Chinese white san pears (Pyrus pyrifolia and p. ussuriensis) are fast-growing trees that produce round crisp pears. They are susceptible to most of the diseases suffered by the European species of the pear genus Pyrus. They especially suffer from the fungal diseases pear scab, powdery mildew and sooty blotch. Asian pears may be grown in plant hardiness zones 5 through 9