Q. What exactly is espalier? Is this something I could do in my garden?
AEspalier is a centuries-old technique for training plants to grow in a flat plane, often less than a foot deep. Plants usually are trained to grow along a network of wires or a trellis that is attached to a wall or fence. The plant's branches are trained and pruned into informal or formal patterns. Candelabra or lattice patterns are popular. A number of trees and shrubs can be espaliered, but this technique is most commonly used for fruit trees, especially apples and pears.
Espalier has several practical purposes. For one, espalier plants can be grown in much less space. Espaliered fruit trees still produce bountiful crops, but in a fraction of the space needed for a full-sized tree, and espaliers are easier to harvest. In addition, it's possible to create a protected microclimate for the plant. Espaliers -- fruit trees in particular -- are usually grown along south-facing walls or fences, where the sun's heat is concentrated and cold winds are blocked. This extra protection is especially valuable in cool-summer climates (think England), where fruit needs that extra heat to ripen properly.
Espalier also can be an artistic addition to your garden. It does, however, require a long-term commitment to regular pruning and training. For more detailed instructions on planning, pruning and training espalier, check out Web sites on espalier and books on pruning. Specialty nurseries sell container-grown plants that are already started as espaliers. You will have to continue the training once you plant it in your own garden.
You also can view espaliered apple trees in the Home Demonstration Gardens at the Minnesota Landscape Arboretum in Chaska.
Q I sprayed insecticidal soap on my apple tree right after petal fall to try to prevent insects. I noticed insect damage early when the apples were still very small. I continued to spray with insecticidal soap, but almost all of the apples that did develop were damaged by insects. What did I do wrong?
A Insecticidal soap is a low-toxicity pesticide that can be effective against small, soft-bodied insects such as aphids. Unfortunately, it is not effective against major insect pests that damage apples. The early damage you saw was probably from plum curculio, a hard-shelled weevil-like insect that is unlikely to be killed by insecticidal soap. Codling moths can also damage apples fairly early. Later damage was probably caused by apple maggots, the most common pest of apples.
Apple maggot damage can be prevented or reduced without pesticides. Place individual apples in tightly closed paper bags (or plastic bags with a drain hole poked in one corner) by July 1st. However, plum curculios and codling moths can do their damage when the apples are just developing and are so small they're difficult to bag, although it may be worth trying this method. As a compromise, you could spray with an approved pesticide such as methoxychlor to prevent early damage. Spraying at petal fall and again seven to 10 days later should provide good protection. Bag the apples later so you don't have to spray for apple maggot.
Nancy Rose is a horticulturist, writer and photographer. To ask her a gardening question, call 612-673-9073 and leave a message. She will answer questions in this column only.