water breaker - a type of nozzle for a hose which breaks the forceful stream of water into a “shower” which is less injurious to small plants and results in more even watering.
water edge plant - plants who are adapted to a wet but not submerged site. These are generally found on the edge of lakes, streams or swamps. They are often called bog plants.
water-soaked - describes a wet, dark, often translucent looking blotch on a leaf. It is caused by a break in the wall of several cells in the plant tissue. This may be caused by the plant taking in too much water causing the cells to burst or may be the result of freezing which makes the cells expand and burst.
water sprout - fast growing branches that shoot straight up from horizontal branches. Common on crabapple trees after a severe pruning the previous year.
wavy - describes the edge of certain leaves See undulated
weed - refers to any plant not growing where you want it to grow. More on Landscape Weeds. Weed Images.
weed-n-feed - this is a combination product that contains both fertilizer and herbicides in granular form for use on the lawn.

The most common form of herbicide in these products is 2,4-D which is effective against dandelions and other common broadleaf weeds but may not work so well on tough weeds such as creeping Charlie.

Also, care must be taken when spreading weed-n-feed that none of the granules get scattered into the vegetable garden. Tomatoes are especially susceptible to damage from 2,4-D.
 
wetting agent - a substance that makes water "wetter." It is often added to irrigation water or mixed in with growing media that contain high amounts of peat moss. If allowed to dry out thoroughly, peat becomes hydrophobic which means that it will not readily absorb water.
whip - a young un-branched tree.
whip and tongue grafting

- a grafting technique in which the scion and rootstock are locked together tighter than in ordinary grafting, often used in bench grafting.
white-backed - leaves that have a glaucous bloom on the underside. Hosta hypoleuca is an example.
whitefly - small, white, flying insects resembling tiny moths which extract sap from the bottom side of leaves of certain plants. Rhododendrons seem to be a favorite food for them. Also, they can run rampant in greenhouses at times.
whorl - the arrangements of three or more leaves, flowers or other plant organs that emanate around the stem from one node in a circular pattern.
whorled - arranged in a ring around a stem. The branches of pines, fir and spruces are generally arranged in whorls. Examples include Catalpa, Hydrangea paniculata, Buttonbush (Cephalanthus occidentalis).
wildflowers Images of Wildflowers.
 
wilt - water is needed in the plant tissue in order to maintain turgor pressure to keep the plant firm. When there is a lack of water supply, blocked vascular tissue caused by a wilt disease or excessive water loss through transpiration, the plant looses turgor pressure and begins to droop.
wilting point - stage in soil moisture depletion when a plant is unable to take additional moisture from the soil and, as a consequence, becomes wilted.

See field capacity.
winter annual - an annual plant that germinates from seed in the fall, overwinters as a low-growing plant (often a rosette), flowers in the early spring, produces seed, and then dies.
winter damage or kill - damage or death of plant tissue due to the contents of the cells freezing and bursting.
Witche's broom - disease symptom characterized by an abnormal, massed, brush-like development of many weak shoots arising at or close to the same point in a broom-like proliferation of woody stems originating from closely spread nodes.

Certain species of trees such as sycamores are prone to diseases that encourage the development of witche's brooms.
 
woody plant - plant with woody tissue such as a tree or shrub, as opposed to those with soft, herbaceous stems.
wound - the area expressed when the epidermis or bark of a plant is cut or damaged.
wound dressing - compounds touted as being able to help pruning wounds "heal" but are actually generally not effective or needed.

The only exceptions would be for wounds on peach trees to prevent borer insects from entering and on red oak that are pruned during the growing season to prevent contact with the bark beetle that could be carrying oak wilt.

wounding - making cuts in the basal end of a cutting to expose cambial tissue to stimulate rooting.  The cutting away of a piece of bark near the base of a cutting or layer to expose the wood tissue and stimulate faster rooting at that point. Rooting chemicals are often applied to the wounded parts.
wrapping - the practice of covering the trunk of a young tree with paper tape or burlap to prevent frost crack or sun scald.
 

 

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