Glossary D

D

DAMPING OFF
Decay of young seedlings at ground level following fungal attack. Often the result of soil borne diseases and over watering.

DEAD HEADING
The removal of old blossoms to encourage continued blooming or to improve the appearance of the plant. The removal of faded heads of flowers.

DECAY CYCLE
The changes that occur as plants grow, die, and break down in the soil.

DECIDUOUS
Plants that shed all their leaves annually, usually in the fall.

DECOMPOSE, DECOMPOSITION
Decay. Rot. The breaking down of organic materials into smaller particles until the original material is no longer recognizable.

DECOMPOSE / DECOMPOSITION
To break down into component parts or basic elements; decomposition of organic materials by bacteria is an essential life process because it makes essential nutrients available for use by plants and animals.

DEFORESTATION
Loss of forest, usually as the result of clearing for agricultural (especially for cattle grazing) or other land uses such as roads and buildings. Deforestation destroys what may be an important sink for excess CO2 in the atmosphere.

DEGREE DAYS
A measure of the demand for heating ("heating degree-days") or cooling heating ("cooling degree-days") in a geographical location, expressed as degree-days per year to a base temperature. One degree-day means that the temperature needed to be changed by an average of 24 degree-hours during the year.

DETRITIVORES
Macroorganisms that eat decaying matter. Includes ant, beetle, centipede, cricket, earthworm, earwig, enchytraeid worm, millipede, mite, scorpion, slug, snail, spider, springtail, termite, woodlice.

DEXTROSE
One of the two principal sugars found in honey; forms crystals during granulation. Also known as glucose.

DESICCATION
Dehydration or loss of water.

DECIDUOUS
These are plants that loose their leaves at the end of the growing season. Maple trees are a good example.

DECUMBENT
Trailing stems on the ground with lateral shoots upright

DEFOLIATE/DEFOLIATION
The loss of leaves such as premature summer leaf drop.

DIBBLE
A stick or tool that makes planting holes in the soil or media

DIEBACK
Death of shoot tips such as by winter cold or chemical damage

DIPLOID
Having two set of chromosomes - normal for most species.

DIRECT SEEDING
Germination of seed in their final spot as opposed to a nursery.

DISBUDDING
The processing of removing extra buds to promote larger flowers.

DIOCECIOUS
A plant which bears either male or female flowers. (Compare to Monoecious)

DISC
The flat central part of a compound flower. It is made up of short, tubular florets.

DISSECTED
Cut or lacerated into segments - said of fringed petals or leaves.

DISTILLED WATER
Pure water free from dissolved salts. Formerly made by distillation, now produced chemically by demineralisation.

DIVISION
A method of propagating plants by separating each one into two or more sections and then repotting.

DIVISION BOARD FEEDER
A wooden or plastic compartment which is hung in a bee hive like a frame and contains sugar syrup to feed bees.

DOLOMITIC LIMESTONE
Sometimes used when 'liming' soil that has an acid pH level that is too high. As it contains calcium and magnesium carbonate it should be used only with soils that are also deficient in magnesium as well.

DORMANT PERIOD (DORMANCY)
A state of suspended growth. A state of rest and reduced metabolic activity in which plant tissues remain alive but do not grow.

DOUBLE FLOWER
The Latin name for this is "flore pleno." It refers to flowers that have many petals present, such as roses.

DOUBLE POTTING
An American term for placing a potted plant in a larger pot with damp peat moss surrounding it. The peat is kept moist and provides a humid evaporative effect for the potted plant nestled between it.

DORMANT OIL
Oil sprayed on deciduous trees while they are dormant. Dormant oils are used to kill overwintering insects or insect eggs on plant bark.

DORSAL
Relating to the back or outer portion of a plant part.

DOUBLE DIGGING
Soil bed preparation done by 2 or more spading sessions.

DOUBLE NOSE
Said of Narcissus bulbs with two growing apices or 'noses'.

DOUBLE SCREEN
A wooden frame, 1/2 to 3/4 inch thick, with two layers of wire screen to separate two colonies within the same hive, one above the other. An entrance is cut on the upper side and placed to the rear of the hive for the upper colony.

DRAWN
Excessively tall and weak growth, caused by plants being grown in too little light or too closely together.

DRIP IRRIGATION
Watering plants by small droplets over a long period of time each day

DRIP LINE
The line that marks the outer edge to which a tree's (or other plant's) branches spread. The drip line usually signals a change in microclimate, where the area under the tree, which sees less precipitation, sunlight, and wind and may also be subject to competition from the tree's roots, meets an area that isn't sheltered by the tree.

DRAWN COMBS
Combs with cells built out by honey bees from a sheet of foundation.

DRIFTING OF BEES
The failure of bees to return to their own hive in an apiary containing many colonies. Young bees tend to drift more than older bees, and bees from small colonies tend to drift into larger colonies.

DRONE
The male honey bee.

DRONE COMB
Comb measuring about four cells per linear inch that is used for drone rearing and honey storage.

DRONE LAYER
An infertile or unmated laying queen.

DRUMMING
Pounding on the sides of a hive to make the bees ascend into another hive placed over it.

DWARF VARIETIES
Varieties bred togrow smaller than their parent plants. Dwarf plants may lose the ability of the parents to set fruit (Bailey's dwarf highbush cranberry, Viburnum trilobum 'Bailey's Compact'). They may not resemble miniatures of their parents (dwarf Alberta spruce, Picea glauca var. albertiana 'Conica').

DWINDLING
The rapid dying off of old bees in the spring; sometimes called spring dwindling or disappearing disease.

DYSENTRY
An abnormal condition of adult bees characterized by severe diarrhea and usually caused by starvation, low-quality food, moist surroundings, or nosema infection.