In the winters of the southern hemisphere, when the orchard seems to be at a standstill, the European hazel tree is already making silent decisions. The female flowers, while the tree is still dormant, expose their stigmas to the cold and prepare the basis for the harvest. which will arrive many months later. When that bloom is perceived as scarce after an extraordinary campaign, the challenge multiplies: maintaining weight and regularity, despite having fewer flowers available.
This text compiles and reorganizes, with a practical approach, the keys shared by advisors and specialists who have been involved in cultivation for years. The reasons for the low flowering, its relationship with alternation (annuality) and, above all, the management that really moves the needle are analyzed.: flower nutrition, fruit set stimulation, phytosanitary protection, precise irrigation and protection against frost and heat waves.
Why is flowering decreasing after a historic harvest?
When the previous season has been very busy, the tree prioritizes filling the fruit and changes its physiology. Excessive load has an anti-inductive effect and alters hormonal circulation., so fewer flower buds are formed, and they also change location. What is usually seen the following year is flowering shifted to the buds at the apex and peripheral areas of the canopy, rather than the more common lateral branches.
This phenomenon is most clearly observed in adult trees that experienced an exceptional campaign. In young orchards or those already in production, this irregular flowering is less noticeable., because last year's load was not as high and the distribution of flower buds remains more normal.
An important nuance is the time of bud formation. The last buds of summer (formed late, in February) partially escape this hormonal interference. This occurs during fruit filling. Therefore, in subsequent seasons, we may find flowers in apical positions of higher potential quality, although in smaller total numbers.
Floral Physiology: What Happens When No One Is Looking
During its winter dormancy, the European hazel tree advances silently. The female flowers expose their stigmas and are ready to receive pollen., activating processes that will continue months later until they become achenes (the "hazelnuts" of each glomerulus). The apparent calm of winter is, in fact, the starting point of the entire productive campaign.
It's not just a question of how many flowers there are, but what each one can hold. The number of achenes per glomerulus is a determining factor: Increasing the average number of achenes from 2,5 to 3,5 results in nearly 30% more production without increasing the number of flowers. This difference is explained by flower quality, the nutritional status of the ovaries, and the ability to prolong the fertility of the ovules.
Alternation and reserves: when the "añerismo" tightens
The alternation in Corylus avellana is a known pattern: one year with a lot, another with little. After a campaign with very high load, the tree is left with depleted reserves, which translates into less flowering in the following cycle if light, post-harvest and support nutrition are not managed well.
The good news is that añerismo can be moderated. Integrated management that combines light (architecture and pruning), post-harvest (reserve replenishment) and adjusted irrigation-nutrition reduces ups and downs and helps stabilize kilos per hectare over time.
Can production be “saved” with few flowers?
With fewer flowers and their distribution shifted to peripheral positions, the scenario changes, but it is not lost. In a standard year, it is estimated that there is around 75% fruit set and about 2,5 achenes per glomerulus.With flowers that are better placed physiologically, this performance can even increase, as long as the garden arrives healthy and well-nourished.
It should be noted that Peripheral buds are also the first to suffer if there are phytosanitary problems. or stress. Likewise, the plant's architecture influences the distribution of photosynthates, water, and nutrients, so an unbalanced canopy penalizes the result even if the flower is "well-positioned."
Immediate management to improve fruit set and number of achenes
To maximize the yield of the limited amount of flowers available, it is important to act on several fronts at once. The priority is to promote early cell division, flower health and transport efficiency. to each glomerulus. These are effective levers:
- Curdling stimulators at the right time, to enhance fruit set and initial retention.
- Foliar-floral supports aimed at the nutrition of the flower and ovary (with a focus on Zn, Mg, K and cofactors), improving the viability of ovules and the quality of the floral structure.
- Root stimulation for continued growth and to avoid the so-called “spring fever” (growth peaks and dips that disrupt domestic demand).
- Preventive plant protection to keep buds and primordia intact from opportunistic pathogens.
In addition to the curd, It is important that the peduncle functions as a supply highwayA well-developed shoot, with good-sized leaves and adequate micronutrient content, is key to sustaining more achenes per glomerulus without subsequent abortions due to internal competition or water stress.
Precision nutrition: strong flowers, sustainable fruits
The hazel flower is demanding even if it doesn't seem so. Zinc and magnesium promote enzymatic processes and tissue integrity., while potassium aids in carbohydrate transport and stomatal regulation. These elements, in balance with NP-Ca and the rest of the micronutrients, fine-tune the reproductive machinery and subsequent filling.
Beyond raw materials, what matters is “when” and “how.” Adjust doses and application times to specific phenological states (pre and post pollination, beginning of active growth, stages of cell division and expansion) marks visible differences in fruit set, size and regularity of the orchard.
Precise irrigation and climate protection: protection against frost and heat
Hazelnut uses less water than other fruit trees, but demands precision. Irregular or insufficient irrigation increases the risk of bacteriosis (Pseudomonas spp.) and fungi such as Botrytis and Monilinia., especially if there are frost wounds or poorly healed cuts that provide an entry point.
In exposed areas of Ñuble, Biobío, La Araucanía and even Los Lagos, Spring frosts can destroy male catkins and female primordia, with very severe fruit set losses. In summer, heat waves cause premature fruit drop and a decrease in size and oil content, two parameters the industry particularly values.
For this growing risk, solutions have become popular: pulse microspray as an active barrier. Suppliers with a long history of agricultural hydraulics have developed specific technologies: Pulsator 205 (low rainfall and high frequency, ideal where water is most pressing) and PulseMax 360 (total coverage and response to extreme heat) systems. integrable into existing lines to minimize additional investmentField trials show less flower damage and more regular yields, with improvements in size.
It's not just equipment: combining active defense with agrometeorological monitoring and real-time operation It's crucial. Digitizing field data and training staff can take full advantage of these technologies and adapt the response to the changing climate.
Garden health: prevent, maintain, correct
Diseases take advantage of the tree's moments of weakness. Bacteriosis and wood and flower fungi find free passage in damaged tissues, so pruning hygiene, rapid wound closure and preventative programs are allies for peripheral buds to reach a successful completion.
Emerging pests are also giving no respite. The bud mite (Phytoptus avellanae) deforms shoots and reduces productivity, so regular monitoring and targeted interventions are part of the minimum package to avoid losing the ground gained through nutrition and climate action.
Plant architecture, light and purposeful pruning
A well-designed canopy distributes light, air and resources better. The architecture of the plant determines the distribution of nutrition to the buds., so pruning is not just about trimming: it is about directing the flow of energy so that the peripheral positions, which this year concentrate the flowers, receive what they need.
In this ambit, “Plant agriculture, pruning and flower induction” approaches are gaining prominenceThe idea is to read the garden after a busy year, bring in light where it's needed, and organize the axes and sides so that next season's floral induction and differentiation have space and resources.
Harvest estimation: changing the chip when the flower changes
If flowering moves to the periphery and there are fewer flowers, the usual estimation methods must be adjustedReference parameters such as “75% fruit set and 2,5 achenes per glomerulus” can vary up or down depending on the location of the flower and the health of the exposed buds.
In parallel, it is advisable to reinforce field observation with real-time climate and soil data (temperature, humidity, water potential), to make more targeted irrigation and application decisions and avoid stress peaks that could lead to set or filling.
Productive context and market: why regularity is worth its weight in gold
In just over a decade, the European hazelnut tree has gone from promise to reality. In Chile, the surface area today exceeds tens of thousands of hectares., concentrated between Ñuble and Los Ríos, with a push linked to international demand (Ferrero, among others) and the possibility of providing counter-season.
This growth is based on the crop's comparative resilience compared to other fruit trees, but it is not invulnerable. In April 2025, late frosts hit the world's largest producer (Türkiye)., driving up prices and highlighting the fragility of global supply. For Chile, ensuring stable and predictable production opens the door to long-term supply agreements.
Cases and technological solutions: pulse microspray in action
With more than three decades of experience in hydraulic engineering applied to agriculture, Specialized companies have promoted pulse microspray solutions to protect flowering and fruit from frost and heat. The Pulsator 205 and PulseMax 360 systems are examples designed to provide water-efficient protection, integrate into existing networks, and operate with intelligent control.
The benefits go beyond a campaign: avoiding massive losses reduces alternation, provides stability to cash flow, maintains grading standards, and, in turn, improves the overall health of the tree by minimizing heat stress and the entry point for disease.
Training, events and knowledge network
Technical transfer is part of the success of the crop. The talk "Plant farming, pruning and flower induction" was scheduled for the 2nd European Hazelnut Conference., led by agricultural engineer Gabriel Aguilar, with 15 years of experience at Agrichile (Ferrero Group) and current experience as an advisor in establishment, management, feasibility and R&D.
The event, held on October 2 at the Hotel Marina del Sol (Chillán), was a meeting point for producers and technicians. In addition to the main presentation, nutrition, irrigation and physiology of the hazelnut tree were addressed., with a focus on achieving more stable productions across seasons, and a registration system was set up for anyone who wanted to attend.
Useful resources and crop cataloging
The technical documentation continues to grow. There is reference material, such as the “European Hazelnut Production Manual”, which provides in-depth information on crop establishment, management, and health. You can find it here: European Hazelnut Production Manual (PDF).
In recent years, the crop has experienced a significant boom in Chile, with thousands of new hectares and growing interest from producers. Within the agronomic classification, the European hazelnut is included among the "nut fruit trees", sharing management challenges with other shellfish species, but with reproductive peculiarities that require a tailor-made suit.
When the previous year has been a record year and flowering has fallen, it's not enough to just cross your fingers. The combination of flower-focused nutrition, fruit set stimulation, preventative health, precision irrigation and active climate protection This allows fewer flowers to yield, resulting in more achenes per glomerule and, therefore, more actual weight. If you add to this a well-thought-out plant architecture and a post-harvest process that replenishes reserves, the orchard is no longer at the mercy of second-fruit bearing and approaches the regularity that the market, and the producer's cash flow, so appreciate.
