Walnut Harvest in Türkiye: Timing, Logistics & Mechanized Workflow

Two walnut systems exist side by side. In 2013 the Atatürk Horticultural Central Research Institute at Yalova described most of the tree stock as seed-grown, and a 2017 paper traced Turkish walnut production to trees, mostly seed-grown, scattered along streams and in vineyards and gardens. Grafted block orchards are spreading fast: TEPGE puts the rise in walnut orchard area at 156% from 2014 to 2024. Denizli had the largest area in 2024, and Denizli, Bursa and Kahramanmaraş the largest crops.

Late spring frost is the most important limit on walnut production, the Yalova institute says: flowers can be damaged at -1 °C. Frosts hit Malatya in April 2014, Kaman in 2014 to 2016 and Oğuzlar (Çorum) on 11 April 2025. The Ministry's 2020 orchard guide advises planting on slopes more than about 15 m above the foot of the slope, so cold night air drains away, and the Yalova institute recommends Gültekin-1, Yavuz-1 and Şebin for late-frost areas.

Turkish guides mostly give spacings from 7 x 4 m to 10 x 10 m, closer for lateral-bearing cultivars and wider for terminal bearers, with pollinizers no more than 50 to 90 m away. For machine harvest, the Yalova institute asks for spacing that allows it and a trunk of at least 1 m, and the Ministry guide puts the first main branch 1.5 to 2.5 m above the ground. Grafted trees start bearing at about 4 to 5 years (Gaziantep directorate).

A commercial walnut orchard must be irrigated, preferably by drip (Alata Horticultural Research Institute, 2022). Yalova guidance puts the yearly water need of a full-bearing orchard at about 1,200 to 1,350 mm, part of it from rain, with drip or mini-sprinklers every 4 to 8 days; no Turkish walnut irrigation trial was found, so these figures are guidance. Heat above 38 °C can cause sunburn and kernel shrivel (Alata, 2022).

The Ministry's 2018 walnut integrated pest management instruction names anthracnose and codling moth as the main problems and reports bacterial blight in all walnut areas, above all the Marmara region. It counts two codling moth generations on walnut, while a Kahramanmaraş study found three (2012 to 2013), and it sets control at a trap catch of 6 moths in total over two consecutive weeks in the overwintering generation, 3 a week in summer generations, or 2% infested fruit in 500 fruits from at least 20 trees.

The instruction links sunburn mainly to wrong pruning that exposes nuts at ripening. Against blight it asks for pruning that lets air through the canopy and no excess nitrogen, against anthracnose for fallen leaves to be removed in autumn, and it calls for leaf sampling every July. Walnut husk fly is not covered by the instruction, and EPPO's distribution table does not list Türkiye.

Walnuts in Türkiye have traditionally been knocked down with poles and gathered by hand. Yalova, Alata and Gaziantep guidance advises against poles, and the Yalova institute warns that they break the shoots that carry the next crop. In Denizli's modern orchards, the provincial directorate said in 2024, machines make harvesting easier and faster. Harvest generally runs from mid-September to late October, with Maraş 18 in the first half of September, Fernor in September and Chandler in late September or October (Ministry guide, 2020).

The Ministry guide marks kernel maturity by the packing tissue between kernel and shell beginning to brown, and the Yalova institute warns that waiting for split hulls, as traditional harvest does, means harvesting 2 to 3 weeks late for kernel quality. The Ministry guide also warns that nuts left long on the ground darken and suffer heat damage, worms and mold. In block orchards laid out for machines, a mechanized line lets each block be shaken and picked up on time, so nuts spend less time on the ground.

In a 2009 to 2010 trial on 12-year-old trees, a trunk shaker took 2.8 to 4.2 minutes per tree and dropped 76 to 86% of the nuts; poles dropped 94 to 98% but took 82 to 97 minutes. Flory harvesting machinery is available in Türkiye through OVE Europe: a line runs from the VR700 Shaker, 34 Series Sweeper and 860 Harvester (the 490 is a smaller option) to the 1500 Conveyor Cart, ST14 Shuttle and 4840 Field Elevator, with the CP87 Conditioner optional.

Hulling is difficult, costly and labor-intensive, the Yalova institute notes. In its trials, a drum huller with water spray hulled 96.7 to 98.3% of the nuts in 12 minutes per 100 kg batch, and the water kept shells from darkening; mature nuts whose hulls have not yet split are very hard to hull. Nuts to be sold in shell should be dried right after hulling (Ministry guide, 2020).

Most Turkish growers dry walnuts outdoors in the shade, and the Ministry's guide calls drying in direct sun wrong because kernels darken. In the Yalova institute's dryer trials (2008 and 2009), air at no more than 40 °C dried nuts to 7 to 9% moisture in about 20 hours instead of 7 to 10 days, with quality closest to fresh nuts. Jessee, whose processing lines OVE Europe supplies, builds walnut hulling lines and drying, in-shell cleaning and sizing, and shelling systems.

Turkish standards TS 1275 (walnuts in shell) and TS 1276 (kernels) are listed for commercial quality inspection, and maximum levels for contaminants, mycotoxins included, are set by the Turkish Food Codex contaminants regulation, updated in November 2023. Many growers sell in shell: in a Kaman survey published in 2017, nearly 9 in 10 did so, which the authors attribute to buyer demand and a shortage of labor for cracking.

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.