for example, needs 400 to 500 hours of cold, while Kordia at least 800-900 hours, based on the classic model of accumulation of chill hours, that is, below 7.2 ºC.

But in addition to the requirements, there are other questions; What type of dormancy breaker to use, how to know if the orchard is in appropriate conditions to carry out this intervention of the phenological state of the cherry tree, what risks does it bring and how to know if the results will be as expected?

There are many questions that may arise regarding dormancy breakers and the commercial decision to use them; However, there are several aspects that must be taken into consideration. First, the decision to advance phenological stages, such as flowering, fruit set, and harvest, mainly for early varieties and in early areas to advance or partial out part of the surface of an orchard, in the event that there is a large extension of surface; Second, also to advance or synchronize varieties that need to be pollinated with another variety, or “simply” based on a commercial decision or a personal vision of each producer and their strategy.


One strategy is the use of Hydrogenated Cyanamide, a product that allows advancing phenological stages and harvest, and on the other hand, today there are alternative dormancy breakers (DB) (harmless for the plant and the operator) that are not necessarily characterized by advancing initial phenological states. 

These dormancy breakers (DB) emerged in response to the suspension, more than a decade ago, of the use of Hydrogenated Cyanamide in the European community and are currently used separately or together, considering that Cyanamide generates great action on the advancement of the phenological and harvest states; while dormancy breakers (DB) play a main role in the synchrony or homogenization of these states.

Hydrogenated Cyanamide or Dormancy Breakers?

The application strategies for hydrogenated cyanamide or DB depend exclusively on the objectives for each orchard, considering the area in which it is located, the climate, correct application of the products and the calibration of the machines with which it will be carried out, among other factors.

Hydrogenated Cyanamide is undoubtedly the best tool to advance flowering; However, DBs have a unique characteristic: they homogenize and synchronize flowering, which generates great benefits from a productive perspective, since they help nutritional, phytosanitary or growth regulator programs to be more efficient.

The fundamental thing is that the decision of the strategy to be used, whether with Cyanamide or DB, is based on as much information as possible. With the information available today, it would not be incorrect to say that hydrogenated cyanamide alone generates great action on the elevation of phenological states, while the alternative DBs have a great participation in synchrony, rather than in advancement. 

But the final decision to use it must be accompanied by a clear strategy that truly benefits production and does not put it at risk. Many times it is mistakenly believed that its direct application will be effective and will allow greater profits in the season, however, there are many factors that influence and determine the success or failure of the production of an orchard. The results? They will be seen in the next 3 or 4 months.

It must also be taken into account that the applications of Dormancy Breakers can generate greater risks of damage from spring frosts in the flower primordia and in the case of buds, it can cause the death of the vegetative bud, which would be detrimental to the renewal of this reproductive organ.

The phenological stage of greatest care is that of swollen bud, where the plants are more sensitive to cold damage. This makes it necessary that in the event of episodes of low temperatures (<-0.5ºC for more than one hour), frost protection systems are required.

Another aspect to consider is that although the use of these strategies allows earlier flowering, this does not mean an earlier harvest day. For example, an advance of 10 days in full flower does not translate into 10 days less harvest, but rather 5-6 days; Meanwhile, in a season with very good cold accumulation, an advance of 20 days in full flower could become about 10-12 days less harvest.

This was corroborated in a study carried out by the Avium team in Chile, in relation to the impact of dormancy breakers on the advancement of harvest and flowering concentration; For this, 50% hydrogenated cyanamide (HC) and alternative dormancy breakers (DB) (Fiore® and Erger®) were used in the 2015/2016 season of the Santina variety. The objective of the trial was to evaluate the different strategies to verify if it is possible to achieve homogenization of the initial phenological states of the cherry and, eventually, achieve a significant advance in the harvest, which would result in better profitability in production.

Finally, it should be noted that the decision to use DB must be accompanied by a clear strategy that contributes to production and in which ideally there are no risks that could affect the initial objective. How and when to use them, whether hydrogenated cyanamide or a dormancy breaker, becomes a fundamental decision that depends on several requirements that will define the success or failure of this commercial strategy and, as a consequence, will determine the productive potential of the orchard.

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