Stone fruit are very susceptible to damage from the fungus and bacterial diseases that are prevalent in the cool humid climate conditions of the Puget Sound region. Also the lower seasonal heat levels, compared with regions such as eastern Washington or California, may not produce the high quality and flavor of the common commercial varieties. Some pollination problems occur when bad weather at bloom time limits bee activity, especially for early bloomers like apricots and early plums. Beginning in the early 1970s, Dr. Bob Norton started the stone fruit evaluation trials for the purpose of finding the stone fruit varieties that would produce a reliable crop of good quality fruit.
Productivity and disease susceptibility are the two major limiting factors in variety selection for peaches and nectarines in western Washington. Many varieties that do well in warmer areas are unproductive in the cooler marine climate of the Puget Sound region. Trials at Mount Vernon have eliminated a number of poorly performing varieties. Some reliable producers have fruit that is not top quality. Several introductions from the Harrow, Ontario fruit breeding program, and some other new introductions from New Jersey, Michigan, and Georgia have performed well.
Peach leaf curl, bacterial canker, brown rot and coryneum blight all attack peach and nectarine trees, so they are not good candidates for a no-spray orchard regime. Nectarines in particular can be subject to fruit cracking, which damages the fruit even if the cracks remain dry and do not develop rot.
For a summary of peach and nectarine variety trial results, see Stone Fruit Report 2009.
European, Asian and hybrid plums can all be grown successfully in our area. European plums (Prunus domestica) are generally the easiest to grow, and a wide range of these firm-fleshed, freestone types are available for home gardeners. Plum trees are usually vigorous and productive, less prone to disease and nutrition problems than other stone fruit kinds, and can be used not only for fresh eating but also for canning, drying, fruit leathers, and other culinary uses.
Japanese plums (P. salicina) and hybrid types (P. institia) can also do well, but variety selection is very important since certain varieties perform well and others are disappointing. Fruit is usually cling stone and more juicy than the European types. They are excellent for fresh eating and some can be used for flavorful jelly. Canning and drying are not recommended. Damson types and the small, round “bush” plums are often quite tart for fresh eating. However, they are very productive, supplying plenty of fruit for jelly, jam, and even wine.
For a summary of plum variety trial results, see Stone Fruit Report 2009.
Apricots are the most problematical of the stone fruits to grow in western Washington. They bloom early, often in February or March when cold weather prevents effective pollination or frost damages the flowers and young fruit. They are also susceptible to serious diseases such as bacterial canker, pseudomonas, and brown rot. Some varieties do not get as much heat as they need for proper maturity in our cool maritime climate. Here again research continues to seek out disease resistant, productive varieties that are better adapted to local conditions, but the goal of a truly well adapted apricot variety is still some way off. Shelter systems such as an espalier or trellis under the roof eaves, rain covers, high tunnels and hoop houses can help to give better results, combined with a vigilant disease control program.
For a summary of apricot variety trial results, see Harvest Report 2003: Tree Fruit.