By: Jessie Keith
Clusters of autumn hazelnuts look like brown caps surrounded by green, lacy husks. The sweet nuts are a pleasure to pick for drying, roasting, and winter eating, and the attractive trees and shrubs look beautiful in the landscape.
Hazelnuts (Corylus spp.) are trees and shrubs that originate from temperate regions across the globe. There are approximately 16 species, but only a few are commonly cultivated. Some varieties are largely ornamental while others are bred exclusively for nut production.
Hazelnuts bloom in early spring and their nuts mature by fall. They must be planted in groups of two or more for cross pollination. All are monoecious, meaning a single plant produces separate male and female flowers that are pollinated by wind. The drooping golden male catkins release copious pollen that is caught by the wind to pollinate clusters of small, reddish female flowers. More plantings ensure better cross pollination and fruit production. (Click here for a list of good hazelnuts for pollinizing.)
Hazelnut Pests and Diseases
Eastern Filbert Blight—This is the main disease that American hazelnut growers must battle. This deadly systemic fungal disease attacks European hazelnuts and will kill an otherwise healthy tree or shrub in just one or two years.
It is very easy to identify. Twigs become evenly lined with raised cankers, which look as if a woodpecker pecked along the branches. Diseased branches quickly die, and eventually whole plants will succumb. The best way to beat this blight is to plant resistant hazelnut varieties and species.
Thankfully, Oregon State University has a hazelnut breeding program geared towards developing Eastern Filbert Blight resistant hazelnuts. American growers interested in growing hazelnuts for fruit should rely on their blight-resistant list when choosing good varieties to grow.
Kernel Mold—These include several molds that cause rot in the developing nuts of European hazelnuts. The best course of action is to harvest nuts quickly, keep them dry, and choose resistant varieties.
Filbert Bud Mite—This pest attacks hazelnut flowers in spring—destroying developing nuts. Spraying with an OMRI Listed miticide during flowering time will stop their damage. Some hazelnut varieties are also resistant to this pest.
More hazelnut pests and diseases exist. Click here for an Oregon State University Hazelnut IPM Guide.
Types of Hazelnuts
Most cultivated hazelnuts for edible landscaping originate from Europe and North America. Common hazelnuts (Corylus avellana) are European shrubs or small trees (10-24 feet) that boast lots of exceptional cultivated varieties for home gardeners. Some are ornamental, but most are bred for nut culture. The best-known is the shrubby corkscrew hazel (Corylus avellana var. contorta), which has striking curly branches that look lovely in landscapes and cut flower arrangements. Sadly, this exceptional landscape shrub is blight sensitive. Resistant varieties for nuts include the high-yielding ‘Wepster’ and the vigorous ‘Dorris’, which also bears high yields of very flavorful nuts. Common hazelnut hybrids for nuts, such as ‘Eta’ and ‘Delta’, are also recommended.
The European filbert (Corylus maxima) bears very large nuts. The shrubs or trees (12-33 feet) look great in home landscapes, and there are lots of varieties for ornamental and edible landscaping. The shrubby, purple-leaved ‘Purpurea’ (15 feet) is one of the prettiest. Homeowners interested in more substantial hazelnut trees should grow Turkish hazelnuts (Corylus colurna). The beautiful, large pyramidal trees (40-80 feet) are perfect for home landscapes and produce smaller, sweet nuts in early fall. These blight-sensitive species should be grown in more temperate regions of the American Southwest where Eastern Filbert Blight is not a problem.
The two common North American hazelnut species are both immune to Eastern Filbert Blight. The beaked hazelnut (Corylus cornuta) is a large mounding shrub to small tree (8-10 feet) naturally existing in forest margins and thickets across the northern US and Canada. It develops brilliant yellow and deep red fall leaf color and tasty fall nuts that are obscured by a beaked papery husk. Over time, beaked hazelnuts may sucker to form thickets, so pruning and thinning is required to keep plants looking tidy. California is home to the western beaked hazelnut (Corylus cornuta var. californica), which has broader leaves and increased drought tolerance.
The American hazelnut (Corylus americana) is an eastern shrub (8-12 feet), which forms mounded thickets that become covered with clusters of small, sweet nuts. These wilder shrubs naturally inhabit upland forests and meadows but require more extensive pruning and maintenance, but they develop equally beautiful gold and red fall color.
Full sun is required for best nut production. Well-drained soils with average fertility and a neutral to slightly alkaline pH are preferred. Plant new trees in spring. Make the hole twice as large as the root ball, and amend the fill dirt with Fafard® Premium Natural & Organic Compost before planting. Keep newly planted trees well irrigated for the first month of growth. Water again in the first season during dry spells. It may take two to five years before hazelnuts begin to produce nuts, depending on size at planting time and type.
Apply a mulch tree ring around the base of trees to protect them from mower damage, but refrain from mounding mulch around the trunk. Fertilize established trees in spring with food formulated for fruit and nut trees. (Learn more about fertilizing hazelnuts here.)
Once your plants are productive, you will have lots of fall hazelnuts for baking and eating. You might even want to leave a few for foraging wildlife.
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