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 forms whilst keeping the tree short and accessible for harvesting. Other shapes such as cordons, espaliers and fans offer opportunities for growing trees two dimensionally against walls or fences, or they can be trained to function as barriers. Some of the following fruit tree forms require training by tying the branches to the required form. Most require pruning to retain the desired structure. However, not all types of fruit tree are suitable for all forms; apples and pears do well as cordons and espaliers, for example, whereas cherries are more suited to the fan form. An open-centred crown on a short