Horticulture Principles and Practices

12. Wildlife attraction. Trees in the landscape and other ornamentals attract birds into
the area. Fruiting plants attract birds more than nonfruiting types. Examples of
good wildlife-attracting trees are Crataegus phaenopyrum, which produces
bright-red fruits in fall, and American beech (Fagus grandifolia).
13. Diseases. Certain species have devastating disease problems, making their use
problematic. For example, the American elm (Ulmus americana) is susceptible to
Dutch elm disease. A tree that matures only to be attacked by diseases must be
removed from the landscape at high cost.
14. Allergies. Flowering trees that produce copious amounts of pollen may pose allergy
problems in affected homeowners.
17.11 PURCHASING TREES FOR PLANTING
Care must be taken to select very healthy plants for installing in the landscape. The
following are factors to consider in purchasing trees for use in the landscape.
17.11.1 TYPE OF SEEDLING
Nurseries raise tree seedlings for sale to homeowners and landscape contractors. In terms
of how they are grown and packaged for sale, there are three classes of tree seedlings—
bare-root trees, balled and burlapped trees, and container-grown trees.
Bare-Root Trees
As the name indicates, a bare-root tree seedling is dug up without a ball of soil around
the roots. Deciduous species with stem diameters of less than 1 inch may be transplanted
as bare-root seedlings. Seedlings are prepared in this way when the plants are dormant
(i.e., winter). Deciduous plants are usually sold as bare-root seedlings. Conifer seedlings
that are not more than three years old are also frequently sold this way. Bare-root plants
are inexpensive to raise and purchase. Seedlings tend to lose some of their roots when
uprooted, which places them in jeopardy of dying during transplantation. If it cannot be
planted immediately, the bare-root seedling should be heeled in (roots covered up in a
shallow trench).
Balled and Burlapped Trees
A tree seedling may be harvested for transplanting by digging a certain distance around
the trunk and lifting it with a ball of soil around the roots. The soil ball around the roots
is usually at least 12 inches for each 1 inch of trunk diameter. The soil is then tightly
wrapped in a burlap sack, thus the name balled and burlapped (B&B) seedling. Balling
and burlapping is an expensive operation, which increases the price of such seedlings.
Evergreen trees (narrowleaf and broadleaf) are marketed in this way. Balling and burlapping
can be done any time of year. Deciduous trees may sometimes be handled by this
method. Transporting balled and burlapped trees is difficult because of their bulk, but the
seedlings establish quickly. The operation is mechanized, especially when seedlings are
large. Large trees, as previously indicated, are not burlapped but carried in mechanical
spades to the site at which they are to be transplanted.
Container-Grown Trees
Tree seedlings may be raised in containers (e.g., plastic, concrete, or wooden) for sale.
Seedlings may be raised in this restricted soil environment for twelve months or more
depending on the species. An overgrown plant may experience pot-bounding (i.e., roots
grow over each other in circles). Another problem with container-grown plants is rapid
soil drying. Potted plants should be irrigated on a frequent schedule. An advantage of
container plants is that they can be readily relocated in the nursery in adverse weather,
17.11 Purchasing Trees for Planting 527