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Ministry of Agriculture, Food and Rural Affairs

HEARTNUT WALNUTS

Other Common Names Include:

Japanese Walnut

Latin Name: Juglansailantifolia var. cordiformis

Plant Family: Juglandaceae

Close Relatives: Japanese walnut,Butternut, Black walnut, English walnut

Uses and Markets: Culinary (e.g. Valentine’s chocolates, candies and cakes); Industrial (e.g. shells can be used for mulches, crafts and air blast materials); Ornamental

Grafted heartnut trees (Source: S. Westerveld, University of Guelph) Female heartnut flowers (Source: S. Westerveld, University of Guelph) Male flowers (catkins) of heartnut are similar but slightly smaller than the black walnut catkin pictured in this photo Hearnut cluster

Spring frost damage to hearnut (Source: S. Westerveld, University of Guelph)
Agronomics
Production Life Cycle in Ontario

Perennial

Hardiness Zone

6

Special Notes

The trees are hardy to Zone 5 but production in Zone 5 is limited by spring frosts that kill the developing flower buds. The heartnut is a sport (natural mutation) of the Japanese walnut with heart shaped nuts. Pollination is improved by planting two or more varieties.

Propagation method

Transplant of potted or bare root trees propagated from seed or grafting onto butternut or black walnut root stock.

Greenhouse Seeding/Propagation Dates

Spring

Field Seeding Date:

N/A

Field Transplanting Dates

April to May

In-row spacing

6 - 8m

Between row spacing

6 - 8m

Optimal Soil temperature at planting

>10°C

Fertility

No current Ontario fertility recommendations exist. Research and recommendations from outside Ontario do not necessarily apply to Ontario growing conditions. No research has been conducted into the nitrogen requirements of heartnut  Click here for phosphorus and potassium application guidelines and for more information on specialty crop fertility.

Soil type

Well-drained soils, moist sandy loam to clay loam soils.

Soil pH

6.0-7.0

Special requirements for growth habit

None

Optimal Temperature Range

12-30°C

Temperature sensitivity

Freeze tolerant (trees); frost sensitive (flowers).

Irrigation requirements

Irrigation beneficial under normal Ontario conditions.

Days to harvest

Nuts produced as early as 1 to 3 years for grafted trees, but commercial production begins in 6-8 years.Takes 140 days from flowering to nut maturity each year.

Specialized equipment

Dehusking drum, pruning equipment/platforms, air-blast sprayer, nut cleaning, dehydrators, cracking, sorting.

Harvest

Early to late September.

Harvest Scheduling

Single harvest

Hand harvest or machine harvest

Machine harvest for large plantings; hand harvest for smaller plantings.

Quality parameters/grades

No established grades. Quality is determined by the market. Due to variability in seeded trees, cracking quality is variable. Marketable nuts must be able to crack easily.

Additional Harvest Notes

Nuts are normally allowed to fall to the ground and are picked up with hand-held or larger equipment.

Post harvest
Special handling/curing

Shell nuts and dehydrate kernels before long-term cold.

Storage Conditions

Relative humidity (RH): Low humidity will prolong shelf-life.

Temperature: <0˚C.

Air Exchange: N/A

Duration: Up to 2 years if frozen

Pests
Specific pests observed on this crop in Ontario (observations based on limited experience with this crop)

Insects and Invertebrates: Butternut curculio, walnut husk fly/maggot, codling moth, leafrollers, leafhoppers, aphids, scale, Japanese beetle, pale green weevil

Diseases: Walnut bunch disease (witch’s broom), crown gall, butternut canker (stressed trees), walnut blight (Xanthomonusspp.)

Other: Squirrels, birds (especially grackles), deer

Other Potential Pests: The following pests have not been observed on this crop in Ontario. However, they are either significant concerns for closely related plants in Ontario, or are reported on this crop in other production areas. This is not a comprehensive list of all potential pests. Not all of these pests will necessarily survive Ontario’s climate, but could potentially survive in a protected environment (e.g. greenhouse, storage facility).

Insects and Invertebrates: Mites, brown marmoratedstink bug

Diseases: Walnut weevil (Conotrachclusjuglandis)

Other:

*Indicates pests commonly mentioned as causing significant damage or economic loss to this crop in other regions.

Comments

To date the following pests have been the most significant in Ontario: butternut curculio, husk maggot.  For more information on Crop Groups, refer to the Pest section. Always refer to product labels, and follow all directions specified on the label, before applying any pest control product.  For more information, consult an OMAFRA specialist.

	Wilting of the developing shoot due to leaf roller feeding (Source: S. Westerveld, University of Guelph) A leaf roller caterpillar inside a young heartnut shoot (Source: S. Westerveld, University of Guelph) Butternut curculio adult.Maturing larvae of butternut curculio and associated damage to nutHeartnut fruits with butternut curculio exit holes at the tips (Source: S. Westerveld, University of Guelph)Adult husk maggots emerge in late July to mid-September to lay eggs on heartnut.Walnut husk maggot feed on nut husks.  Juices and fly excrement from the rotting husk can seep to the kernel affecting flavour and hygiene.Bacterial blight on heartnut leaf
Additional Notes

A recommended ground cover for Heartnut trees is Dwarf perennial rye.

Ontario Research Projects Used to Create This Profile

Cultivar research trials – The University of Guelph, at the Simcoe Research Station and the Vineland Research and Innovation Centre, is testing several dozen cultivars of hazelnuts to determine suitability for fresh market and confectionary markets, tolerance or resistance to Eastern Filbert Blight disease, which has prevented commercialization in Ontario previously, cold tolerance during winter, frost tolerance in spring, cross-pollination to maximize cropping, pest management program development.

Minor use registration – Agriculture and Agri-Food Canada at Harrow is conducting field trials to achieve minor use registration of herbicides for use on Hazelnuts in Canada.  Field trials for minor use registration of insecticides, fungicides and biological pest control will be included in the future.

Hazelnut pest management – OMAFRA Crop Specialists. Surveys and timely site inspections at private hazelnut farms and hazelnut research sites are conducted to develop an effective pest management program for Ontario.  

References
  1. Leuty, T, D. Galic, P. Bailey, A. Dale, E. Currie and M. Filotas. 2012.  Hazelnuts in Ontario – Growing, Harvesting and Food Safety.  Ontario Ministry of Agriculture and Food and Ministry of Rural Affairs Factsheet #12-011,  Agdex 240. 
  2. Dale, A, D. Galic, T. Leuty, M. Filotas and E. Currie. 2012. Hazelnuts in Ontario - Biology and Potential Varieties. Ontario Ministry of Agriculture and Food and Ministry of Rural Affairs Factsheet #12-007, Agdex 240. 
  3. M. Filotas, A. Dale, D. Galic, T. Leuty, E. Currie 2012. Hazelnuts in Ontario – Pests. Ontario Ministry of Agriculture and Food and Ministry of Rural Affairs Factsheet #12-009, Agdex 240.