Fruit-Tree Frenzy

With a little knowledge and care, growing fruit and nut trees can be a rewarding and delightful experience.

One of summer’s true pleasures is biting into a freshly picked fruit from your own tree. But backyard fruit and nut trees are not for everyone, and can be poor choices where yards or gardens are too small or too shaded, or if you are unable to provide the necessary care. Still, growing fruit of good quality is not difficult, and for those who enjoy gardening, the rewards can far exceed the small amount of effort it takes to learn about what problems to expect and how to manage them.

British Columbia gardeners are particularly fortunate in being able to grow a greater range of fruit and nut tree species than is possible in most other parts of Canada. The dry and sunny growing seasons and relatively mild winters typical of much of the Okanagan Valley allow cultivation of the widest variety of tree fruits and nuts. In more humid climates, the types of fruit trees that can be grown are limited mainly by diseases, whereas winter extremes and untimely frosts limit what can be grown in northern and eastern regions of the province, and at high elevations. However, with careful attention to microclimates and site selection, most of the temperate tree fruit species will survive in northern and eastern B.C., although they may fail to bear fruit in most years.

Nut trees

Walnuts, filberts (hazelnuts) and edible chestnuts (Castanea spp.) require little care and are easy to grow. They need considerable space, take seven to 10 years to come into bearing, and may require another tree close by for pollination. They are well suited to rural acreage, but are generally poor choices for suburban gardens, except in cases where the tree is intended to become a focal point of the garden landscape. Chestnuts and walnuts are beautiful and fast-growing trees that can reach about 15 metres in both height and canopy width within 20 years of planting.

Both English walnut and American black walnut produce good edible nuts. In coastal areas, a proportion of nuts may fail to produce kernels in years with cool summers, but in most years a mature tree will yield more than enough for both owners and squirrels. Not so with hazelnuts. Squirrels and Steller’s jays harvest hazelnuts well before they begin to fall, and leave few for the rest of us. Walnuts and hazelnuts, like most nuts, have high oil content and distinctive nut-like flavours. Roasted chestnuts have a unique sweet taste and texture completely unlike that of other nuts. These starchy nuts formed a significant part of the diet of First Nations peoples in eastern North America, and both the nuts and wood were prized by European settlers. While the American chestnut (Castanea dentata) was virtually eliminated in the early 20th century by a chestnut blight fungus from Asia, the less susceptible Chinese chestnut (Castanea mollissima) has thrived. In fact, all the chestnuts I have seen growing in B.C. have been of the Chinese variety.

Apples and pears

Apples and pears can be grown almost anywhere in B.C. In northern and eastern regions, primary consideration must be given to the cold hardiness of the scion cultivar and the rootstock. Dwarfing rootstocks for apples are suitable for use in coastal B.C. and southern interior valleys. In south coastal regions, look for resistance to apple scab when selecting cultivars, and avoid very susceptible ones, such as Red Delicious and Gala.

There are apples and pears suited to almost every taste and situation. Varietal differences in appearance, flavour, season, local adaptation and use are greater in apples and pears than in stone fruits, and hundreds of different cultivars are potentially available. Asian pears (often called apple pears) are distinct from European pears in both appearance and taste, and are said to be more disease resistant than European pears, although data to support this contention are lacking. There are no truly dwarfing rootstocks for pears, although many cultivars of both European and Asian pears will grow on quince rootstock and mature at about half the size of pear trees grown on “standard” rootstocks. Quince rootstock is sensitive to winter extremes, and trees on quince may have reduced longevity.

Stone fruits

Stone fruits are more difficult to grow in humid climates than are apples and pears, in part because of a disease called brown rot that loves rainy climates. Apricots and nectarines are highly susceptible to brown rot, and are not recommended in coastal B.C. Peaches are also highly susceptible, but some cultivars can be grown with success if espaliered against a south-facing wall under overhanging eaves that protect the tree from rain. Most cultivars of sweet cherry and some varieties of plum are too susceptible for culture in such coastal B.C. locations as Victoria, but others such as Ersinger, Pobeda and Italian plums, Montmorency and Meteor sour cherries, and Schneider’s Sildidge sweet cherry can be successfully grown if appropriate disease-management practices are followed. Other diseases that affect certain stone fruits are peach leaf curl and black knot on plums, while Cytospora and bacterial cankers affect all of the stone fruit species.

Know your fruit tree diseases

The list of diseases that can afflict fruit trees in coastal B.C. might seem enough to discourage anyone from trying to grow these trees. But by knowing what diseases to expect and by spending a little time learning about them, you can manage these problems and enjoy your trees as a source of delight and satisfaction.

Plant diseases are managed by integrating practices such as cultivar selection, site selection, fertilization, sanitation, pruning and other horticultural practices in ways that reduce the amount of fungus spores (inoculum) available for infection, and the ability of spores to infect. A little research into the nature of these diseases can pay off in crops of luscious fruits on beautiful trees.

The different species of pome fruits (apples and pears) are affected by the same or generally similar diseases and insect pests. Stone fruit species (plums, cherries, peaches, apricots, nectarines) are also affected by similar disease and insect pests, but these are distinct from those that affect pome fruits. Specific information about these diseases and pests is readily available in local libraries, or by searching the Internet.

Choice of variety is key

Selecting the right varieties is the first step to success. Cultivars differ widely in their susceptibility to various diseases. Some of the most popular and easy to grow in the southern interior are poor choices for coastal B.C. It may take some digging to find information about what cultivars do best in your situation, and where to obtain them. Local garden clubs, organizations such as the B.C. Fruit Testers Association (contact Barbara Chernick at 250-642-5825 or barbcher@islandnet.com), and events such as the UBC Apple Festival are good sources of such information.

Where to plant

Care in choosing where to plant fruit trees is important. Fruit trees require full sun and good drainage. Partial shade results in few blossoms, poor pollination and little fruit, while poor drainage equals root rot. As wet foliage favours disease, planting trees where there is good air circulation can reduce the length of time that leaves stay wet. Old, neglected fruit trees can be a source of inoculum for new trees, as can fallen leaves and diseased fruit, so new trees must be kept clear of these potential dangers. Be careful of over-fertilizing, which produces flushes of young, succulent tissues that are easily infected.

Pruning is important

Pruning is essential to fruit trees for many reasons; not only does it remove the diseased tissues that serve as sources of spores for new infections, but it also keeps the canopy open to the sunlight needed for blossom bud formation and fruit development, and for air movement that speeds drying after rains. However, pruning also creates wounds that can allow the entry of certain disease agents, and it can stimulate the growth of succulent new shoots that are easily infected.

Pruning is best done in late February or early March. The absence of leaves at this time of year allows you to see the tree framework and spot cankers, black knots (on plums) and other kinds of damaged wood that should be removed. Wound healing, which blocks the entry of fungi and bacteria that might otherwise enter through wounds, begins as soon as the sap starts to rise in the spring. Stone fruits in particular should be pruned as late as possible in the dormant season, to reduce the risk of infections that lead to Cytospora and bacterial cankers.

Both training and pruning are needed to get good yields of high-quality fruit each year. Training consists of bending selected shoots toward the horizontal, so that they develop into limbs that branch at wide angles from the trunk. Limb angles can be set by placing spreaders between the branch and the stem, by hanging weights on the branches or by tying them down to a desired angle when limbs are young and supple.

Very little pruning is needed during the first three to four years after a tree is planted. After that, practise yearly pruning to take out suckers and crowded branches, and to stimulate development of new shoots. Apples and pears form blossom buds mostly on shoots that are two to four years old. Pruning stimulates the growth of new shoots behind the point of each pruning cut, and thus can be used to maintain a supply of fruiting wood throughout the tree, rather than only on the outer fringes of the canopy. Mature trees that have not been pruned for several years, but which are otherwise sound, can be made highly productive by the selective removal of old and crowded branches. This should be done over a period of three to four years because if massive pruning is done all at once, a dense growth of suckers will result. Garden clubs often have members who can instruct in pruning, while the B.C. Fruit Testers Association holds an annual pruning party. There are also many excellent websites with detailed explanations and diagrams, such as: www.ces.ncsu.edu/depts/hort/hil/ag29.html#pruning

The following plants are hardy up to the zone number indicated:
• American black walnut (Juglans nigra) – zone 4 for most cultivars
• Chinese chestnut (Castanea mollissima) – zone 5
• English walnut (Juglans regia) – zone 6 for most cultivars
• filbert/hazelnut (Corylus avellana) – zone 5
• Italian or Spanish chestnut (Castanea sativa) – zone 5
• Hardiness of apples, pears, apricots, nectarines and peaches depends on the hardiness of the scion and the hardiness of the rootstock, both of which can vary a great deal. Please check with your supplier for recommendations for your part of the province.

Jim Rahe is a biologist and pest management specialist at Simon Fraser University. He and his wife Mary Ann own and operate Annie’s Orchard near Aldergrove.