Wine Grape Growing
DEEP PERCOLATION. Movement of water downward through the soil profile below the root zone, which is lost to the plants and eventually ends up in the groundwater.
DEFOAMING AGENT. An adjuvant used for suppressing both surface foam and trapped air in the spray mixture.
DEGREE DAYS. A method of classifying the climate based on the number of days the temperature is within a range that vines can grow. In California, climates are rated from coolest (Region I) to the warmest (Region V). This classification can help winemakers determine where to plant which variety.
DESUCKERING. The removal of young, non-fruit-bearing shoots from a vine.
DEVIGORATION. Controlling vine vigor, either by using a devigorating rootstock, limiting irrigation, planting on shallower soils, or training the shoots downward.
DISTAL. The end of the stem towards the growing tip
DORMANCY. That stage when the plant is not actively growing. For grapevines it is usually characterized by average air temperatures below 50°F. Vines need a minimum of about 60 days of dormancy.
DORMANT BENCH-GRAFT. A grapevine consisting of a rootstock and a scion, grafted in the nursery and planted out in a nursery row for its first year of growth. It is then dug up when dormant and sold to the customer
DORMANT PRUNING. Annual removal of wood during the vine's dormancy.
DOUBLE PRUNING. One pruning cut in late winter or early spring followed by a second pruning cut after the threat of frost is past but before appreciable shoot growth has occurred. Practiced where spring frosts are common.
DOWNY MILDEW. A fungal disease of the vine.
DRIFT RETARDENT. An adjuvant used in spray mixtures to reduce drift.
DRONES. See Unmanned Aerial Vehicles (UAVs).