Hazelnut Harvest in Croatia: How to Build an Efficient Mechanized Workflow

In register data of 2018, Istarski duguljasti covered 60% of Croatia's hazel area and Rimski 26%. A review by Croatian fruit researchers describes Istarski duguljasti as a steady cropper whose kernel shape does not meet the confectionery industry's needs and whose long husks hinder cleaning in mechanized harvest, while Rimski gives steady, high yields and a round nut that falls easily out of the husk, which suits mechanized harvest and the confectionery industry.

The review adds that most orchards grew on their own roots, raised from root suckers, while a smaller share was grafted on Turkish hazel (Corylus colurna); it advises using only declared planting material. The most common training form was a modified bush vase; newer orchards used single-stem trees and denser planting meant to ease machine harvest. In the mechanized system this guide follows, trees are not shaken, so Oregon State University (OSU) advises making the floor as smooth as possible at least a year before the first commercial harvest.

The review estimates that about 10% of the trees stand on unsuitable terrain and links fruit drop and empty nuts to low temperatures during fertilization, above all on low ground and in frost pockets. In February 2012, temperatures in Baranja fell as low as -26 °C, and a 2021 thesis based on a survey of 21 growers reports losses of up to 100% in lowland orchards. OSU explains that hazelnut cannot set nuts with its own pollen, and a 2022 thesis names Rimski as the main pollinizer of Istarski duguljasti in Croatia.

A 2009 extension article put hazelnut's needs at 700 to 800 mm of rain a year and noted that irrigation systems were then being installed in modern intensive orchards; no source found gives the share of irrigated orchards. Dry months occur: the Croatian Meteorological and Hydrological Service (DHMZ) rated August 2024 extremely dry at Osijek, with 7 mm, and September 2025 very dry in most of eastern Croatia, and a 2021 thesis notes that summer drought, above all in June, leaves nuts small with a low kernel yield.

EPPO lists the brown marmorated stink bug (Halyomorpha halys) as present in Croatia with a restricted distribution, first found in 2017. Monitoring in 2022 caught it in hazelnut orchards, most at Tovarnik, with 79 individuals, although no fruit damage was observed at the sites studied. Farm reports do not name the species: on a farm at Bizovac, stink bug damage showed as discolored kernels at cracking in 2019, below a level that would hurt market value, and in 2025 a grower said about 30% of the damage came from stink bugs alone.

The review reports a tendency to remove root suckers, and a 2022 thesis calls pruning especially important. Hazel planting material is checked for seven regulated pests, among them big bud mite and bacterial blight, with a 0% tolerance (Croatian Agency for Agriculture and Food). In single-stem orchards planted for machines, the ID DAVID SURFEED spreads solid manure, the ID-XL weeds the tree row, the Mañez Lozano Mega Twister S6 sprays tall, dense canopies and the ID-REX disc pruner makes lateral and topping cuts.

Croatian sources give few harvest details. A 2021 thesis says growers with smaller orchards collect the crop by hand; a 6.5 ha farm at Bizovac used a tractor vacuum that also ejected empty nuts (2020); and a 2009 extension article said intensive orchards were harvested with modern machinery. A 2023 thesis places the harvest from late August to early October. In single-stem orchards planted for machines, mechanized harvesting can bring the crop in on time, with less risk of nuts deteriorating while they wait.

In the mechanized system this guide follows, as in Oregon, the trees are not shaken: OSU explains that the thin-barked, shallow-rooted trees would be damaged. The nuts drop onto a leveled, flail-mowed floor, then are swept and picked up in several passes; a 2022 thesis notes that in some cultivars not all nuts ripen at once. At Osijek, rain averaged 59 mm in August and 56 mm in September over 1899 to 2024, but September brought 112 mm there in 2024 and only 19 mm in 2025 (DHMZ).

Flory harvesting machinery is available in Croatia through OVE Europe for single-stem orchards planted for machines. The self-propelled Flory V62 Sweeper sweeps the nuts into windrows, and the self-propelled 8772 Harvester picks them up; Flory lists a mud brush as standard for hazelnuts on the 8772. The 1500 Conveyor Cart receives the nuts, the ST14 Shuttle carries them and the 4840 Field Elevator loads trailers for the processing site.

Croatian sources say little about drying: engineering theses advise husking after the nuts have dried a little rather than right after collection (2021), and describe drying at up to 40 °C until moisture falls to the usual 10% (2023). The review, with data to 2018, noted that most Croatian production was not standardized and was very uneven in quality, that most growers sold at local events, at the farm gate and at markets, and that the confectionery industry relied mainly on imported kernels.

Husk removal depends on the cultivar: in Istarski duguljasti the nuts do not fall out of the husk by themselves at ripeness (a 2023 thesis), while Rimski's round nut falls out easily. In British Columbia's guide, nuts are husked, cleaned, washed, sanitized and dried to 5 to 8% moisture within 24 hours of harvest, and the Codex code of practice for tree nuts advises storage below 70% relative humidity and at 0 to 10 °C, both where possible.

As an EU member, Croatia applies Regulation (EU) 2023/915: 5.0 µg/kg of aflatoxin B1 and 10.0 µg/kg in total for hazelnuts for the final consumer or used as an ingredient, and 8.0 and 15.0 µg/kg for nuts to be sorted first. Jessee, whose processing lines OVE Europe supplies, builds drying, in-shell cleaning and sizing, and shelling systems, and it established product lines for hazelnuts in the 1980s.

For general information only. Information may become outdated and does not replace site-specific professional advice. Consult a qualified agronomist and confirm equipment suitability with OVE before acting.