 Unlike the closely related and very similar North American butternut, Japanese walnut is resistant to the canker disease caused by the fungus "Sirococcus clavigignenti-juglandacearum".This has led to its being planted as a replacement for butternuts in North America.The two species hybridise readily; the resulting hybrid "Juglans x bixbyi" (otherwise known as "J. cinerea x ailantifolia" or 'buartnut') is also resistant to canker and is likewise planted as a replacement for butternuts.