Glossary

A

Adventitious

Produced in an unusual position or time; can refer to any plant organ (bud, root, shoot).

B

Bare-root

Bare-root plants are offered for sale with the soil removed from around the roots. These dormant plants are dug from growing fields, trimmed and freed of soil, and then protected against drying out until planting.

Beneficials

These are the much favored insects, arachnids, nematodes, and other organisms that eat or parisitize harmful insects and mites. Many beneficials already exist in our gardens, others can be purchased from nurseries or mail-order houses.

Branch collar; callus roll

This is the swollen ridge of bark surrounding a tree branch where it meets the trunk or a bigger branch. When trees are pruned, the branch collar of the limb to be removed should be preserved.

BT (Bacillus Thuringienis)

A bacterial disease that kills caterpillars after being sprayed or dusted on plants. Preparations containing BT can be found under several trade names such as Attack, Dipel, and Thuricide.

Bud

Little swollen areas along a stem, branch, or trunk where new growth may occur. Cutting above one of those buds stimulates growth.

Bud union; graft union

A swollen area just above the soil level where one variety has been grafted onto the rootstock of another variety. The bud union is not always swollen, and on some older plants it can be difficult to find. On young bare-root trees the bud union may look like a slight bend.

C

Cambium

A thin formative layer between the xylem and phloem of most vascular plants that gives rise to new cells and is responsible for secondary growth.

Cane

The woody stem of a rose or a berry plant, it can also be the jointed and often hollow or pith-filled stem of a bamboo or sugar cane.

Chance seedling

A term commonly used in reference to a cultivar's origin. It is a seedling arising by “chance” (from random, naturally occurring pollination), selected for desirable horticultural traits, and propagated vegetatively to maintain it as a cultivar or clone. “Delicious,” the most popular, economically important apple in America, first sprouted as a chance seedling in an Iowa orchard in 1872. “Starking” was the first of several sports produced from “Delicious.”

Chilling requirement

The number of hours of temperatures required below 45°, and refers most often to fruit trees that need a certain amount of cold weather in winter in order to bloom and bear fruit well the following year.

Clonal rootstocks

Clonal rootstocks are vegetatively propagated. Degree of size control and anchorage varies among dwarfing rootstocks. Choices outside of apple for size controlling rootstocks are more limited.

Clone

A clone is a genetically identical group of plants derived and maintained from one individual by vegetative propagation.

Cold hardiness (hardy)

The ability of plants to withstand cold injury (autumn-winter).

Cultivar

A cultivar is a contraction of the words “cultivated” and “variety.” It is a plant raised or selected in cultivation that retains distinct, uniform characteristics when propagated by appropriate methods.

Cutting

A section of a plant that is cut off and rooted to create a new plant.

D

Deciduous

Deciduous plants drop all their leaves once a year.

Dichogamous

Separate male and female trees.

Dormant

The term dormant describes the inactive or sleeping state in which a plant stops growing but is still alive.

Dormant spray

A solution of horticultural oil and water sprayed in winter on deciduous plants that have gone dormant and dropped their leaves. It kills overwintering pests and some fungi and is sometimes made with lime or sulfur.

Drip line

The rough circle that may be drawn on the ground around a tree where rain would drip off the outermost leaves is called the drip line. The most active roots are often located along this line.

Dwarfing rootstocks

These restrict growth and tree size for reasons such as slower nutrient uptake or smaller root systems. As a rule, these are asexually propagated, but can occur from seed (trifoliate orange).

F

Fireblight

A bacterial disease that causes the branches and fruit on apple trees, evergreen pear, pyracantha, and members of the rose family to turn black and die. An apt name, the plant looks as if it has been scorched.

Frost damage

Low temperature injury during some stage of the growing season. Parts affected are flower buds, flowers, and young fruit (spring) or near mature fruit or other tissues (fall).

G

Genetic dwarf

Genetic dwarfs are trees in which the internodes of the cultivar (scion) are greatly compressed. They are naturally small (five to eight feet) trees, even when grafted or budded onto standard, non-dwarfing rootstocks. Genetic dwarfs are best exemplified in peaches and nectarines. “Garden Delicious” is a genetic dwarf apple.

Grafting

A way to propagate a plant by inserting a section of one plant (the scion) into another plant (the stock).

H

Hardening

The process of achieving cold hardiness. In a broad sense, it’s the process that increases plants ability to survive the impact of unfavorable environmental stress. Water, nitrogen, other practices can affect this process.

Heading back

A type of pruning cut by which the end of a branch is removed to stimulate branching farther back on the branch or trunk.

Heel in

A means of preventing roots of Bare-root plants from drying out before they can be set out in the garden. Dig a shallow trench, lay the plant on its side so that roots are in the trench, then cover roots with soil, sawdust, or other material, moistened to keep roots damp.

Honeydew

A sticky substance secreted by aphids and several other sucking insects.

I

Insecticidal soaps

Biodegradble fatty acids (considered to be environmentally safe) that kill soft-bodied pests such as aphids by clogging their pores.

Integrated pest management (IPM)

An environmentally sensitive system of pest control in which beneficial insects are used and little or no chemical spraying is needed. When insecticides are used, they are targeted at a specific pest rather than a broad spectrum of insects which may also include beneficials.

M

Monoecious

Separate female and male flowers born on one plant.

P

Partially self-ferile

A heavier fruit crop is set when two or more varieties are planted nearby.

Pollination

The transfer of pollen from the male part of flowers (the anthers) to the female part (a stigma). The transfer is accomplished by insects.

R

Rootbound

When a plants roots become tangled, matted, and grow in circles. Always untangle rootbound plants when replanting them in a larger container or in the ground.

Rootstock

Sometimes called “stock,” this is the root system (plant) propagated from seed (seedling) or vegetatively as common in clonal rootstocks on which various cultivars are budded or grafted. Many rootstocks are used and possess traits that relate to anchorage, size control, tolerance of light and heavy soils, “wet feet,” specific nematodes and other plants and diseases.

S

Scion (pronounced SI-on)

A detached stem, usually dormant, used in asexual propagation by grafting techniques.

Seedling rootstocks

Seedling rootstocks are propagated from seed selected from various cultivars and typically produce well anchored trees. The terms standard or standard root or standard rootstock imply that the rootstock is seedling and that the cultivar grown on that rootstock will be a full size tree.

Self-fertile

One variety is needed for pollination.

Self-sterile

Two varieties are needed for pollination.

Sport

A sport is a mutation (genetic change), naturally occurring or induced to arise from a bud. It differs from the parent plant and can be vegetatively propagated to give rise to a new cultivar.

Spur

A spur is a short shoot with compressed internodes. They grow from two year or older branches and produce flowers and fruit. Flower spurs are best exemplified in apple and pear trees.

Spur type

Spur type is used in reference to the cultivar’s habit of growth; on a given amount of wood, spur type cultivars produce more fruiting spurs than do non-spur type cultivars. Spur type is used in reference to apple trees; spur types are natural or genetic semi-dwarfs, which are smaller, more compact, and about two-thirds the size of normal apple trees when grown on standard root.

Sucker

A cane that emerges from below the bud union, and therefore comes from the rootstock rather than from the variety grafted onto it. On other plants, a sucker is any unwanted, fast-growing, upright growth from roots, trunk, crown, or main branches.

V

Variety

Variety and “named variety” are commonly used to mean the same as cultivar. Technically, it means a naturally occurring variant of a species.

W

Winter burn

Associated with desiccation. Certain atmospheric conditions (wind) along with frozen ground and/or reduced soil moisture may not meet transpirational demands—a particular problem with evergreens.

Winter injury

Low temperature injury during rest (dormancy) and affects buds, stems, main limbs, and trunk.