The contorted hazelnut tree (Corylus avellana "Contorta") -- sometimes called Harry Lauder's walking stick for its British discoverer -- bears aptly descriptive names. This upright, 8- to 10-foot intricately twisting shrub brings yellow spring blooms and deciduous pale-green leaves to landscapes across U.S. Department of Agriculture plant hardiness zones 3 through 9. The plant is at its best with winter sun backlighting its corkscrew limbs. Its problems include vulnerability to eastern filbert blight, aphids and leafrollers. Contorted hazelnut compensates for its lack of edible nuts by contributing those curiously bending twigs to floral designs.
Water a newly planted hazelnut to keep its soil consistently moist during the first year. After that, water it thoroughly whenever the top 3 inches of soil are dry. Light watering leads to shallow roots incapable of absorbing moisture in dry periods; heavy watering develops roots deep enough to survive dry surface soil.
Fertilize trees 2 years or older with actual nitrogen, applied as urea. Feed at bud break, when half or more of the leaves have begun opening. Urea contains 46 percent actual nitrogen. A 2-year-old tree requires 2 ounces of actual nitrogen, or slightly more than 4 ounces of urea. Increase the ratio as the hazelnut grows. Plants 12 years or older need 24 to 32 ounces of actual nitrogen. Always apply the urea according to the manufacturer's specifications.
Remove dead, broken or diseased branches, cutting right above a healthy leaf node with sharp pruning shears or branch loppers. Remove twigs and branches that rub against each other. Their wounded bark invites insect and disease infestations; thinning them also opens the tree's interior to more light.
Trim excess lower branches to create a treelike appearance showcasing the twisted upper growth. Remove new branches emerging from any interestingly shaped limb joints. Manually rub the growth eyes that produced the branches to prevent their resprouting and concealing the joints.
Pull root suckers as soon as they appear. As a cultivar, contorted hazelnut typically grows grafted onto rootstock from another Corylus variety. Root suckers won't develop twisting branches, and they'll rob the desirable ones of water and nutrients. Pulling them by hand gets more of the growth-eye tissue than cutting them.
Examine upper branches in early summer for the raised bumps of eastern filbert blight. They’ll eventually burst to reveal white fungal masses before turning black. Lop the infected branches back to 3 feet below the bumps and burn or bury them. After cutting, sterilize your pruning tools in a solution of one part household bleach to nine parts water.
Check the shrub for insects. Greenish-yellow, pearlike filbert aphids suck sap from new stems and leaves. Wash them off with a strong blast of water. Green, brown-headed green filbert leafroller and yellow, black-headed obliquebanded leafroller caterpillars feed on foliage woven shut with white webs. Remove and dispose of infested twigs, or pinch the leaves to crush the pests.
Things You Will Need
- Hose or watering system
- Urea fertilizer
- Pruning shears
- Branch loppers
- Household bleach (optional)
- Fine Gardening: Corylus Avellana "Contorta"
- Dayton Nurseries: Walking Stick
- Missouri Botanical Garden: Corylus Avellana "Contorta"
- University of California Integrated Pest Management Trees and Shrubs: Filbert, California Hazel, Hazelnut -- Corylus spp. Family Betulaceae (Birch Family)
- Oregon Hazelnuts: Nut Growers Handbook
- Samuel Roberts Noble Foundation: Fertilizer...Buy the Numbers
- Planters Place: Gardening Tip -- Pruning Contorted Filbert Trees
- Oregon State University: Detecting and Controlling Eastern Filbert Blight
- Washington State University Extension: Filbert: Filbert Aphid
- Washington State University Extension: Filbert: Filbert Leafroller