An outline is given for the sub-tropical members of this large group, namely apricots (P. armeniaca), peaches and nectarines (P. persica) and Japanese plums (P. salicina), abbreviated as AP, PN and PL respectively, as opposed to the more temperate zone fruits such as cherries and European plums.
All native to China.
Best grown where summers are warm and dry and the hazard of spring frosts is low. They do not tolerate waterlogging but have some tolerance of drought. Perth and coastal surrounds get <400 chill hours each year, so varieties selected should have chill requirements below this level to flower and fruit successfully.
They are all small deciduous bushy trees, 4- 8m high. PN leaves are deep green, long and thin, PL mid-green, elliptic and AP mid-green, broadly oval.
Rosaceae Family. There are hundreds of fruit tree species in the genus Prunus, plus also many inter-specific hybrids eg plumcots.
Prefer light deep soils with good drainage. Avoid heavy clays and wet soils
Mainly by budding. AP and PN seedlings are commonly used as rootstocks, and dwarfing rootstocks are also available.
Cultivar performance is very much influenced by environment, so the best strategy in selection from the many available is to choose those that are known to fruit well locally.
Flower buds are produced usually on one-year-old shoots, plus in AP and PL on spurs on older wood. The individual hermaphrodite flowers all have 5 sepals, 5 petals, numerous stamens and a single carpel. In spring, flower buds open first followed by leaf buds. Important PN varieties are self-fertile, AP mainly so, but most PL require cross-pollination. They are insect pollinated, usually by bees, with wind playing a small part in some.
All 3 species require adequate nutrition for quality fruit and yield, with PL less demanding than the other two. Adequate watering should be given during fruit growth through to maturity.
Tolerance is moderate.
They are most commonly grown as an open vase, so when young, 3-4 well-spaced scaffold limbs should be selected for the main framework. With mature plants, size should be limited for ease of pruning, harvesting and spraying. Each year 1 year old shoots should be shortened and thinned to encourage development of new fruiting shoots along the whole length of scaffold branches. Light penetration throughout the canopy should be maintained. In most cvs, blossom and fruit will need to be thinned.
These trees also can be espaliered, a method that is very productive in a small space, and that can more readily protect the fruit from birds with netting.
All produce drupaceous fruits where the edible portion consists of a fleshy exocarp and mesocarp surrounding a stony endocarp (pit or stone) containing a single seed. AP are freestone, PN free- semi- or clingstone and PL usually clingstone. AP flesh is orange, PN white or yellow and PL yellow-dark red.
Time to first harvest is 2-4 years, with full production of AP and PN by 4-6 and PL by 9. Best fruit flavour is attained when fruit are left to fully ripen on the tree before picking. At 0-1°C, AP will store for 1-2 weeks, PL for 2-4 and PN for up to 5.
All are eaten fresh, dried or canned and used in numerous processed forms.
They are attacked by many pests and diseases, with drier environments leading to lower disease load. Some problems that may need to be managed are Medfly, leaf curl, shothole and birds.
In our climate, stone fruit trees need considerable management but will produce bounteous crops.