Wine Grape Growing

Glossary

G

GALL. An abnormal growth of plant tissue caused by stimuli external to the plant itself. They are generally caused by insects (as in Phylloxera leaf galls), bacteria (as in Crown gall) or parasitic fungi.

GDD (Growing Degree Days). Sum of the mean monthly temperature above 50 degrees F (10°C) for the period concerned (in grapes, from April 1 to October 31), expressed as degree-days.

GEOGRAPHIC INFORMATION SYSTEM (GIS). A computer-based system used to input, store, retrieve, and analyze geographic data sets. The GIS is usually composed of map-like spatial representations called layers which contain information on a number of attributes such as elevation, land ownership and use, crop yield and soil nutrient levels.

GIRDLING. The removal of a ring of bark (down to the phloem, not including the cambium) from a shoot, cane or trunk. Often done in table grape production to increase berry size.

GLOBAL POSITIONING SYSTEM (GPS). A system using satellite signals (radio-waves) to locate and track the position of a receiver/antenna on the Earth. GPS is a technology that originated in the U.S. It is currently maintained by the U.S. government and available to users worldwide free of charge. There are 30 satellites in the GPS constellation.

GRAFT. The union between the scion of and a resistant rootstock of another species.

GRAFT UNION. The point where rootstock and scion variety are joined.

GRAFTING. In a viticultural context, usually grafting a European fruiting vine (or scion) on to a native or American-hybrid rootstock.

GROW TUBE (a.k.a. VINE SHELTER). A hollow, cylindrically shaped, man-made tube (usually made of plastic) which is sometimes placed over vines in an effort to enhance the growth environment of young vines.

GUYOT SYSTEM. A training system popular in Europe, the vine is pruned to one fruiting cane that is secured to a fruit wire, and one renewal spur that will become the fruit cane for the next year.

GYPSUM REQUIREMENT. The approximate amount of gypsum needed per acre to lower the exchangeable sodium percentage of the soil to a desired level.