Black Walnut
Juglans nigra
Deciduous TreeAbout Black Walnut
Black Walnut is a large deciduous tree highly valued for its rich, dark timber and flavorful nuts. It produces juglone, a chemical that inhibits the growth of many other plants nearby. The wood is among the most prized in North America for furniture, gunstocks, and veneer.
Quick Facts
How to Identify Black Walnut
- Compound leaves with 15-23 finely serrated leaflets
- Dark, deeply furrowed bark in a diamond pattern
- Round, green-husked fruits containing a hard-shelled nut
- Chambered pith visible when twigs are cut lengthwise
- Open, rounded crown with stout branches
Care Guide
- Plant away from gardens and sensitive plants due to juglone toxicity
- Water deeply during dry periods to promote nut production
- Prune in late winter; avoid pruning in spring when sap flows heavily
- Harvest nuts after they fall naturally in autumn
- Fertilize young trees with nitrogen-rich fertilizer
Known Issues (3)
Spotted Lanternfly
MODERATEAn invasive planthopper native to China first detected in Pennsylvania in 2014. While it primarily threatens agriculture (grapes, hops, fruit trees), it feeds on over 70 plant species. It excretes honeydew that promotes sooty mold growth.
Affecting 21 regions
Anthracnose
MODERATEA group of fungal diseases causing leaf spots, cankers, and shoot blight on many shade trees. Sycamore, dogwood, maple, and oak are commonly affected. Cool, wet spring weather promotes infection of newly expanding leaves.
Affecting 38 regions
Thousand Cankers Disease
HIGHA disease complex involving the walnut twig beetle and an associated fungus that has caused significant mortality of black walnut, particularly in western states. Thousands of small cankers coalesce to girdle branches and the trunk.
Affecting 15 regions