Rick Dunst, Viticulturist, Double A Vineyards, Inc. Winter injury caused by low winter temperatures is an important limiting factor to grape production in many regions the United States. Hardiness is determined by using a number of sources, including university publications, variety release bulletins, and our own and other grower’s experiences. A hardiness zone is a geographically-defined area ...

The “polar vortex” of cold Arctic air that affected a large portion of the continental United States during early January 2014 was responsible for widespread transportation delays and a shutdown of activities at many schools and businesses. Blizzard conditions persisted for several days near Buffalo, New York, for the first time since 1993. Air temperatures around -10°F were common in western N...

There are many factors that influence whether or not a specific grape selection will survive and be capable of producing high quality fruit at a certain location, including winter hardiness, length of growing season, and risk of spring frost. A common measure of the growing season is Growing Degree Days (GDD). Grapevine development during the growing season is strongly influenced by air tempera...

Rick Dunst, Viticulturist, Double A Vineyards, Inc. Selecting the proper rootstock for your vineyard is just as important as variety selection. Rootstocks are used to induce or reduce scion vigor or to overcome specific soil limitations caused by physical factors such as soil pH and high salt content, or biological factors such as phylloxera, nematodes, and cotton root rot. While some cultivars...

Once an appropriate variety and rootstock are chosen for a site, vineyard design becomes an important consideration that will affect the performance of the vineyard for its lifetime. Considerations include row orientation, vine spacing between rows and within the row, and trellis height. Row Orientation The optimum orientation of vineyard rows is north to south in order to maximize sunlight exp...

Rick Dunst, Viticulturist, Double A Vineyards, Inc.    Grapevine red blotch-associated virus (GRBaV) is a recently identified virus which represents the latest addition to the long list of graft-transmissible agents that have been discovered in grapevines. This article will summarize what is currently known and not known about red blotch, and the future for the production of virus-free “cleaner...

Rick Dunst, Viticulturist, Double A Vineyards, Inc. After nearly twelve months of taking care of your vineyards, the last decision you make can be the most agonizing and difficult– when is it time to harvest the fruit?  As grapes mature, they develop aromas and flavors, and the chemical composition of the fruit changes.  Knowing when those factors have reached optimum levels is both an art and ...

Rick Dunst, Viticulturist, Double A Vineyards, Inc. Higher than average precipitation across many parts of the Eastern and Midwestern states has brought disease management issues to the forefront. Over the past several weeks, our staff has been contacted by grape growers from many growing regions with disease problems in their vineyards, many which had not been seen in prior years, or at least ...

Rick Dunst, Viticulturist, Double A Vineyards, Inc.  It is the time of year when our office starts receiving calls about “bumps” forming on grape leaves. While pest identification is usually quite difficult when based solely on a rough description of the symptoms, “bumps” on grapevine leaves are almost always associated with the aerial, or leaf form, of phylloxera. Phylloxera (Daktulosphaira vi...