Juglans ailantifolia new leaves appear. The female flowers have pink/ red pistils. The fruit is a nut, produced in bunches of 4-10 together; the nut is spherical, 3–5 cm long and broad, surrounded by a green husk before maturity in mid autumn. The edible nuts have an oily texture. The husks are also used to make a yellowish dye. The very bold, decorative leaves and the attractive catkins produced in spring make it an excellent ornamental tree for planting in parks and large gardens. Unlike the closely related and very similar North American butternut, Japanese walnut is resistant to the canker disease
Fruit tree pruning and training can also prevent later injury from weak crotches or forks (where a tree trunk splits into two or more branches) that break from the weight of fruit, snow, or ice on the branches. Some sustainable agriculture or permaculture personalities, such as Sepp Holzer and Masanobu Fukuoka, advocate and practice no-pruning methods, which runs counter to the widespread confidence in the idea that pruning produces superior results compared with not pruning. Many books about fruit-growing assert advantages and disadvantages of pruning or not pruning, although without randomized controlled trials, it is hard to separate theorizing and traditional knowledge from