Juglans ailantifolia 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. Japanese walnut is distinguished from butternut by its larger leaves and round (not oval) nuts. Prospect Rock Permaculture in Vermont has been backcrossing buartnuts with native butternuts, resulting in 'butterbuarts', which will most likely bear greater resemblance to the butternut parentage, although may also be
Fruit tree propagation cultivars of a single species, known as a family tree, or, within certain limits, cultivars of different fruit species on one tree, often known as a fruit salad tree. Family trees typically combine several cultivars (two or three being most common) of apple, pear or a given species of stonefruit on a single rootstock, while fruit salad trees typically carry two or more different species from within a given genus, such as plum, apricot, and peach or mandarin orange, lemon, and lime. Certain combinations, including sour cherry ("prunus cerasus")/sweet cherry ("prunus avium"), although from the same genus, are known to