European hazelnut (Corylus avellana) is now well established from Maule to Los Lagos. Beyond climate and management, the health and genetic quality of nursery plants determine the resilience and productive potential of the mature orchard. That’s why at Vivero El Avellano we take prevention and diagnosis seriously: starting with healthy, vigorous plant material makes everything that follows easier, from planting to postharvest. Our two-year plants are delivered with training pruning already done. Their vigor promotes strong laterals in the nursery, which explains earlier entry into production and higher yields from the second year after planting.
Lower initial inoculum pressure and better healing of training wounds
Robust roots that better tolerate moisture fluctuations and reduce collar rot risk
Balanced architecture for improved canopy ventilation and lower canker risk
Rigorous agronomic and health quality control, removing plants that do not meet Vivero El Avellano standards
2. Plant health overview by zone
Climatic and soil conditions vary significantly between producing regions, directly influencing the incidence and severity of European hazelnut diseases and pests.
Maule–Ñuble
Greater presence of clayey soils requires raised beds to avoid excess moisture at the root zone. European hazelnut, despite having a very shallow root system, is highly sensitive to excess moisture. This causes plant stress, increasing predisposition to fungal root diseases and bacterial diseases in the canopy. Any measure that reduces root-zone moisture helps achieve a healthier, more productive, and longer-lived orchard.
Biobío–La Araucanía
More humid spring climate requires preventive measures to avoid or reduce bacterial diseases (Xanthomonas). During budbreak, copper applications protect the moment buds open, a risk window for pathogen entry. Training and production pruning should be done without rain or drizzle, and at least three days after rainfall, to reduce inoculum in the environment.
Los Ríos–Los Lagos
More frequent humidity; greater emphasis on the measures described for the previous region.
At Vivero El Avellano, we suggest adjusting management and the health plan according to farm microenvironments (orchards in lower areas have greater predisposition to frost damage and higher humidity in soil and canopy, etc.).
3. Main European hazelnut diseases
3.1. Wood diseases (cankers and dieback)
Increasingly, wood diseases have become present in orchards. This occurs as more adult orchards appear and the responsible fungi are identified. The main cause is the presence of wounds, especially pruning during periods of high inoculum in the environment, as well as aggressive unprotected cuts. Plants can also originate infected from the nursery with wood fungi due to inappropriate nursery location in harsh climates and pruning practices with high inoculum presence.
Management: Avoid pruning during rain or drizzle or high relative humidity. Protect pruning cuts. Start planting with plants from recognized nurseries with proven experience, such as those from Vivero El Avellano.
3.2. Phytophthora collar and root rot
Phytophthora rot
Visible Phytophthora symptoms in European hazelnut
Clay soils with poor drainage, high water table, etc., cause root asphyxiation. Hazelnut does not tolerate root asphyxiation. Extreme moisture conditions cause the death of young plants due to Phytophthora; however, older plants may tolerate excess moisture longer, but the stress caused by this condition results in a significant loss of productive potential because it requires energy through inefficient metabolic mechanisms.
Prevention: Use raised beds in soils where there is doubt about moisture management. Remember there is only one moment to make this decision. Improve drainage with all possible practices.
The main bacterial disease in European hazelnut, especially in the southern zone, due to colder, wetter springs. Symptoms include death of buds, twigs, and branches, with branches appearing without lateral twigs. The main cause is pathogen entry through natural wounds, such as leaf fall in autumn and bud opening in spring, which creates a pathway into the bud. Plants can also come infected from the nursery due to poor management during training; hence the importance of obtaining top-quality plants such as those from Vivero El Avellano.
Prevention:Copper application at leaf fall and later during budbreak. Avoid plant stress. Start planting with plants from recognized nurseries with proven experience.
3.4. Brown spot on fruit (physiopathy)
Not linked to a single pathogen; it is associated with microclimate, canopy ventilation, fruit load, and water management. Keys: airy canopies with adequate training pruning, stable irrigation (no extremes), and load management to maintain size. Balanced nursery plants simplify this control.
4. Agronomic, sanitary, and prevention calendar
Below are some general management practices to implement. Plant health management should follow a schedule based on the phenological and climatic conditions of each producing region.
4.1. Annual schedule
Dormancy (Jun–Aug): after planting, continue training pruning and production pruning in older orchards. Protect wounds and avoid cuts on rainy or drizzly days and for at least three days after rain. Check drainage and water accumulation in low areas. During winter, root damage from excess moisture can occur, especially in young plants with limited root development. Symptoms appear in spring during budbreak because the plant demands water and nutrients but cannot translocate them due to root damage.
Budbreak (Sep): this is the period of greatest sensitivity to bacterial entry. Bacteria can only enter internal tissues through natural openings. Therefore, when buds and leaves open, protect with copper applications.
Spring (Oct–Nov): continue monitoring budbreak (depending on the zone) and protection with copper applications. Monitor hazelnut aphid (Myzocallis coryli) and control. Sucker control. Weed control, fertilization, irrigation.
Summer (Dec–Feb):proper irrigation management, agronomic practices such as weed control, sucker control, fertilization, chemical applications for insect control (leaf-footed bug), soil insects, etc. Keep inter-rows free of weeds and pruning residues to facilitate harvest. Prepare harvest machinery.
Harvest - postharvest (Mar–Apr):store fruit in clean, ventilated areas.
4.2. Prevention checklist
A preventive plant health program is the foundation of sanitary success.
Well-drained orchards: do not establish orchards in low-lying areas or where drainage issues cannot be improved and resolved.
Drainage: (surface/subsurface). In clay soils, use raised beds at least 50 cm with settled and finished soil. The bed will drop at least 20–30 cm after construction.
Pruning with immediate protection (paint), never during rainy periods and at least three days after rainfall.
Frequent disinfection of pruning tools.
Burn all pruning residues, especially branches and twigs with disease symptoms.
Remove stumps of poplars, willows, acacias, or hazelnuts and any vegetation deteriorating in the orchard. Fungi from these species are not specific and can develop on different species; reproductive structures can infect wounds in wood (pruning cuts, etc.).
Sample and send tissue to the lab if in doubt.
Start orchard establishment with healthy plants. At Vivero El Avellano we ensure optimal sanitary standards.
5. Quick field diagnosis
Early diagnosis allows corrective measures before diseases or pests cause irreversible damage.
Plants that are slow to budbreak in spring compared to the rest of the orchard. When they do, leaves are more yellow than on other plants. Check the plant collar by scraping the bark at soil level with a sharp blade. Dark tissue presence indicates likely Phytophthora. A plant damaged by this fungus is difficult to recover. Determine the cause: excessive irrigation, poor drainage, etc.
Dieback of twigs in parts of the tree (bare twigs without leaves). Likely Xanthomonas. Bacterial damage is common in lower orchard areas. Young plants are more sensitive to bacterial attacks. Protect with copper applications at leaf fall and budbreak.
Cankers: branches dry out. Likely wood fungi. Protect cuts with paint. Burn pruning residues and stumps of other species.
Quality tips: Plants with a balanced structure, good root system, well-lignified, and with training pruning completed are more likely to recover from minor management issues after planting. A weak, stressed plant shows delayed establishment, higher losses, and lower productive potential over the orchard’s life.
Specialized technical advisory
Our expert team supports you at every stage of your orchard’s health management
